Introduction

Migrants are individuals who enter a foreign country to live or work. From the perspective of the host country, immigrants are those individuals who have come from abroad. An estimated 244 million people worldwide have migrated out of their countries of origin, fleeing war or poverty or pursuing the dream of a better life. According to Brazilian Federal Police data, there are 117,745 foreigners living in the country; the majority are natives of Bolivia, Colombia, Argentina, China, Portugal, and Paraguay. Searching for employment, reuniting with family members, or seeking refuge for humanitarian reasons are the main motivations of migrants to Brazil. Mental health professionals, including psychologists, physicians, and nurses, will come into contact with adult and child migrants in a variety of settings, including schools, community centers, mental health facilities, and hospitals, and will need to know how to approach this population.

Migrants are often subjected to specific risk factors for mental health problems, mainly related to exposure of stressful and traumatizing experiences, including racial discrimination, urban violence, abuse by law enforcement officers, forced removal or separation from their families, detention or reclusion, and/or deportation. Stress and trauma have been robustly associated with risks for mental disorders, including but not limited to posttraumatic stress disorder (PTSD), major depressive disorder, psychosis, and suicide.

Stress is currently conceptually understood as a complex, multidimensional process by which some environmental factor (the stressor) triggers a physical and psychological response to which the individual must adapt. Adaptation is understood as a dynamic process by which the individual’s thoughts, feelings, behavior, and biophysiological mechanisms continually change to fit a changing environment. When the adaptation resources of the organism are overwhelmed, a mental disorder can prevail, with specific symptoms and associated behaviors, potentially including severe high-risk behaviors such as suicide. As it requires constant adaptation to a new environment, the migration process is generally assumed to be a major chronic environmental stressor.

Nevertheless, the impact of migration on mental health is still a relatively unexplored issue in Brazil. It is critical that the impact of stress and trauma on vulnerability to mental health problems, especially PTSD, be known in order to develop appropriate interventions for prevention, recognition, and provision of early, culturally appropriate care for migrant populations. The objective of this study was to critically review the literature on the link between migration and stress, emphasizing the stress-related disorder PSTD, and to discuss its implications for Brazilian mental health services.

Methods

The PubMed, SciELO, LILACS, and ISI Web of Science databases were searched for articles published in Portuguese, English, Spanish, or French, and indexed from inception to 2017. The following keywords were used: migration, mental health, mental health services, stress, posttraumatic stress disorder, and trauma. We included original studies, reviews, and meta-analyses. Furthermore, the reference lists of selected articles were handsearched for additional publications of interest.

Results

Stress and migration

Several authors agree that migration is associated with specific stressors, mainly related to the migratory experience and the necessary process of acculturation occurring in adaptation to the host country; these have potential consequences in various areas, including mental health. Many authors state that the migrant population is more vulnerable to health issues, especially psychological disorders, along with a higher level of anxiety or greater pessimism about the future, often caused and/or compounded by the loss of one’s social support network and isolation due to lack of knowledge.

One of the characteristics of migration-related stress is its chronicity. Some of the multiple stressors involved include feelings stemming from “not belonging to a single place,” weak social conditions (e.g., lack of documentation, exploitation at work, poor housing conditions), linguistic and cultural changes, loneliness, failure of one’s migration project, and the everyday struggle to survive. From a psychodynamic point of view, migration can be conceived as a process similar to mourning, in which the individual moves away from family and loved ones; from his language, culture, country, social status, and contact with the groups to which he belongs; and into possible insecurity. According to the Achotegui, the migration process involves three types of mourning: simple mourning, which takes place and is worked through in good conditions; complicated mourning, which involves serious difficulties in the working through of the migratory experience; and extreme mourning, which occurs in a problematic way and cannot be processed, overwhelming the adaptive capacities of the subject and leading to the so-called “immigrant syndrome with chronic or multiple stress” or “Ulysses syndrome.” Achotegui named the syndrome after the myth of Ulysses and the odyssey of his return to Ithaca after the end of the Trojan War. Ulysses syndrome was defined as a stress-related clinical picture which includes four sets of manifestations: 1) in the depressive set: sadness, crying, guilt (paranoid type) and ideas of death (although infrequent); 2) in the anxious set: tension and nervousness, excessive and recurrent worries, irritability, and insomnia; 3) in the somatization set: headache, fatigue, and musculoskeletal, abdominal, and thoracic somatizations; and 4) in the cognitive set: memory deficit, attention deficit, and physical and temporal disorientation.

Stress and acculturation

Acculturation is defined as a multidimensional process involving changes in many aspects of migrants’ lives, including language, cultural and ethnic identity, attitudes and values, customs and social relations, gender roles, eating patterns, artistic expressions, and communication. Acculturation can occur in stages, with migrants learning the new language first, followed by behavioral changes and participation in culture. From a cultural standpoint, while some settings (such as workplaces or schools) are associated predominantly with the host country, others (such as the home or neighborhood) may be associated predominantly with the culture of the country of origin. From this perspective, acculturation implies coexistence of both cultures, providing access to different types of resources, including those necessary for the promotion and restoration of mental health that would be expected to be linked to better mental health outcomes.

Psychological acculturation refers to the dynamic process that begins when immigrants enter their new country and begin to adapt to its culture. Behavioral acculturation refers to the degree to which immigrants participate in their culture of origin and/or in the new culture. In addition to adopting new habits, adult migrants can continue to participate in their culture of origin and establish friendships with fellow migrants from their home country, with whom they can share interests and values, consume ethnic food, and read printed material or electronic media in their native language.

According to Berry et al., the acculturation model includes four dimensions: integration, assimilation, separation, and marginalization.

1. Integration: the individual maintains aspects of their culture of origin, but also acquires traces of new current culture. This strategy can only be pursued in explicitly multicultural societies, based on values of acceptance of cultural diversity and with a low level of prejudice, that is, minimal levels of racism, ethnocentrism, and discrimination.

2. Assimilation: the individual does not wish to maintain their cultural identity of origin, and fully acquires the traits of the new culture. Value is ascribed to one’s relationship with the new reality.

3. Separation: the individual places value only on aspects of their original culture, refusing integration into the new country.

4. Marginalization: the individual does not maintain traces of his original culture, nor does he identify with the values of the new culture; he stays on the sidelines. This mode may be characterized by a high level of anxiety, a sense of alienation, and a loss of contact with the two groups. Berry justifies that formal education is a personal resource and a protective factor in itself against problems of adaptation, as it helps in problem-solving and decreases stress. Occupational status and support networks also promote good adaptation. On the other hand, great cultural distances between the original and new culture imply the need for extensive cultural relearning, which can cause uninterrupted conflict and lead to adaptive difficulties.

Problems caused by acculturation include changes in gender roles, intergenerational conflicts, family conflict and communication difficulties, reversal of roles in the family, negotiation of identity and loyalty to the culture of origin and to the new culture, solitude, and isolation. Conflicts between generations are common in migrant families, reflecting a gap between the acculturation of parents and children. Migrant children tend to adapt their behavior to the host culture rapidly. As immigrants, parents and children can live in worlds with different cultural contexts, which can be a source of parent-child arguments and conflicts about friendships, dating, marriage, gender roles, and career choices. Because immigrant parents are immersed mainly in one cultural context and their children in another, parents often know little of their children’s life away from home. For children of immigrants, it may be difficult to live with the expectations and demands of one culture at home and another at school. Children may not turn to their parents with problems and worries, believing that their parents do not know the host culture and its institutions well enough to provide good advice or help. In some cases, second-generation immigrant children and adolescents may undergo role reversal and translate their parents from their native language into the language of the new country or help parents and grandparents navigate the culture of the new country. Older adult migrants are often those most vulnerable to mental health problems, with the exception of victims of war and torture.

Acculturative conflicts are often the reason that brings immigrant families to psychological or psychiatric treatment. Even immigrants who have lived in a new country for a long time and seem to have adopted its lifestyle can continue to maintain a strong identification with their culture of origin. The structures of psychological and psychiatric care services should include programs designed to help immigrants adapt to the new context, value the need to learn the ways of the new culture, and maintain a connection with their old country and culture.

Traumatic events in migrants

The challenge in offering access to appropriate mental health services to migrants arises not only from cultural and linguistic barriers, but also from the impact of their exposure to traumatic events and stressors. Traumatic factors are usually associated with the experience of migration, but the literature indicates that they could occur in pre-migratory stages, during the migratory process, or even in the post-migratory period.

The impact of traumatic events on mental health seems to be influenced by their frequency, intensity, and duration. A meta-analysis conducted by Bogic et al. found that, regarding war-related factors, a higher number of traumatic experiences was the factor most robustly associated with the presence of mental disorders, including PTSD. In the same line, Nygaard et al. described a 40.9% prevalence of psychotic experiences migrants with refugee status and known PTSD; the most common experiences were auditory hallucinations (66.2%) and persecutory delusions (50%), which were more prevalent in individuals exposed to torture and imprisonment. Different influences, such as childhood abuse and traumatic events, interact in complex ways to determine risk of psychotic disorder. Migration is linked to a more severe psychosis, with a higher risk of “need for care,” and refugees are at higher risk of non-affective psychosis. Some authors state that the actual data suggest that the higher risk of schizophrenia in migrants is found in the least successful and most discriminated groups. This theory also encompasses that, to a certain degree, it is the reason why childhood trauma is also a risk factor. Other authors argue that, in studies on discrimination, the strongest effect was seen when there was discrimination including physical assault. This supports that exposure to hostility, threat, and violence are a cause of high psychosis risk, because they trigger more paranoia and delusions.

Interestingly, the meta-analysis conducted by Bogic et al. also indicated that post-migration socioeconomic level had no impact on PTSD risk, unlike the risk for major depression, in which socioeconomic disadvantage was a defined risk factor. Nevertheless, most studies indicate an independent effect of trauma severity (especially war trauma) on current mental health status, even after controlling for post-migration factors.

Posttraumatic stress disorder (PTSD) and migration

PTSD is a mental disorder with a severe and disabling clinical course, and it represents a considerable burden not only to patients and their families, but also for society and the health system. Exposure to traumatic events is a required factor for the development of the disorder; more precisely, PTSD is the only psychiatric disorder which requires occurrence of an external traumatic event prior to symptomatology for its diagnosis. Specific clinical manifestations, such as involuntary re-experiencing, hyperarousal, avoidance, and negative thoughts/feelings, occur for at least 4 weeks after the trauma. There are several well-known risk factors for PTSD onset, including factors related to trauma itself (severity, frequency), to the subject (genetics, physiological reactions, neuroanatomical abnormalities, resilience), and to peri- and posttraumatic components (socioeconomic level, social network, post-trauma difficulties).

A meta-analysis conducted by Lindert et al. revealed that, among 20 pooled studies published during 1990 and 2007 and focusing only on PTSD, the overall prevalence was 47% (95% confidence interval [95%CI] 31-63). The prevalence among refugees was almost twice as high as in labor migrants, putatively due to exposure to more risk factors, such as violence, war, and political persecution which are often stimuli for migration, as reported by Rasmussen et al. As mentioned, migrants often experience a set of traumatic experiences in their country of origin, during migration, and/or during the resettlement process in the new country; hence, it is not surprising that the prevalence of mental health problems, including PTSD, is high in this population. Nevertheless, this extremely high prevalence in migrants highlights the importance of careful attention to mental health in these populations, especially considering that the prevalence for PTSD among adults in the general population at any one time is up to 3%. Interestingly, the risk of PTSD in migrant populations decreases over generations, and reaches similar proportion at the third generation.

The risk factors for PTSD and the distribution of stressful and traumatic events differ considerably among countries that receive and send migrants, creating a complex relationship. Countries that receive migrants might pose heterogeneous obstacles, such as different culture/acculturation, weak network integration, difficulties in daily life, and poor access to the health system, while countries that send migrants might include backgrounds of political instability, low socioeconomic status, violence, and natural disasters. Several risk factors for PTSD have been reported in the literature, such as multiple traumatic events, being a victim of violence (e.g., torture, rape/sexual assault, armed conflicts), and economic hardship, but also factors involving post-migration difficulties, such as poor social network (e.g., loneliness and boredom, weak social integration), poor access to counseling services, socioeconomic/political instability (e.g., not having legal immigrant status, unemployment), detention, communication difficulties, acculturative stress associated with post-migration experiences, and others.

Communication skills are a topic that allows different understandings to be drawn from the same evidence. Frequently, these skills are reported as a concern by migrants, since better language performance allows access to better work, educational opportunities, and appropriate medical care. However, Chu et al. proposed an interesting view on this subject: better skills on the language from the receiving country were predictive of worse PTSD outcome, which could be related to higher expectations for coping with migration when compared to those with poor fluency. A similar finding was reported by Porter & Haslam. In this study, refugees with higher socioeconomic status prior to migration presented worse mental health outcomes due to a sharper drop in their status. Given all these risk factors and considering that they are irregularly distributed all over the world and over the years, it is important to consider each population in its historical context, and their personal experiences in both their previous and their current homes.

Limitations of the current data

Given these particularities, there are some limitations regarding research not only on migrants’ PTSD outcomes, but also on mental health from a much broader perspective. First, the interviews and evaluations in the included studies were frequently conducted in the language of the host country, which might lead to misinterpretations and jeopardize the sensitivity of the study. Language and cultural barriers can be overcome by using instruments for assessment in the migrant’s language, administered by someone from the same cultural background, as Norris & Aroian have done; this can provide more comfort to the subject. After this barrier is overcome, as stated above, the risk of mental health problems depends upon historical context and personal experiences; thus, it is important that the evidence found in the literature is not seen as static, but rather as something that requires periodical review and comprehensive assessment including biopsychosocial, spiritual, and subjective dimensions of experiences and mental illness. Lastly, besides the need for larger samples, it is important to note that sampling bias was inherent to most of the studies included; Song et al. proposed that poor mental health could be a factor hindering functioning in affected people, which, in turn, could prevent help-seeking behavior. Considering this and that most studies enroll voluntary participants, there is a possibility that results may have been underestimated. Additional limitations to be aware of include potential validation of transcultural assessment instruments and recall and self-selection bias.

Discussion

Considering the magnitude of the challenge to provide mental care for a huge number of international migrants, the literature regarding this subject is underexplored. Overall, the results of the available studies indicate that migration can be a stressful experience, and carries the potential to expose the individual to one or even a set of traumatic experiences, including complex trauma (such as sexual violence and war trauma). Some authors defend a selection hypothesis that posits that the increased rate of mental disorders in migrants is due to the selective migration of predisposed people, but longitudinal data are now available to oppose that theory. Many authors have stated that, for millions of people, migration is becoming a process that carries intense levels of stress, which can overwhelm human adaptive capacity and trigger mental or physical problems, symptoms, or illnesses. Some authors have even proposed the existence of a distinctive suffering condition typical of the stress associated with immigration: “Ulysses syndrome” or the “immigrant syndrome of chronic and multiple stress,” which resembles an adjustment disorder with cultural aspects. In this sense, the migrant syndrome of chronic and multiple stress would belong more to the field of mental health than to psychopathology itself, since immigrants do not necessarily suffer from mental illness, but rather experience a series of symptoms caused by multiple stressors. If the situation linked to the stressful events is not resolved, there is a risk that mental illness may develop. Outlining and recognizing this framework of adaptation to the stress associated with migration points out multiple possibilities on a continuum of adjustment, which would range from complete adaptation (or reported emotional growth via the mourning of migratory experience) to the immigrant syndrome of chronic and multiple stress, and even further, to the development of mental illness (e.g., PTSD if there was trauma involved).

Hence, considering that migrant populations are more affected by PTSD (and by other psychiatric disorders, such as major depression), which has been implicated in worse functioning, it is essential for the health system and health providers to pay attention to the mental health of migrants in relation to trauma exposure. Characteristics of the receiving country also have an impact on migrants’ mental health. For example, migrants living in an area with a low ethnic density are at an increased risk of psychosis. In general, treatment adherence is lower in immigrants, which is an aspect to consider when offering services to this population. Heterogeneity across studies regarding the population, the instruments used to assess exposure to traumatic experiences and mental health outcomes, and the convenience sampling method used are limitations which should be borne in mind when interpreting our findings. Many mental health studies, for example on suicide, often exclude people who recently immigrated (which is partly relevant considering that a culture-specific adjustment syndrome should not be treated as a mental disorder), but more specific research on migration and mental health is still warranted. Clinically significant dimensions of stress-related disorders, such as cognitive deficits, also remain highly underexplored among migrants. Nevertheless, the considerably higher prevalence of PTSD among migrants, and especially among refugees, does leave little room for doubt that those experiences are strongly associated with this specific illness.

Berry’s acculturation model proposes that, the more marginalized migrants are in their new community, the higher the risk to their mental health. In general, difficulties with social adjustment are often cited as a predictor of mental illness, drug relapse, and low adherence to treatment in various mental disorders.

Mental health services working with migrants in Brazil need to be prepared for a population with specific difficulties linked to the stress of acculturation and possible trauma, as well as to a profile of lower treatment adherence and more mental health illness in general. Clinicians must also have the cultural awareness and sensitivity needed to distinguish between genuine mental illness (such as PTSD) and psychosocial adjustment difficulties (such as Ulysses syndrome), and thus provide appropriate treatment.

Introduction

People who move to a foreign country to live or work are called migrants. From the perspective of the country they move to, they are called immigrants. Around the world, an estimated 244 million people have left their home countries. Many flee war or poverty, while others hope for a better life. In Brazil, federal data shows 117,745 foreign residents. Most come from Bolivia, Colombia, Argentina, China, Portugal, and Paraguay. The main reasons migrants come to Brazil are to find jobs, reunite with family, or seek safety for humanitarian reasons. Mental health professionals, including psychologists, doctors, and nurses, will encounter adult and child migrants in many places, such as schools, community centers, mental health clinics, and hospitals. These professionals need to know how to support this group.

Migrants often face specific risks for mental health problems. These risks are mainly due to stressful and traumatic experiences. Examples include racial discrimination, city violence, abuse by police, forced separation from families, detention, or deportation. Stress and trauma are strongly linked to the risk of mental disorders. These can include post-traumatic stress disorder (PTSD), severe depression, psychosis, and suicide.

Stress is understood as a complex process. An environmental factor, called a stressor, causes a physical and psychological reaction. The individual must then adapt to this reaction. Adaptation is a dynamic process where thoughts, feelings, behaviors, and body responses constantly change to fit a changing environment. If a person’s ability to adapt is overwhelmed, a mental disorder can develop. This can lead to specific symptoms and behaviors, potentially including dangerous actions like suicide. The process of migration usually requires constant adaptation to a new environment, making it a major ongoing stressor.

Despite this, the impact of migration on mental health is not well understood in Brazil. It is crucial to understand how stress and trauma increase the risk of mental health problems, especially PTSD. This knowledge is needed to create effective ways to prevent issues, identify them early, and provide culturally appropriate care for migrant populations. This study aimed to review existing research on the connection between migration and stress, focusing on PTSD. It also discusses what this means for mental health services in Brazil.

Methods

Articles published in Portuguese, English, Spanish, or French up to 2017 were searched in the PubMed, SciELO, LILACS, and ISI Web of Science databases. The search terms included: migration, mental health, mental health services, stress, posttraumatic stress disorder, and trauma. The search included original studies, reviews, and meta-analyses. Additionally, the reference lists of selected articles were checked for other relevant publications.

Results

Stress and Migration

Many experts agree that migration is linked to specific stressors. These are mainly related to the migration experience itself and the process of adapting to a new culture in the host country. These stressors can affect various aspects of life, including mental health. Many experts believe that migrants are more likely to experience health issues, especially psychological disorders. They may also have higher anxiety or more negative views about the future. This is often caused or worsened by losing their social support networks and feeling isolated due to a lack of understanding.

One key feature of migration-related stress is that it is ongoing. Some of the many stressors include feeling like they do not belong anywhere, poor social conditions (such as lack of documents, unfair labor, or bad housing), language and cultural changes, loneliness, failure of their migration plans, and the daily struggle to survive. From a psychological perspective, migration can be seen as similar to grieving. Individuals move away from family, friends, language, culture, country, social status, and their social groups. This can lead to feelings of insecurity. According to Achotegui, the migration process involves three types of grieving: simple grieving, which is handled well; complicated grieving, which involves serious difficulties in processing the migration experience; and extreme grieving, which is very problematic and cannot be processed. This overwhelms the person’s ability to adapt and leads to what is called "immigrant syndrome with chronic or multiple stress" or "Ulysses syndrome." Achotegui named this syndrome after the myth of Ulysses and his difficult journey home after the Trojan War. Ulysses syndrome is defined as a stress-related condition with four main types of symptoms: 1) depressive symptoms: sadness, crying, guilt, and thoughts of death (though rare); 2) anxious symptoms: tension, nervousness, excessive worry, irritability, and insomnia; 3) physical symptoms: headache, fatigue, and pain in muscles, abdomen, and chest; and 4) cognitive symptoms: memory problems, attention problems, and confusion about time and place.

Stress and Acculturation

Acculturation is a complex process where migrants change many aspects of their lives. These include language, cultural and ethnic identity, attitudes, values, customs, social relationships, gender roles, eating habits, artistic expression, and communication. Acculturation can happen in stages. Migrants might first learn the new language, then change their behaviors and join the new culture. Culturally, some places like workplaces or schools are mostly linked to the host country. Other places, like home or the neighborhood, might still be linked to the country of origin. From this view, acculturation means living with both cultures. This provides access to different kinds of support, including those needed for mental health, which would likely lead to better mental health.

Psychological acculturation describes the ongoing process that starts when immigrants arrive in a new country and begin to adapt to its culture. Behavioral acculturation refers to how much immigrants participate in their original culture or the new culture. Besides adopting new habits, adult migrants can continue to participate in their original culture and make friends with other migrants from their home country. They can share interests and values, eat ethnic food, and read materials in their native language.

Berry and colleagues describe four ways people adapt to a new culture: integration, assimilation, separation, and marginalization.

1. Integration: The person keeps parts of their original culture but also adopts aspects of the new culture. This is possible in multicultural societies that accept cultural diversity and have low levels of prejudice, racism, and discrimination.

2. Assimilation: The person does not want to keep their original cultural identity and fully adopts the new culture. They value their connection to the new reality.

3. Separation: The person only values their original culture and refuses to join the new country's culture.

4. Marginalization: The person does not keep ties to their original culture and does not identify with the new culture. They remain outside both. This can involve high anxiety, a feeling of being disconnected, and losing touch with both groups. Berry suggests that formal education helps people adapt by improving problem-solving skills and reducing stress. Job status and social support networks also promote good adaptation. On the other hand, large cultural differences between the original and new cultures mean a lot of new learning is needed. This can cause ongoing conflict and lead to difficulties in adapting.

Problems caused by acculturation include changes in gender roles, conflicts between generations, family conflicts, communication problems, role reversals in the family, struggles with identity and loyalty to both cultures, loneliness, and isolation. Conflicts between generations are common in migrant families because parents and children adapt to the new culture at different rates. Migrant children often quickly adapt their behavior to the host culture. Immigrant parents and children may live in different cultural worlds, leading to arguments about friendships, dating, marriage, gender roles, and career choices. Because immigrant parents are often more immersed in one cultural context and their children in another, parents may know little about their children's lives outside the home. For children of immigrants, it can be hard to meet the expectations of one culture at home and another at school. Children may not tell their parents about problems, believing their parents do not know the host culture well enough to offer good advice or help. In some cases, second-generation immigrant children and teenagers may take on parent-like roles. They might translate for their parents or help them navigate the new country's culture. Older adult migrants are often the most vulnerable to mental health problems, except for victims of war and torture.

Acculturation conflicts are often why immigrant families seek psychological or psychiatric help. Even immigrants who have lived in a new country for a long time and seem to have adopted its lifestyle can still strongly identify with their original culture. Mental health services should offer programs that help immigrants adapt to the new environment, recognize the importance of learning the new culture, and maintain a connection to their home country and culture.

Traumatic Events in Migrants

Providing suitable mental health services to migrants is challenging. This is not only due to cultural and language barriers, but also because of their exposure to traumatic events and stressors. Traumatic factors are typically linked to the migration experience, but research shows they can happen before migration, during the journey, or even after settling in the new country.

The impact of traumatic events on mental health seems to depend on how often they occur, how intense they are, and how long they last. A review by Bogic and others found that for war-related factors, experiencing more traumatic events was the strongest predictor of mental disorders, including PTSD. Similarly, Nygaard and colleagues reported that 40.9% of refugee migrants with known PTSD had psychotic experiences. The most common experiences were hearing voices (66.2%) and believing others were trying to harm them (50%). These were more common in individuals who had experienced torture and imprisonment. Different influences, such as childhood abuse and traumatic events, interact in complex ways to determine the risk of psychotic disorders. Migration is linked to more severe psychosis, with a higher need for care, and refugees have a higher risk of non-affective psychosis. Some experts suggest that the higher risk of schizophrenia in migrants is found in those who are least successful and most discriminated against. This idea also partly explains why childhood trauma is a risk factor. Other researchers argue that in studies on discrimination, the strongest effect was seen when discrimination included physical assault. This supports the idea that exposure to hostility, threats, and violence causes a high risk of psychosis by triggering more paranoia and delusions.

Interestingly, the review by Bogic and others also indicated that socioeconomic status after migration did not affect PTSD risk. However, it was a clear risk factor for major depression. Nevertheless, most studies show that the severity of trauma (especially war trauma) independently affects current mental health, even after accounting for factors after migration.

Post-Traumatic Stress Disorder (PTSD) and Migration

PTSD is a severe and debilitating mental disorder that creates a significant burden for individuals, families, and the healthcare system. Exposure to traumatic events is necessary for the disorder to develop; specifically, PTSD is the only psychiatric disorder that requires an external traumatic event before symptoms appear for diagnosis. Distinct symptoms, such as unwanted re-experiencing, heightened alertness, avoidance, and negative thoughts/feelings, must occur for at least four weeks after the trauma. Several known risk factors contribute to PTSD onset. These include factors related to the trauma itself (severity, frequency), individual factors (genetics, physiological reactions, brain abnormalities, resilience), and factors before and after the trauma (socioeconomic status, social support, difficulties after trauma).

A review by Lindert and others examined 20 studies on PTSD published between 1990 and 2007. The overall prevalence found was 47%. The prevalence among refugees was almost twice as high as among labor migrants. This is likely due to refugees’ exposure to more risk factors, such as violence, war, and political persecution, which often drive migration, as reported by Rasmussen and colleagues. As mentioned, migrants often experience a range of traumatic events in their home country, during migration, or during the resettlement process in the new country. Therefore, it is not surprising that mental health problems, including PTSD, are common in this population. This extremely high prevalence in migrants highlights the importance of carefully addressing their mental health. This is especially true when considering that the prevalence of PTSD among adults in the general population at any given time is up to 3%. Interestingly, the risk of PTSD in migrant populations decreases over generations, reaching similar levels by the third generation.

The risk factors for PTSD and the types of stressful and traumatic events vary significantly between countries that receive and send migrants, creating a complex relationship. Countries that receive migrants may present various challenges, such as different cultures, difficulties in integrating socially, daily life struggles, and poor access to healthcare. Countries that send migrants may have histories of political instability, low socioeconomic status, violence, and natural disasters. Several risk factors for PTSD have been reported, including multiple traumatic events, being a victim of violence (e.g., torture, rape/sexual assault, armed conflicts), and financial hardship. Post-migration difficulties also play a role, such as poor social support (e.g., loneliness, boredom, weak social integration), limited access to counseling, socioeconomic/political instability (e.g., lacking legal immigration status, unemployment), detention, communication difficulties, and acculturative stress related to post-migration experiences.

Communication skills can be understood in different ways. Migrants often report that language ability is a concern because better language skills can lead to better jobs, education, and proper medical care. However, Chu and colleagues proposed an interesting perspective: better skills in the receiving country's language predicted worse PTSD outcomes. This could be related to higher expectations for coping with migration compared to those with limited fluency. Porter and Haslam reported a similar finding. In their study, refugees with higher socioeconomic status before migration had worse mental health outcomes due to a sharper drop in their status. Given all these risk factors, and considering that they are unevenly distributed globally and over time, it is important to consider each population in its unique historical context and their personal experiences in both their former and current homes.

Limitations of Current Data

Given these specific issues, there are some limits to research on migrants' PTSD outcomes and mental health more broadly. First, interviews and evaluations in studies were often conducted in the host country's language. This can lead to misunderstandings and reduce the study's accuracy. Language and cultural barriers can be overcome by using assessment tools in the migrant's native language, given by someone from the same cultural background, as Norris and Aroian did. This can make the person feel more comfortable. Once this barrier is overcome, as mentioned above, the risk of mental health problems depends on historical context and personal experiences. Therefore, research findings should not be seen as fixed. Instead, they require regular review and a full assessment that includes biological, psychological, social, spiritual, and personal aspects of experiences and mental illness. Lastly, in addition to needing larger groups of participants, it is important to note that most studies had a sampling bias. Song and colleagues suggested that poor mental health could hinder a person's ability to function, which in turn might prevent them from seeking help. Considering this, and that most studies involve volunteers, the results might have underestimated the true extent of the problem. Other limitations to be aware of include the potential need to validate assessment tools across cultures, and biases related to memory and self-selection.

Discussion

Considering the immense challenge of providing mental healthcare to a large number of international migrants, the research on this topic is not extensive enough. Overall, available studies suggest that migration can be a stressful experience. It can expose individuals to one or multiple traumatic experiences, including complex trauma such as sexual violence and war trauma. Some researchers argue for a selection hypothesis, suggesting that the higher rate of mental disorders in migrants is due to predisposed individuals selectively migrating. However, recent longitudinal data challenge this theory. Many experts state that for millions of people, migration is becoming a process with intense stress levels. This stress can overwhelm human adaptive capacity and trigger mental or physical problems, symptoms, or illnesses. Some authors have even proposed a distinct condition of suffering specific to migration-related stress: "Ulysses syndrome" or the "immigrant syndrome of chronic and multiple stress." This resembles an adjustment disorder with cultural aspects. In this sense, the migrant syndrome of chronic and multiple stress would fall more within the realm of mental health than mental illness itself, as immigrants do not necessarily have a mental illness but rather experience symptoms caused by multiple stressors. If the stressful situation is not resolved, there is a risk of developing mental illness. Recognizing this framework of adaptation to migration-related stress highlights many possibilities along a continuum of adjustment. This ranges from full adaptation (or reported emotional growth through processing the migration experience) to the immigrant syndrome of chronic and multiple stress, and even further, to the development of mental illness (e.g., PTSD if trauma was involved).

Therefore, considering that migrant populations are more affected by PTSD (and other psychiatric disorders, such as major depression), which has been linked to poorer functioning, it is essential for healthcare systems and providers to focus on the mental health of migrants in relation to trauma exposure. Characteristics of the receiving country also influence migrants' mental health. For example, migrants living in areas with few people from their own ethnic group face a higher risk of psychosis. Generally, immigrants show lower adherence to treatment, which is an important factor to consider when offering services to this population. Differences across studies in terms of the population studied, the tools used to assess traumatic experiences and mental health outcomes, and the convenience sampling methods are limitations that should be kept in mind when interpreting these findings. Many mental health studies, such as those on suicide, often exclude recent immigrants (which is partly relevant as a culture-specific adjustment syndrome should not be treated as a mental disorder), but more specific research on migration and mental health is still needed. Clinically significant aspects of stress-related disorders, such as cognitive deficits, also remain largely unexplored among migrants. Nevertheless, the significantly higher prevalence of PTSD among migrants, especially refugees, leaves little doubt that these experiences are strongly linked to this specific illness.

Berry's acculturation model suggests that the more marginalized migrants are in their new community, the higher their risk for mental health problems. Generally, difficulties with social adjustment are often cited as a predictor of mental illness, drug relapse, and poor treatment adherence in various mental disorders.

Mental health services working with migrants in Brazil need to be prepared for a population facing unique challenges related to acculturation stress and potential trauma. They should also expect a tendency for lower treatment adherence and a higher overall incidence of mental health issues. Clinicians must possess cultural awareness and sensitivity to differentiate between genuine mental illnesses (like PTSD) and psychosocial adjustment difficulties (like Ulysses syndrome), enabling them to provide appropriate treatment.

Introduction

Individuals who move to a foreign country to live or work are referred to as migrants. From the perspective of the host country, these individuals are considered immigrants. Globally, an estimated 244 million people have migrated from their home countries due to conflict, poverty, or the desire for a better life. In Brazil, data from the Federal Police indicate that 117,745 foreign nationals reside in the country, primarily from Bolivia, Colombia, Argentina, China, Portugal, and Paraguay. The main reasons for migrants coming to Brazil include seeking employment, reuniting with family, or seeking refuge for humanitarian reasons. Mental health professionals, such as psychologists, doctors, and nurses, will encounter adult and child migrants in various settings, including schools, community centers, mental health facilities, and hospitals, and thus require knowledge on how to support this population.

Migrants frequently face unique risk factors for mental health problems. These factors are largely linked to stressful and traumatic experiences, which can include racial discrimination, urban violence, abuse by law enforcement, forced family separation, detention, or deportation. Stress and trauma are consistently associated with a higher risk for mental disorders, such as post-traumatic stress disorder (PTSD), major depressive disorder, psychosis, and suicidal thoughts.

Stress is understood as a complex process where an environmental factor, known as a stressor, triggers a physical and psychological reaction that requires adaptation from the individual. Adaptation involves continuous changes in an individual's thoughts, feelings, behaviors, and biological mechanisms to adjust to a changing environment. When the demands on an individual's adaptive resources become too great, a mental disorder can develop, leading to specific symptoms and behaviors, potentially including severe high-risk actions like suicide. The migration process generally involves constant adaptation to a new environment, suggesting it can be a significant and ongoing environmental stressor.

Despite this, the impact of migration on mental health remains a relatively under-researched topic in Brazil. Understanding how stress and trauma affect vulnerability to mental health problems, especially PTSD, is crucial for developing effective prevention strategies, early identification, and culturally sensitive care for migrant populations. The aim of this study was to review existing literature on the connection between migration and stress, with a specific focus on PTSD, and to consider its implications for mental health services in Brazil.

Methods

A literature search was conducted using the PubMed, SciELO, LILACS, and ISI Web of Science databases. The search included articles published in Portuguese, English, Spanish, or French, from the databases' inception up to 2017. Keywords used were: migration, mental health, mental health services, stress, post-traumatic stress disorder, and trauma. The search included original studies, reviews, and meta-analyses. Additionally, the reference lists of selected articles were manually reviewed for other relevant publications.

Results

Stress and migration

Many researchers agree that migration is linked to specific stressors. These stressors are primarily related to the migratory journey itself and the necessary process of acculturation, or adapting to the host country. These experiences can have various consequences, including effects on mental health. Several authors indicate that migrant populations are more susceptible to health issues, particularly psychological disorders, often accompanied by higher anxiety levels or increased pessimism about the future. Such challenges are frequently caused or worsened by the loss of social support networks and feelings of isolation due to unfamiliarity with the new environment.

One notable characteristic of migration-related stress is its chronic nature. The various stressors involved can include feelings of not belonging anywhere, challenging social conditions (e.g., lack of proper documents, workplace exploitation, poor housing), linguistic and cultural shifts, loneliness, the failure of one's migration goals, and the daily struggle for survival. From a psychodynamic perspective, migration can be viewed as a process akin to mourning. Individuals move away from family, loved ones, their language, culture, country, social standing, and established social groups, often into a state of uncertainty. Achotegui proposed that the migration process involves three types of mourning: simple mourning, which is processed under favorable conditions; complicated mourning, involving significant difficulties in processing the migratory experience; and extreme mourning, which is highly problematic and cannot be processed, overwhelming an individual's adaptive abilities and leading to what is called "immigrant syndrome with chronic or multiple stress" or "Ulysses syndrome." Achotegui named this syndrome after the myth of Ulysses' arduous return journey to Ithaca. Ulysses syndrome is defined as a clinical picture of stress with four groups of symptoms: 1) depressive symptoms: sadness, crying, paranoid guilt, and infrequent thoughts of death; 2) anxious symptoms: tension, nervousness, excessive and recurring worries, irritability, and insomnia; 3) somatic symptoms: headaches, fatigue, and musculoskeletal, abdominal, and chest pain; and 4) cognitive symptoms: memory deficits, attention deficits, and disorientation in time and space.

Stress and acculturation

Acculturation is defined as a complex process involving changes in many aspects of migrants' lives. These changes can include language, cultural and ethnic identity, attitudes and values, customs and social relationships, gender roles, eating habits, artistic expressions, and communication styles. Acculturation can occur in stages, with migrants often learning the new language first, followed by changes in behavior and participation in the new culture. From a cultural perspective, some environments, such as workplaces or schools, may primarily reflect the host country's culture, while others, like homes or neighborhoods, might predominantly reflect the culture of origin. In this view, acculturation involves the coexistence of both cultures, providing access to different resources, including those important for promoting and restoring mental health, which would likely lead to better mental health outcomes.

Psychological acculturation refers to the ongoing process that begins when immigrants arrive in their new country and start adapting to its culture. Behavioral acculturation describes the extent to which immigrants participate in their culture of origin or the new culture. In addition to adopting new habits, adult migrants can continue to engage with their culture of origin by forming friendships with fellow migrants from their home country, sharing interests and values, consuming ethnic foods, and reading materials in their native language.

According to Berry and colleagues, the acculturation model includes four main dimensions: integration, assimilation, separation, and marginalization.

1. Integration: Individuals maintain aspects of their original culture while also adopting traits of the new culture. This approach is most feasible in societies that explicitly value multiculturalism, accept cultural diversity, and have low levels of prejudice, racism, ethnocentrism, and discrimination.

2. Assimilation: Individuals choose not to maintain their original cultural identity and fully adopt the characteristics of the new culture, prioritizing their relationship with the new reality.

3. Separation: Individuals value only aspects of their original culture and resist integration into the new country.

4. Marginalization: Individuals neither maintain traits of their original culture nor identify with the values of the new culture, remaining disconnected from both. This state can be marked by high anxiety, a sense of alienation, and a loss of connection to both groups. Berry suggests that formal education acts as a personal resource and protective factor against adaptation problems by improving problem-solving skills and reducing stress. Occupational status and social support networks also contribute to good adaptation. Conversely, significant cultural differences between the original and new cultures necessitate extensive cultural relearning, which can lead to ongoing conflict and difficulties with adaptation.

Acculturation can lead to various problems, including shifts in gender roles, intergenerational conflicts, family communication difficulties, role reversals within the family, negotiating identity and loyalty to both cultures, solitude, and isolation. Conflicts between generations are common in migrant families, often reflecting differing rates of acculturation between parents and children. Migrant children tend to adapt quickly to the host culture's behaviors. As immigrants, parents and children may live in different cultural contexts, which can cause arguments and conflicts over friendships, dating, marriage, gender roles, and career choices. Because immigrant parents are often deeply embedded in one cultural context and their children in another, parents may know little about their children's lives outside the home. Children of immigrants may find it difficult to balance the expectations and demands of one culture at home with another at school. They might not seek parental advice for problems, believing their parents lack sufficient knowledge of the host culture and its systems. In some cases, second-generation immigrant children and adolescents may take on a role reversal, translating for their parents or helping them navigate the new country's culture. Older adult migrants, with the exception of war and torture victims, are often most vulnerable to mental health problems.

Acculturative conflicts are frequently the reason immigrant families seek psychological or psychiatric treatment. Even immigrants who have lived in a new country for an extended period and appear to have adopted its lifestyle may still strongly identify with their culture of origin. Mental health services should offer programs designed to help immigrants adapt to their new environment, appreciate the importance of learning the new culture's ways, and maintain connections to their original country and culture.

Traumatic events in migrants

Providing migrants with access to appropriate mental health services presents challenges, not only due to cultural and linguistic barriers but also because of the impact of their exposure to traumatic events and stressors. Traumatic factors are typically associated with the migration experience itself, but research indicates that these can occur before migration, during the migration process, or even after resettlement.

The impact of traumatic events on mental health appears to be influenced by their frequency, intensity, and duration. A meta-analysis by Bogic et al. found that, concerning war-related factors, a greater number of traumatic experiences was the most consistent factor linked to the presence of mental disorders, including PTSD. Similarly, Nygaard et al. reported a 40.9% prevalence of psychotic experiences among refugees with known PTSD. The most common experiences were auditory hallucinations (66.2%) and persecutory delusions (50%), which were more prevalent in individuals exposed to torture and imprisonment. Various influences, such as childhood abuse and traumatic events, interact in complex ways to determine the risk of psychotic disorder. Migration is associated with more severe psychosis, a higher need for care, and refugees face an increased risk of non-affective psychosis. Some researchers suggest that current data indicate a higher risk of schizophrenia among migrants who are least successful and experience the most discrimination. This theory also proposes that childhood trauma is a risk factor for similar reasons. Other authors argue that in studies on discrimination, the strongest effect was observed when discrimination included physical assault. This supports the idea that exposure to hostility, threats, and violence causes a high risk of psychosis by triggering increased paranoia and delusions.

Interestingly, the meta-analysis by Bogic et al. also indicated that post-migration socioeconomic status had no impact on PTSD risk, unlike the risk for major depression, where socioeconomic disadvantage was a clear risk factor. Nevertheless, most studies show an independent effect of trauma severity (especially war trauma) on current mental health status, even after accounting for post-migration factors.

Post-Traumatic Stress Disorder (PTSD) and migration

PTSD is a severe and debilitating mental disorder that creates a significant burden for patients, their families, society, and the healthcare system. Exposure to traumatic events is a necessary condition for the development of the disorder; specifically, PTSD is the only psychiatric disorder that requires a prior external traumatic event for diagnosis. Its specific clinical manifestations, such as involuntary re-experiencing, hyperarousal, avoidance, and negative thoughts/feelings, must persist for at least four weeks after the trauma. Various well-known risk factors contribute to PTSD onset, including factors related to the trauma itself (severity, frequency), the individual (genetics, physiological reactions, neuroanatomical abnormalities, resilience), and peri- and post-traumatic components (socioeconomic status, social support network, post-trauma difficulties).

A meta-analysis by Lindert et al., which pooled 20 studies published between 1990 and 2007 focusing solely on PTSD, revealed an overall prevalence of 47% (95% confidence interval [95%CI] 31-63). The prevalence among refugees was nearly twice as high as among labor migrants, likely due to increased exposure to risk factors such as violence, war, and political persecution, which often prompt migration, as reported by Rasmussen et al. As noted, migrants frequently encounter a range of traumatic experiences in their home country, during migration, or during resettlement in a new country. Therefore, it is not surprising that the prevalence of mental health problems, including PTSD, is high in this population. However, this exceptionally high prevalence among migrants underscores the critical need for careful attention to their mental health, especially considering that the prevalence of PTSD in the general adult population at any given time is up to 3%. Interestingly, the risk of PTSD in migrant populations decreases over generations, reaching similar proportions by the third generation.

The risk factors for PTSD and the distribution of stressful and traumatic events vary significantly between countries that receive and send migrants, creating a complex relationship. Receiving countries might present diverse obstacles, such as cultural differences/acculturation challenges, weak social integration, daily life difficulties, and poor access to healthcare. Conversely, sending countries might have backgrounds of political instability, low socioeconomic status, violence, and natural disasters. Various risk factors for PTSD have been documented, including multiple traumatic events, being a victim of violence (e.g., torture, rape/sexual assault, armed conflicts), and economic hardship. Additionally, post-migration difficulties such as poor social networks (e.g., loneliness, boredom, weak social integration), limited access to counseling services, socioeconomic/political instability (e.g., lack of legal immigrant status, unemployment), detention, communication challenges, and acculturative stress associated with post-migration experiences also contribute to the risk.

Communication skills are a topic that allows for different interpretations of the same evidence. Migrants frequently express concern about these skills, as better language proficiency enables access to better employment, educational opportunities, and appropriate medical care. However, Chu et al. proposed an interesting perspective: better skills in the receiving country's language predicted worse PTSD outcomes. This could be related to higher expectations for coping with migration among those with greater fluency compared to those with poor fluency. Porter & Haslam reported a similar finding: refugees with higher socioeconomic status before migration exhibited worse mental health outcomes due to a more significant decline in their status. Given all these risk factors and their uneven distribution across the globe and over time, it is important to consider each population within its historical context and their personal experiences in both their previous and current homes.

Limitations of the current data

Given these specificities, there are some limitations in research concerning not only PTSD outcomes in migrants but also mental health from a broader perspective. Firstly, interviews and evaluations in the included studies were often conducted in the host country's language, which could lead to misunderstandings and compromise the study's sensitivity. Language and cultural barriers can be overcome by using assessment instruments in the migrant’s native language, administered by someone from the same cultural background, as demonstrated by Norris & Aroian; this approach can provide greater comfort to the individual. Once this barrier is overcome, as noted, the risk of mental health problems depends on historical context and personal experiences. Therefore, it is crucial that the evidence found in the literature is not viewed as static but requires periodic review and comprehensive assessment that includes biopsychosocial, spiritual, and subjective dimensions of experiences and mental illness. Lastly, in addition to the need for larger sample sizes, it is important to acknowledge that sampling bias was inherent in most of the included studies. Song et al. suggested that poor mental health could hinder an individual’s functioning, which, in turn, might prevent them from seeking help. Considering this and that most studies involve voluntary participants, there is a possibility that the results may have been underestimated. Additional limitations to be aware of include potential issues with validating transcultural assessment instruments, as well as recall and self-selection bias.

Discussion

Considering the immense challenge of providing mental healthcare for a large number of international migrants, research on this topic remains underexplored. Overall, existing studies suggest that migration can be a stressful experience and has the potential to expose individuals to one or more traumatic experiences, including complex trauma such as sexual violence and war-related trauma. Some researchers support a selection hypothesis, which posits that the higher rate of mental disorders in migrants is due to the selective migration of individuals who are already predisposed. However, longitudinal data now challenge this theory. Many authors have stated that, for millions of people, migration is becoming a process associated with intense levels of stress, which can overwhelm human adaptive capacity and trigger mental or physical problems, symptoms, or illnesses. Some have even proposed a distinct suffering condition typical of immigration-related stress: "Ulysses syndrome" or the "immigrant syndrome of chronic and multiple stress," which resembles an adjustment disorder with cultural components. In this sense, the migrant syndrome of chronic and multiple stress might belong more to the field of mental health than psychopathology itself, as immigrants do not necessarily suffer from mental illness but rather experience a range of symptoms caused by multiple stressors. If the situation linked to these stressful events is not resolved, there is a risk that mental illness may develop. Recognizing this framework of adaptation to migration-related stress highlights multiple possibilities along a continuum of adjustment, ranging from complete adaptation (or reported emotional growth through processing the migratory experience) to the immigrant syndrome of chronic and multiple stress, and further, to the development of mental illness (e.g., PTSD if trauma was involved).

Therefore, considering that migrant populations are more affected by PTSD (and other psychiatric disorders, such as major depression), which has been linked to worse functioning, it is essential for the healthcare system and providers to prioritize the mental health of migrants in relation to trauma exposure. Characteristics of the receiving country also influence migrants' mental health. For instance, migrants living in areas with low ethnic density face an increased risk of psychosis. Generally, treatment adherence is lower among immigrants, which is an important consideration when offering services to this population. Heterogeneity across studies regarding population characteristics, instruments used to assess traumatic experiences and mental health outcomes, and the reliance on convenience sampling methods are limitations that should be kept in mind when interpreting findings. Many mental health studies, such as those on suicide, often exclude recent immigrants (which is partly relevant given that a culture-specific adjustment syndrome should not be treated as a mental disorder), but more specific research on migration and mental health is still needed. Clinically significant aspects of stress-related disorders, such as cognitive deficits, also remain largely unexplored among migrants. Nevertheless, the considerably higher prevalence of PTSD among migrants, especially refugees, leaves little doubt that these experiences are strongly associated with this specific illness.

Berry’s acculturation model suggests that the more marginalized migrants are in their new community, the higher their risk for mental health problems. Generally, difficulties with social adjustment are frequently cited as a predictor of mental illness, drug relapse, and low adherence to treatment in various mental disorders.

Mental health services in Brazil that work with migrants need to be prepared for a population facing specific difficulties related to acculturation stress and potential trauma. They also need to account for a profile characterized by lower treatment adherence and a generally higher incidence of mental health conditions. Clinicians must possess the cultural awareness and sensitivity necessary to differentiate between genuine mental illness (such as PTSD) and psychosocial adjustment difficulties (such as Ulysses syndrome), thereby ensuring appropriate treatment is provided.

Summary

Individuals who move to a foreign country to live or work are called migrants. The host country refers to these people as immigrants. About 244 million people worldwide have left their home countries due to war, poverty, or the desire for a better life. In Brazil, data from the Federal Police show that 117,745 foreigners reside there, mostly from Bolivia, Colombia, Argentina, China, Portugal, and Paraguay. Reasons for migrating to Brazil often include seeking employment, reuniting with family, or finding humanitarian refuge. Mental health professionals, including psychologists, doctors, and nurses, will encounter adult and child migrants in various places such as schools, community centers, mental health facilities, and hospitals. They need to understand how to work with this group.

Migrants frequently face specific risks for mental health issues. These risks often come from stressful and traumatic experiences like racial discrimination, urban violence, abuse by law enforcement, forced family separation, detention, or deportation. Stress and trauma are strongly linked to mental disorders such as post-traumatic stress disorder (PTSD), major depressive disorder, psychosis, and suicide.

Stress is understood as a complex process where an environmental factor (a stressor) causes a physical and psychological reaction that an individual must adapt to. Adaptation means that a person's thoughts, feelings, behaviors, and body mechanisms constantly change to fit a new environment. If a person's ability to adapt is overwhelmed, a mental disorder can develop, leading to specific symptoms and behaviors, including risky actions like suicide. Since migration requires constant adaptation to a new environment, it is generally seen as a major, ongoing environmental stressor.

However, the impact of migration on mental health remains a relatively unexplored topic in Brazil. Understanding how stress and trauma affect the risk of mental health problems, especially PTSD, is crucial. This knowledge is necessary for developing effective prevention strategies, early recognition, and culturally appropriate care for migrant populations. This study aimed to review existing research on the connection between migration and stress, focusing on PTSD, and to discuss what this means for Brazilian mental health services.

Methods

A search was performed on PubMed, SciELO, LILACS, and ISI Web of Science for articles published in Portuguese, English, Spanish, or French from the beginning of these databases until 2017. The keywords used were: migration, mental health, mental health services, stress, post-traumatic stress disorder, and trauma. The search included original studies, reviews, and meta-analyses. Additionally, the reference lists of selected articles were manually checked for other relevant publications.

Results

Stress and Migration

Experts generally agree that migration involves specific stressors, mainly related to the migratory experience and the necessary process of adapting to the host country. These can have consequences for various areas, including mental health. Many researchers state that migrants are more susceptible to health problems, especially psychological disorders, and often experience higher anxiety or pessimism about the future. This is frequently caused or made worse by the loss of their social support network and isolation due to a lack of understanding.

One key feature of migration-related stress is its ongoing nature. Various stressors include feelings of "not belonging," poor social conditions (such as lack of documentation, exploitation at work, or inadequate housing), language and cultural changes, loneliness, the failure of one's migration plans, and the daily struggle to survive. From a psychological perspective, migration can be seen as a process similar to grieving. Individuals move away from family, loved ones, language, culture, country, social status, and established social groups, often entering a state of uncertainty. According to Achotegui, the migration process involves three types of grief: simple grief, which is managed well; complicated grief, which involves serious difficulties in processing the migration experience; and extreme grief, which is problematic and cannot be processed. This extreme grief overwhelms a person's ability to adapt and leads to what is called "immigrant syndrome with chronic or multiple stress" or "Ulysses syndrome." Achotegui named the syndrome after the Greek myth of Ulysses and his difficult journey home after the Trojan War. Ulysses syndrome is defined as a stress-related condition with four types of symptoms: 1) depressive symptoms: sadness, crying, guilt (paranoid type), and infrequent thoughts of death; 2) anxious symptoms: tension, nervousness, excessive worry, irritability, and insomnia; 3) physical symptoms: headache, fatigue, and pain in muscles, abdomen, and chest; and 4) cognitive symptoms: memory and attention deficits, and confusion about time and place.

Stress and Acculturation

Acculturation is a complex process that involves changes in many parts of migrants' lives. These include language, cultural and ethnic identity, attitudes and values, customs and social relationships, gender roles, eating habits, artistic expression, and communication. Acculturation can happen in stages, with migrants often learning the new language first, followed by changes in behavior and participation in the new culture. From a cultural perspective, some environments (like workplaces or schools) are mainly associated with the host country, while others (like home or neighborhood) might be more linked to the culture of origin. In this view, acculturation involves the coexistence of both cultures, providing access to different resources, including those that help promote and restore mental health, which would likely lead to better mental health outcomes.

Psychological acculturation describes the ongoing process that begins when immigrants arrive in a new country and start adapting to its culture. Behavioral acculturation refers to how much immigrants participate in their culture of origin and/or the new culture. In addition to adopting new habits, adult migrants can continue to participate in their original culture and form friendships with fellow migrants from their home country. With these friends, they can share interests and values, eat traditional foods, and read materials or electronic media in their native language.

Berry and colleagues describe four main strategies for acculturation: integration, assimilation, separation, and marginalization.

1. Integration: Individuals keep parts of their original culture while also adopting aspects of the new culture. This strategy is only possible in societies that openly value multiculturalism, accept cultural diversity, and have low levels of prejudice, racism, ethnocentrism, and discrimination.

2. Assimilation: Individuals choose not to keep their original cultural identity and fully adopt the new culture. They prioritize their connection with the new reality.

3. Separation: Individuals value only their original culture and refuse to integrate into the new country.

4. Marginalization: Individuals neither maintain their original culture nor identify with the values of the new culture, staying disconnected from both. This can lead to high anxiety, a sense of alienation, and a loss of connection with both groups. Berry suggests that formal education acts as a personal resource and a protective factor against adaptation problems, as it helps with problem-solving and reduces stress. Job status and social support networks also promote good adaptation. Conversely, significant cultural differences between the original and new cultures mean a lot of cultural relearning is needed, which can cause ongoing conflict and lead to difficulties adapting.

Problems arising from acculturation include changes in gender roles, conflicts between generations, family conflicts, communication difficulties, role reversals within the family, negotiating identity and loyalty to both cultures, loneliness, and isolation. Intergenerational conflicts are common in migrant families because parents and children often acculturate at different rates. Migrant children tend to quickly adapt their behavior to the host culture. Parents and children, as immigrants, can live in different cultural contexts, which can cause arguments and conflicts over friendships, dating, marriage, gender roles, and career choices. Since immigrant parents are mainly immersed in one cultural context and their children in another, parents often know little about their children's lives outside the home. For children of immigrants, balancing the expectations of one culture at home and another at school can be challenging. Children may not share problems and worries with their parents, believing their parents do not know the host culture and its institutions well enough to offer good advice or help. In some cases, second-generation immigrant children and teenagers might take on adult roles, translating for their parents from their native language into the new country's language or helping parents and grandparents navigate the new culture. Older adult migrants are often most vulnerable to mental health problems, with the exception of war and torture victims.

Acculturation conflicts frequently lead immigrant families to seek psychological or psychiatric treatment. Even immigrants who have lived in a new country for a long time and seem to have adopted its lifestyle can still strongly identify with their culture of origin. Mental health care services should offer programs designed to help immigrants adapt to their new environment, appreciate the need to learn new cultural ways, and maintain a connection with their original country and culture.

Traumatic Events in Migrants

Providing appropriate mental health services to migrants is challenging due to cultural and linguistic barriers, as well as the impact of their exposure to traumatic events and stressors. Traumatic factors are usually linked to the migration experience, but research indicates they can happen before migration, during the migration process, or even after settling in a new place.

The impact of traumatic events on mental health seems to be affected by how often they occur, their intensity, and how long they last. A meta-analysis by Bogic and colleagues found that for war-related factors, a higher number of traumatic experiences was the strongest predictor of mental disorders, including PTSD. Similarly, Nygaard and colleagues reported that 40.9% of migrants with refugee status and known PTSD experienced psychotic symptoms. The most common symptoms were auditory hallucinations (66.2%) and persecutory delusions (50%), which were more common in individuals exposed to torture and imprisonment. Various influences, such as childhood abuse and traumatic events, interact in complex ways to determine the risk of psychotic disorder. Migration is linked to more severe psychosis and a higher need for care, with refugees facing a higher risk of non-affective psychosis. Some researchers suggest that current data indicate the higher risk of schizophrenia in migrants is found among those who are least successful and most discriminated against. This theory also partly explains why childhood trauma is a risk factor. Other researchers argue that in studies on discrimination, the strongest effect was seen when discrimination involved physical assault. This supports the idea that exposure to hostility, threats, and violence increases the risk of psychosis because it triggers more paranoia and delusions.

Interestingly, the meta-analysis by Bogic and colleagues also showed that post-migration socioeconomic status did not affect the risk of PTSD. However, it was a clear risk factor for major depression. Nevertheless, most studies indicate that the severity of trauma (especially war trauma) has an independent effect on current mental health, even after considering factors related to life after migration.

Posttraumatic Stress Disorder (PTSD) and Migration

PTSD is a severe and debilitating mental disorder that creates a significant burden for individuals, their families, society, and the healthcare system. Exposure to traumatic events is a necessary condition for developing the disorder; in fact, PTSD is the only psychiatric disorder that requires a specific external traumatic event to occur before symptoms appear for its diagnosis. Characteristic symptoms, such as involuntary re-experiencing the trauma, heightened arousal, avoidance, and negative thoughts/feelings, must last for at least four weeks after the trauma. Many well-known risk factors contribute to PTSD development. These include factors related to the trauma itself (severity, frequency), individual factors (genetics, physiological reactions, brain abnormalities, resilience), and factors experienced during or after the trauma (socioeconomic status, social support network, post-trauma difficulties).

A meta-analysis by Lindert and colleagues, which combined 20 studies on PTSD published between 1990 and 2007, found an overall prevalence of 47% (with a 95% confidence interval of 31-63%). The prevalence among refugees was almost twice as high as in labor migrants. This is likely due to refugees often being exposed to more risk factors such as violence, war, and political persecution, which frequently prompt migration, as reported by Rasmussen and colleagues. As mentioned, migrants often face a range of traumatic experiences in their home country, during migration, and/or during resettlement in a new country. Therefore, it is not surprising that mental health problems, including PTSD, are common in this population. This extremely high prevalence among migrants highlights the critical need for careful attention to their mental health, especially considering that the prevalence of PTSD in the general adult population at any given time is up to 3%. Interestingly, the risk of PTSD in migrant populations decreases over generations, reaching similar proportions by the third generation.

The risk factors for PTSD and the distribution of stressful and traumatic events vary greatly between countries that receive migrants and those that send them, creating a complex relationship. Receiving countries might present diverse challenges, such as different cultures/acculturation, weak social integration, difficulties in daily life, and poor access to healthcare. Sending countries might have backgrounds of political instability, low socioeconomic status, violence, and natural disasters. Several PTSD risk factors are reported in research, including multiple traumatic events, being a victim of violence (e.g., torture, rape/sexual assault, armed conflicts), and economic hardship. Post-migration difficulties also contribute, such as poor social networks (e.g., loneliness, boredom, weak social integration), limited access to counseling services, socioeconomic/political instability (e.g., lack of legal immigrant status, unemployment), detention, communication difficulties, and acculturative stress related to post-migration experiences, among others.

Communication skills are a topic that can lead to different interpretations of the same evidence. Migrants frequently express concern about these skills, as better language ability allows for improved work, educational opportunities, and appropriate medical care. However, Chu and colleagues proposed an interesting perspective: better skills in the receiving country's language predicted worse PTSD outcomes. This could be related to higher expectations for coping with migration compared to those with poor fluency. Porter & Haslam reported a similar finding: refugees with higher socioeconomic status before migration had worse mental health outcomes due to a sharper drop in their status. Considering all these risk factors, and that they are unevenly distributed globally and over time, it is important to consider each population in its unique historical context and their personal experiences in both their previous and current homes.

Limitations of the Current Data

Given these unique circumstances, research on migrants' PTSD outcomes and mental health more broadly has some limitations. First, interviews and evaluations in many studies were often conducted in the host country's language, which could lead to misunderstandings and affect the study's accuracy. Language and cultural barriers can be overcome by using assessment tools in the migrant's native language, administered by someone from the same cultural background, as Norris & Aroian did; this can make participants feel more comfortable. Once this barrier is overcome, as mentioned earlier, the risk of mental health problems depends on historical context and personal experiences. Therefore, the evidence found in research should not be seen as unchanging but rather as something that requires regular review and thorough assessment, including the biological, psychological, social, spiritual, and subjective aspects of experiences and mental illness. Lastly, in addition to needing larger samples, it is important to note that most studies included had inherent sampling bias. Song and colleagues suggested that poor mental health could hinder functioning in affected individuals, which might prevent them from seeking help. Considering this, and that most studies enroll voluntary participants, it is possible that the results may have underestimated the true extent of the issues. Other limitations to be aware of include potential issues with validating cross-cultural assessment instruments and biases related to recall and self-selection.

Discussion

Considering the immense challenge of providing mental healthcare to a large number of international migrants, research on this topic remains underdeveloped. Overall, available studies suggest that migration can be a stressful experience and can expose individuals to one or more traumatic experiences, including complex trauma (like sexual violence and war trauma). Some researchers argue for a selection hypothesis, suggesting that the higher rate of mental disorders in migrants is due to predisposed individuals selectively migrating. However, long-term data now contradict this theory. Many researchers have stated that for millions of people, migration is becoming a process that involves intense stress, which can overwhelm human adaptive capacity and trigger mental or physical problems, symptoms, or illnesses. Some have even proposed a distinct condition of suffering typical of immigration-related stress: "Ulysses syndrome" or the "immigrant syndrome of chronic and multiple stress," which resembles an adjustment disorder with cultural aspects. In this sense, the migrant syndrome of chronic and multiple stress would belong more to the field of mental health than to actual mental illness, since immigrants do not necessarily suffer from mental illness but rather experience a range of symptoms caused by multiple stressors. If the situation linked to these stressful events is not resolved, there is a risk that mental illness may develop. Recognizing this framework of adaptation to migration-related stress highlights many possibilities along a continuum of adjustment, ranging from complete adaptation (or reported emotional growth through the grieving of the migratory experience) to the immigrant syndrome of chronic and multiple stress, and even further, to the development of mental illness (e.g., PTSD if trauma was involved).

Therefore, considering that migrant populations are more affected by PTSD (and other psychiatric disorders like major depression), which is linked to poorer functioning, it is essential for the healthcare system and providers to focus on the mental health of migrants in relation to trauma exposure. Characteristics of the receiving country also influence migrants' mental health. For instance, migrants living in areas with a low ethnic density face an increased risk of psychosis. Generally, treatment adherence is lower in immigrants, which is an important factor to consider when offering services to this group. Differences across studies in terms of population, assessment tools for traumatic experiences and mental health outcomes, and the use of convenience sampling methods are limitations that should be kept in mind when interpreting these findings. Many mental health studies, such as those on suicide, often exclude recent immigrants (which is partly relevant given that a culture-specific adjustment syndrome should not be treated as a mental disorder), but more specific research on migration and mental health is still needed. Clinically significant aspects of stress-related disorders, such as cognitive deficits, also remain largely unexplored among migrants. Nevertheless, the significantly higher prevalence of PTSD among migrants, especially refugees, leaves little doubt that these experiences are strongly linked to this specific illness.

Berry's acculturation model suggests that the more marginalized migrants are in their new community, the greater their risk for mental health problems. In general, difficulties with social adjustment are often cited as a predictor of mental illness, substance relapse, and low treatment adherence in various mental disorders.

Mental health services in Brazil that work with migrants need to be prepared for a population facing specific challenges related to acculturation stress and potential trauma, as well as a profile of lower treatment adherence and a greater overall incidence of mental illness. Clinicians must also possess cultural awareness and sensitivity to differentiate between genuine mental illness (such as PTSD) and psychosocial adjustment difficulties (such as Ulysses syndrome) to provide appropriate treatment.

Summary

People who move to a new country to live or work are called migrants. People in the new country often call them immigrants. Many people, about 244 million worldwide, have left their home countries because of war, poverty, or to find a better life. In Brazil, about 117,745 people from other countries live there. Most are from Bolivia, Colombia, Argentina, China, Portugal, and Paraguay. They move to Brazil to find jobs, be with family, or for safety. Doctors, nurses, and other helpers will meet these migrants in places like schools, hospitals, and community centers. These helpers need to know how to work with migrants.

Migrants often face things that can hurt their mental health. These include stressful or upsetting experiences like being treated unfairly because of their race, violence in cities, bad treatment by police, being forced to leave or be separated from family, being held in detention, or being sent back to their home country. These stressful and upsetting events can lead to mental health problems like a lot of sadness, extreme worry after a scary event (PTSD), confused thinking, or thoughts of harming oneself.

Stress is when a situation causes a person's body and mind to react. The person then has to learn how to deal with the new situation. When a person cannot deal with the stress, they might develop a mental health problem. Moving to a new country often causes a lot of ongoing stress because a person constantly has to adjust to new things.

It is important to understand how moving and stress affect mental health, especially PTSD, in Brazil. This will help create ways to prevent problems and offer culturally right help to migrants early on. This paper looked at what has been written about migration and stress, focusing on PTSD. It also talks about what this means for mental health services in Brazil.

Methods

This study looked for articles written in Portuguese, English, Spanish, or French up to the year 2017. The articles were found in several large online libraries like PubMed and SciELO. The words used to search were migration, mental health, mental health services, stress, posttraumatic stress disorder, and trauma. The study included original research, reviews, and summaries. They also looked at the lists of references in the articles they found to find even more helpful papers.

Results

Stress and migration

Many experts agree that moving to a new country brings its own kinds of stress. This is because people have to get used to a new country and its culture. This can affect many parts of a person's life, including their mental health. Many experts say that migrants are more likely to have health problems, especially mental ones. They may feel more worried or hopeless about the future. This can happen because they lose their support system and feel alone if they do not know the language or culture well.

One kind of stress that comes with moving is that it lasts a long time. Some of these stresses include feeling like they do not belong anywhere, having bad living conditions (like no papers or bad housing), changes in language and culture, loneliness, not reaching their goals for moving, and the daily struggle to survive. From a certain point of view, moving can be like grieving a loss. A person moves away from family, friends, language, culture, country, social standing, and the groups they belong to. They might also feel unsafe. Some experts describe how moving can lead to different kinds of grief:

• Simple grief: When people can deal with the changes well.

• Complicated grief: When people have serious problems dealing with the move.

• Extreme grief: When the problems are too big to handle, leading to what is called "immigrant syndrome with chronic or multiple stress" or "Ulysses syndrome." This syndrome was named after the Greek story of Ulysses, who had a long, hard journey home.

Ulysses syndrome includes four types of problems:

1. Feeling down: Sadness, crying, feeling guilty, and sometimes thoughts of dying.

2. Feeling worried: Being tense and nervous, worrying too much, being easily annoyed, and not sleeping well.

3. Body problems: Headaches, tiredness, and aches in muscles, stomach, and chest.

4. Thinking problems: Trouble remembering, trouble paying attention, and feeling lost about time and place.

Stress and acculturation

Acculturation is a big process that changes many parts of a migrant's life. This includes language, their cultural identity, what they believe, their habits, how they get along with others, and even what they eat. Acculturation can happen in steps. First, migrants might learn the new language, then they might change how they act and join in the new culture. In some places, like work or school, they might mostly experience the new country's culture. In other places, like their home or neighborhood, they might mainly experience their home country's culture. This means acculturation is about living with both cultures. This can give them different kinds of help, including what they need to stay mentally healthy.

Psychological acculturation is the way immigrants start to adapt to the new culture when they arrive. Behavioral acculturation is how much immigrants take part in their old culture or the new culture. Besides learning new ways, adult migrants can keep up with their home culture. They might make friends with other migrants from their country, share common interests, eat their traditional food, and read things in their first language.

One model of acculturation talks about four ways people adapt:

1. Integration: The person keeps parts of their old culture but also learns parts of the new one. This works best in places that welcome different cultures and have little prejudice.

2. Assimilation: The person does not want to keep their old culture and fully takes on the new culture. They care most about fitting into the new place.

3. Separation: The person only values their old culture and does not want to join the new country's culture.

4. Marginalization: The person does not keep their old culture and does not feel a part of the new culture. They feel left out. This can lead to a lot of worry and feeling lost.

Education, good jobs, and people who support them can help migrants adapt well. But big differences between the old and new cultures can mean a lot of learning and can cause ongoing problems.

Problems from acculturation can include changes in how men and women act, disagreements between parents and children, family fights, children having to take on adult roles, confusion about identity, loneliness, and feeling alone. It is common for children in migrant families to adapt to the new culture faster than their parents. This can lead to arguments about friends, dating, marriage, and jobs. Children might not tell their parents about their problems because they think their parents do not understand the new culture well enough to help. Sometimes, older children of immigrants might have to translate for their parents or help them understand the new country. Older adult migrants are often the most likely to have mental health problems, except for those who have been through war or torture.

Disagreements due to acculturation often lead immigrant families to get help from mental health services. Even immigrants who have lived in a new country for a long time and seem to have adopted its ways might still feel strongly connected to their old culture. Mental health services should have programs to help immigrants get used to the new country, learn its ways, and keep their connection to their old country and culture.

Traumatic events in migrants

It is hard to get mental health services to migrants not just because of language and culture, but also because of the upsetting things they have been through. These upsetting events can happen before they move, during the move, or even after they have settled in the new place.

How much an upsetting event affects mental health depends on how often it happens, how bad it is, and how long it lasts. One study found that the more upsetting experiences related to war a person had, the more likely they were to have mental health problems, including PTSD. Another study found that many migrants with refugee status and PTSD had strange experiences, like hearing voices or believing things that were not true. These were more common in people who had been tortured or held prisoner. Bad experiences like childhood abuse and upsetting events all work together in complex ways to increase the risk of confused thinking. Moving is linked to more severe confused thinking, and refugees are more likely to have certain types of confused thinking. Some experts believe that the higher risk of certain mental illnesses in migrants is found in those who are least successful and face the most unfair treatment. They also think this is why childhood trauma is a risk factor. Other experts say that being treated badly, especially if it includes being physically hurt, has the strongest effect. This shows that facing hostility, threats, and violence can lead to a higher risk of confused thinking because it causes more paranoia and false beliefs.

One study also found that how much money a person made after moving did not affect their risk of PTSD. But it did affect their risk of deep sadness, where having less money was a clear risk factor. Still, most studies show that how bad the upsetting events were (especially war trauma) affects mental health now, even after considering things that happened after the move.

Posttraumatic stress disorder (PTSD) and migration

PTSD is a serious mental illness that can make life very difficult for individuals and their families, as well as for society and healthcare. For a person to be diagnosed with PTSD, they must have experienced a traumatic event. It is the only mental illness that requires a scary event to happen before symptoms appear. Specific signs, like having flashbacks, being easily startled, avoiding certain things, and having negative thoughts or feelings, must last for at least four weeks after the traumatic event. Many things can increase the risk of getting PTSD. These include how bad or often the trauma happened, a person's genes, body reactions, brain differences, and how strong they are. Things that happen during and after the trauma also matter, like their money situation, social connections, and difficulties after the event.

One large study found that out of many studies on PTSD between 1990 and 2007, about 47% of people had PTSD. The rate was almost twice as high for refugees compared to people who moved for work. This is likely because refugees often face more violence, war, and political persecution, which are often why they move. As mentioned, migrants often go through a series of upsetting experiences in their home country, during their journey, or when they are settling in a new place. So, it is not surprising that mental health problems, including PTSD, are common in this group. This very high rate in migrants shows how important it is to pay close attention to their mental health. In the general adult population, about 3% of people have PTSD at any given time. Interestingly, the risk of PTSD in migrant families goes down over generations, becoming similar to the general population by the third generation.

The risks for PTSD and the kinds of stressful and upsetting events are very different in countries that receive migrants and countries that send them. This creates a complex situation. Countries that receive migrants might have different challenges like new cultures, trouble fitting in, daily life problems, and limited access to healthcare. Countries that send migrants might have problems like unstable governments, little money, violence, and natural disasters. Many things have been reported as risk factors for PTSD. These include many upsetting events, being a victim of violence (like torture or war), and money problems. Difficulties after moving also play a role, such as not having good social connections (feeling lonely or bored), not getting help, unstable money or politics (like not having legal papers or a job), being held in detention, trouble communicating, and stress from adapting to a new culture.

Communication skills are important. Migrants often say that better language skills would help them get better jobs, education, and medical care. However, some studies have shown that better language skills in the new country could actually mean worse PTSD outcomes. This might be because people with better language skills have higher hopes for dealing with their move compared to those who do not speak the language well. A similar finding was that refugees who had more money before moving had worse mental health problems because their status dropped so sharply. With all these risk factors, which vary greatly around the world and over time, it is important to consider each group of people in their unique history and personal experiences both in their old and new homes.

Limitations of the current data

There are some things that limit research on migrants' PTSD and mental health in general. First, interviews and checks were often done in the language of the new country. This can lead to misunderstandings and make the studies less accurate. Language and cultural barriers can be overcome by using tests in the migrant's own language, given by someone from the same culture. This can make the person feel more comfortable. Once this barrier is overcome, as said before, the risk of mental health problems depends on history and personal experiences. So, what is found in studies should not be seen as set in stone. It needs to be checked often, and evaluations should look at all parts of a person's experience, including their body, mind, social life, and beliefs. Lastly, besides needing more people in studies, it is important to know that most studies had a problem with how people were chosen. Some experts suggest that poor mental health might stop people from functioning well, which in turn could keep them from seeking help. Since most studies use people who volunteer, it is possible that the results do not show the full picture. Other things to be aware of include whether tests used for different cultures are accurate and problems with remembering past events or choosing to be in a study.

Discussion

There are many migrants around the world, but not much has been studied about how to provide them with mental healthcare. What we do know suggests that moving can be very stressful. It can expose people to one or many upsetting experiences, including severe trauma like sexual violence or war. Some experts used to think that the higher rates of mental illness in migrants were because only people who were already likely to have problems chose to migrate. However, newer studies do not support this idea. Many experts now say that for millions of people, migration involves such intense stress that it can overwhelm a person's ability to cope and lead to mental or physical problems. Some have even suggested a special kind of suffering unique to the stress of immigration, called "Ulysses syndrome" or "immigrant syndrome of chronic and multiple stress." This is like an adjustment problem with cultural aspects. In this way, the immigrant syndrome of chronic and multiple stress is more about overall mental well-being than a mental illness itself, because immigrants do not necessarily have a mental illness but experience many symptoms caused by too much stress. If the stressful situation is not fixed, there is a risk that a mental illness might develop. Understanding how people adapt to the stress of migration shows a range of possibilities, from fully adapting (or even growing emotionally from the experience) to the immigrant syndrome of chronic and multiple stress, and even to developing a mental illness (like PTSD if there was trauma).

Because migrants, especially refugees, are more affected by PTSD and other mental health problems like severe sadness, which can make it hard to function, it is very important for the healthcare system and providers to pay attention to their mental health in relation to trauma. Where a migrant lives in the new country also affects their mental health. For example, migrants living in an area with few people from their own ethnic background have a higher risk of confused thinking. Generally, immigrants are less likely to stick with their treatment, which is something to consider when offering help. Differences in studies, such as the groups of people studied, the tools used to measure upsetting experiences and mental health, and the way people were chosen for studies, are important to remember when understanding these findings. Many mental health studies, like those on suicide, often leave out people who recently moved (which is partly relevant since an adjustment syndrome specific to a culture should not be treated as a mental disorder). But more specific research on migration and mental health is still needed. Important parts of stress-related problems, like thinking difficulties, are also not well understood in migrants. However, the much higher rate of PTSD in migrants, especially refugees, strongly suggests that these experiences are linked to this specific illness.

The idea of acculturation suggests that the more migrants feel left out in their new community, the higher their risk for mental health problems. Generally, problems adjusting socially are often linked to mental illness, going back to drug use, and not sticking to treatment for various mental illnesses.

Mental health services in Brazil that work with migrants need to be ready for people with special challenges related to the stress of adapting to a new culture and possible trauma. They also need to be aware that migrants might be less likely to follow through with treatment and generally have more mental health issues. Helpers must also be aware of different cultures and be sensitive enough to tell the difference between a real mental illness (like PTSD) and problems adjusting to a new social situation (like Ulysses syndrome). This way, they can offer the right kind of help.