Table 1.

Summary of Evidence on Specific Candidate Explanatory Factors for the High Rates of Psychosis in Migrant and Minority Ethnic Groups

Candidate Explanatory Factorsa	Number of Studies	Findings	References
Misdiagnosis	3	−, −, −	16–18
Selective migration	2	−, −	28,29
Genetic	3	−, −, −	31–33
Neurodevelopmental
Viral infection	0	?	—
Obstetric complications	2	−, −	42–44
Vitamin D	0	?	—
Neurological markers	1	−	47,48
Brain structure	1	+	49
Substance use (primarily cannabis)	4	−, −, −, −	52–55
Stressors premigration and during migration	0	?	—
(Psycho)social
Childhood separation from parents	2	+, +	19,59,60
Adult markers of disadvantage	2	+, +	19,59,61
Discrimination—perceived	3b	+, +, +	63–65
Discrimination—reported	1c	+	62
Ethnic identity	2	+, +	66,67
Ethnic density	4	+, +, +, +	70–73
Urbanicity	2	−, −	3,30

Note: Studies are not weighted in any way, and no account is taken of study quality. −, negative finding; +, positive finding; ?, no study with direct evidence for or against. A “−” or “+” is given for each study that has directly investigated the candidate explanatory factor.

^aStudies are only included in this table if they provide direct evidence in relation to a specific explanatory factor. Indirect evidence (eg, absence of high rates in originating countries of migrants suggesting no influence of genetics) is not included.

^bIncludes one study of prevalent cases.

^cA study of prevalent cases.