Immigrants from the Caribbean and refugees from East Africa and South Asia are up to twice as likely to experience a psychotic disorder compared to the general population in Canada, according to a large study in CMAJ (Canadian Medical Association Journal).
“Given that Canada is currently experiencing a rapid growth in the population of foreign-born citizens — one of the highest rates of any Western nation — the mental health status of immigrants and refugees should be a national priority,” writes Dr. Kelly Anderson, an assistant professor at Western University, London, Ontario, and a fellow at the Institute for Clinical Evaluative Sciences (ICES).
For the study, Anderson and her co-authors analyzed the health data for 4,284,694 Ontario residents aged 14-40. The goal was to determine whether first-generation immigrants and refugees to Canada were at higher risk of schizophrenia or schizoaffective disorder.
The researchers, who tracked the participants over a 10-year period, found that almost 10 percent of the population (418,433) were migrants born outside Canada, and almost 23 percent (95,148) of these migrants were refugees.
The incidence of psychotic disorders was 55.6 per 100,000 in the general population, 51.7 among immigrants and 72.8 among refugees. Some immigrant groups (from Northern and Southern Europe and East Asia, for example) had lower rates than the general population.
Immigrants from the Caribbean and Bermuda had the highest rates of schizophrenia, as did refugees from East Africa and South Asia.
“Migrant status, in particular refugee status, needs to be considered as an important risk factor for psychotic disorders in Ontario,” write the authors.
“The differential rates cannot be explained by variations in the country of origin, and the selective migration of people who have an increased risk is increasingly being refuted as a plausible explanation,” write the authors.
“The pattern we observed in Ontario suggests that psychosocial factors associated with the migratory experience and integration into Canada may contribute to the risk of psychotic disorders.”
The researchers hypothesize that experiences of discrimination and racism may explain the higher rates of psychotic disorders in some immigrant groups, as indicated by earlier research.
Refugees may be more vulnerable to psychosis for a variety of reasons, including earlier trauma in their home countries as well as obstacles in finding housing, jobs, or health care when settling in Canada.
“Perhaps the most striking finding from the study is that rates of psychosis were not elevated consistently among nonrefugee first-generation migrants relative to the general population,” writes Kirkbride.
He notes that the lack of an elevated psychosis risk among all immigrants may be because there are other non-immigrant ethnic groups that are also at greater risk for schizophrenia.