Epidemiology and Risk Factors

CHAPTER 47 Epidemiology and Risk Factors

Changing Immigration Patterns

Study of the mental health effects of immigration is often cited as beginning in the 1930s with the work of Odegaard,2 who studied the prevalence of schizophrenia among Norwegian immigrants to Minnesota compared with a sample of Norwegians who remained in the home country. He found more schizophrenia among the immigrants, and the finding of greater mental health problems among immigrants has been common in studies of diverse populations ever since.

However, much has changed since Odegaard completed his work. Immigration has changed from predominantly Europeans to those from developing or disadvantaged countries in South America, Africa, the Middle East, Asia, and Eastern or Central Europe. This has meant far greater linguistic, cultural, and religious differences from the mainstream population. Reasons for immigrating have also changed. More are likely to be emigrating because of fear and traumatic experiences than only for economic advantage. Although economic migrants flow across the southern border of the US, many refugees and asylum seekers have left their home countries after experiencing torture or other influential traumatic events. While few in the early part of the twentieth century sought refuge from persecution, many immigrants are now refugees, asylum seekers, or otherwise undocumented immigrants who have been traumatized. The phases of immigration have also become more complicated. Rather than traveling from the home country to the country of final resettlement, many immigrants now have long transitional periods in intermediate countries or refugee camps prior to reaching their final destination. These transitional periods are often filled with stressors, danger, and traumatic experiences in their own right.3 Intermediate immigration status, e.g. being an undocumented or asylum applicant, may exacerbate mental health problems.4,5 Final resettlement usually involves poverty, anti-immigrant sentiment, and discrimination based on racial, ethnic, gender, or religious identity. This is further complicated by the increase in terrorism worldwide, and authorities in resettlement countries are becoming more fearful of those who emigrate from countries where terrorists reside.

Consequently, all of these changes in immigration have implications for potentially increased problems with mental health and integration for immigrant populations. Questions which still require answers are how frequent is mental illness in each phase of migration, what are the precipitants, and what can we do to help minimize the occurrence of mental illness for immigrants?

Prevalence of Selected Psychiatric Disorders

High rates of mental health problems have been well documented in various refugee and immigrant groups. Most studies demonstrate a high prevalence of post-traumatic stress, anxiety, depression, and somatization.69 Wide variations reported in the prevalence of post-traumatic stress disorder (PTSD) (4–86%) and depression (5–31%), for instance, may be ascribed to a number of factors affecting refugees before migration, in the process of flight, and during and after the resettlement, as well as to differences in data collection, analysis, and interpretation. Porter and Haslam10 used a worldwide study sample in a meta-analysis, compared refugees with nonrefugee comparison groups and concluded that the sociopolitical context of the refugee experience is associated with refugee mental health and humanitarian activities that influence these conditions positively.


Many refugees suffer from multiple mental health problems. Patients with PTSD are also frequently diagnosed with major depressive disorder (MDD). Marshall et al.11 found high comorbidity between these disorders: 71% of subjects in their study who had PTSD also met criteria for MDD, and 86% of those with major depression met criteria for PTSD. They also reported high comparability in risk factors for depression and PTSD.

While PTSD and comorbid PTSD/depression have similar clinical presentation, results of some studies support the existence of depression as a separate clinical entity.12 According to these authors, major depression and PTSD are independent sequelae of traumatic events, which have similar prognosis, and interact to increase distress and dysfunction. In one study, patients with comorbid MDD and PTSD were more likely to attempt suicide, and women with both disorders were more likely to attempt suicide than men with the same diagnosis.13

High rates of mental health problems are reported both in newly arrived asylum seekers and refugees and in those who resettled many years ago. In a prospective study of mass evacuated Kosovo Albanians, participants with PTSD had significantly lower cortisol levels. Depressive symptoms and aggression followed the same pattern as PTSD, with increasing symptom levels, while sense of coherence scores decreased. Women had worse outcomes regarding both PTSD and depression.1416 Aggression among refugees is often neglected in the clinical context. In Western-oriented culture, depression is more acceptable. Thus, aggression in traumatized populations, especially its consequences, needs to be evaluated in more detail. Specifically, Carlson and Rosser-Hogan17 reported that a high proportion of recently arrived Cambodian refugees suffer from severe psychiatric symptoms (86% PTSD; 96% high dissociation scores; 80% clinical depression), and there is a relationship between the amount of trauma they experienced and the severity of these symptoms.

At the same time, Marshall et al.11 found that two decades after the end of the Cambodian War and resettlement of refugees in the United States, Cambodians continued to have high rates of psychiatric disorders associated with trauma. In their study, 62% of Cambodian refugees who came to the United States 20 years ago met DSM-IV diagnostic criteria for PTSD in the past year and 51% met diagnostic criteria for MDD.

Risk Factors

Mental health problems may come just as much from how refugees are approached in the resettlement country as from their past, although in most cases they tend to be attributed to their past experiences. Below, we consider several factors affecting refugees’ mental health in all stages of their refugee experience.


Of particular concern is political violence. Whether occurring overtly through war and armed conflict, or covertly through the sustained and institutionalized repression of a group of people, political violence includes many violence types such as war-related violence, torture, sexual violence, forced disappearances, and extrajudicial killings. Many, if not most, refugees and asylum seekers have experienced significant pre-migration political violence, including torture, as evidenced by prevalence studies in clinics and community samples.5,1821

In a systematic sample of Latino immigrant adults attending three community-based primary care clinics in Los Angeles, Eisenman and colleagues22 found that, overall, 54% screened positive for political violence exposure: 8% reported torture, 15% witnessed violence against their family, 27% reported forced disappearance of family members, 26% witnessed mass violence, and 32% reported their life endangered by attacks with bombs or heavy weapons. Five percent reported witnessing torture or an execution and 3% (6 women and 1 man) reported being raped. These results are consistent with earlier estimates from one urban medical clinic in New York City in which 6% of all foreign-born patients had experienced political torture.23 These estimates are not surprising given that immigrants and refugees widely use public health clinics.24 These groups experience similarly high rates of intimate partner violence25 and community violence.26

Torture’s effect may be additive to other forms of trauma. Jaranson et al.,9 in their study of Somali and Oromo refugees in Minnesota, reported that in their sample torture survivors were more likely than other refugees to experience physical and psychological problems. Jaranson et al. found torture prevalence ranged from 25% to 69% by ethnicity and gender, higher than usually reported, and torture survivors had more physical and mental health problems.

One of the surprising findings in Jaranson’s study was the relationship between gender and torture prevalence. Although it is commonly assumed that men are the primary target of organized violence and experience more psychological problems, some studies of the relationship between gender and trauma yield different results. Specifically, in the above-mentioned study, women were found to be as likely subjected to torture as men. As an example from clinical experience, Vietnamese men who were exposed to the most horrific forms of torture in concentration camps following the Vietnam War usually were the ones who were granted political asylum in the United States through the ‘Humanitarian Operation’ program. In the meantime, the ordeals their wives had to go through remained to a large degree unnoticed until recently. Gender differences for psychiatric vulnerability among traumatized populations require further investigation for their relationship both to trauma and to psychosocial factors.

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Aug 11, 2016 | Posted by in INFECTIOUS DISEASE | Comments Off on Epidemiology and Risk Factors

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