Refugees face a substantially higher risk of psychotic disorders, including schizophrenia, compared to non-refugee migrants from the same regions of origin, finds a study published in The BMJ.
The humanitarian crises in Europe, the Middle East, north Africa, and central Asia have led to more displaced people, asylum seekers, and refugees worldwide than at any time since the second world war.
Refugees are known to be at an increased risk of mental health problems, such as post traumatic stress disorder and common mental disorders, compared to non-refugee migrants, but little is known about their risk of psychosis.
So a team of researchers from the Karolinska Institutet and UCL carried out a study to determine the risk of schizophrenia and other non-affective psychotic disorders among refugees, compared to non-refugee migrants, and the general Swedish population.
The researchers used a linked national register data to examine more than 1.3 million people in Sweden, and tracked diagnoses of non-affective psychotic disorders among the population.
On a per capita basis, Sweden has granted more refugee applications than any other high-income country, and in 2011, refugees constituted 12% of the total immigrant population.
The cohort included people born to two Swedish-born parents, refugees, and non-refugee migrants from the four major refugee generating regions: the Middle East and north Africa, sub-Saharan Africa, Asia, Eastern Europe and Russia.
Results showed 3,704 cases of non-affective psychotic disorders during the 8.9 million person years of follow up.
Refugees granted asylum were on average 66% more likely to develop schizophrenia or another non-affective psychotic disorder than non-refugee migrants. In addition, they were up to 3.6 times more likely to do so than the Swedish-born population.
Incidence rates for non-affective psychosis were 385 per million in those born in Sweden, 804 per million in non-refugee migrants, and 1264 per million in refugees.
The increased rate in refugees was significant for all areas of origin except sub-Saharan Africa, for whom rates in both groups were similarly high relative to the Swedish-born population.
One possible explanation is "that a larger proportion of sub-Saharan Africa immigrants will have been exposed to deleterious psychosocial adversities before emigration, irrespective of refugee status," suggest the authors.
Alternatively, it's also possible that "post-migratory factors, such as discrimination, racism, and social exclusion" may explain these high rates.
Overall, they say "our findings are consistent with the hypothesis that increased risk of non-affective psychotic disorders among immigrants is due to a higher frequency of exposure to social adversity before migration, including the effects of war, violence, or persecution."
They add the findings emphasise "the need to take the early signs and symptoms of psychosis into account in refugee populations, as part of any clinical mental health service responses to the current global humanitarian crises."
In a linked editorial, Cornelius Katona, medical director at the Helen Bamber Foundation, says "a robust mental health response to the refugee 'crisis' must lie in a combination of clinical vigilance, recognition of vulnerability factors, and above all, a determination to minimise the aggravating effects of post-migration experiences."