The trauma of running away from persecution, war and natural disasters can leave permanent scars on an individual. A latest study has highlighted the extent of the effect such life experiences can have on refugees.

As per a study of 1.3 million people in Sweden, refugees are highly vulnerable to suffering psychotic disorders, like schizophrenia, as compared to the native residents and other migrants.

Published on Tuesday in the journal BMJ, the research said that refugees have three times more chances of experiencing schizophrenia and other psychoses than native-born Swedes.

It has also been found that refugees are also two-thirds as likely of contracting such disorders in comparison to people who have come from the same areas but due to other reasons, like economic factors.

In a release, lead author Anna-Clara Hollander of Sweden's Karolinska Institute said that the severely increased risk among refugees have indicated that life events are a major risk factor for schizophrenia and other psychoses.

Already, refugees are known to be at high risk of contracting post-traumatic stress disorder and depression. However, study researchers said that their study is the first ever to look at the risk of schizophrenia and other psychoses.

The data used by the researchers belonged to Sweden's national registry, which keeps a track of immigration and health status for people. The study included 1.3 million people who took birth after 1983, and were tracked from 14th birthday onwards till 2011 end. In this group, there were 3,704, who experienced a psychotic disorder.

The participants included in the study have migrated from four main areas, including Middle East and North Africa, sub-Saharan Africa, Asia and Eastern Europe, including Russia.

Study co-senior author James Kirkbride of the University College London, said, “These differences cannot be explained by other, important alternative explanations like differences in age, sex, income or urban residency”.