Migration and schizophrenia.

PURPOSE OF REVIEW An exploration of the evidence that a history of migration is a risk factor for schizophrenia and an evaluation of those studies that seek an explanation for this. RECENT FINDINGS A meta-analysis found an increased risk for schizophrenia among first-generation and second-generation migrants and found a particularly high risk for migrants from countries where the majority of the population was Black. The latter finding was confirmed and extended by a large first-contact incidence study in the UK, which found excessive risks for schizophrenia and mania in the African-Caribbean and black-African sections of the population. A very high risk of schizophrenia has also been reported for Moroccan males in the Netherlands. The explanation for these findings is uncertain. Social adversity, racial discrimination, family dysfunction, unemployment and poor housing conditions have been proposed as contributing factors. According to one hypothesis, the chronic experience of social defeat disturbs dopamine function in the brain. SUMMARY A personal or family history of migration is a high risk factor for schizophrenia and there is now strong evidence against selective migration as the explanation. There is an increasing interest in the impact of social stressors on brain functioning and on the pathogenesis of schizophrenia.