Non-affective psychosis in refugees

In 2015, 244 million people (3.3% of the world’s population) lived outside their country of origin. This represents an increase of 39% since 2000.1 2 The decision to migrate may be made for economic betterment or (in the case of “refugees”) to escape war, persecution, or natural disaster. Such motives are not of course mutually exclusive. Substantial evidence shows that the risk of non-affective psychosis is increased (by a factor of about 2.5) in migrants compared with the indigenous population.3

In a linked paper (doi:10.1136/bmj.i1030), Hollander and colleagues argue that this increase is due predominantly to exposure to psychosocial adversities.4 They used national register data to carry out a cohort study of more than 1.3 million people in Sweden, in which risk of non-affective psychosis was compared not only between people born in Sweden and migrants to Sweden but also between refugees and non-refugees within the migrant group. They hypothesised that, because …