Evidence of an excessive gender gap in the risk of psychotic disorder among North African immigrants in Europe: a systematic review and meta-analysis

Purpose: Epidemiological studies in the Netherlands have reported an excessive gender gap in the risk for non-affective psychotic disorder (NAPD) among immigrants from Morocco with a higher risk elevation in males compared to females. We examined the consistency of these findings and their generalizability to immigrants from the Maghreb (Mauritania, Morocco, Algeria, Tunisia and Libya) in other European countries. Methods: Systematic review and meta-analysis. Medline, PsychINFO and EMBASE databases were searched for publications in the period from January 1970 to April 2014. We included incidence and prevalence studies of non-affective psychotic disorder (NAPD) among migrants from the Maghreb in Europe and studies of subclinical psychotic symptoms (SPS) in representative samples. A meta-analysis was performed on the subgroup of incidence studies. Results: Five incidence and three prevalence studies of NAPD, and two prevalence studies of SPS, conducted in the Netherlands (n=7), Belgium (n=1), France (n=1) and Italy (n=1) met our inclusion criteria. Across all research designs, the risks of NAPD and SPS were consistently increased among male, not female immigrants from the Maghreb. The meta-analysis of incidence studies of NAPD yielded male-to-female risk ratios of 5.1 [95 % confidence interval (CI) 3.1–8.4] for migrants from the Maghreb, 2.0 (95 % CI 1.6–2.5) for other migrant groups, and 1.8 (95 % CI 1.3–2.5) for non-migrant Europeans. Conclusions: The marked gender gap in psychosis risk among migrants from the Maghreb appears a consistent finding, foremost among the Moroccan-Dutch. The small number of studies limits the strength of conclusions that can be drawn about countries other than the Netherlands. Achievement–expectation mismatch, social marginalization and an increased prevalence of illicit drug use are possible explanations.