The aims of this meta-analysis are (i) to estimate the pooled relative risk (RR) of developing non-affective psychotic disorder (NAPD) and affective psychotic disorder (APD) among migrants and their children; (ii) to adjust these results for socioeconomic status (SES); (iii) to examine the sources of heterogeneity that underlie the risk of NAPD.

We included population-based incidence studies that reported an age-adjusted RR with 95% confidence interval (CI) published 1 January 1977–12 October 2017 and used a random-effects model.

We retrieved studies performed in Europe (n = 43), Israel (n = 3), Canada (n = 2) and Australia (n = 1). The meta-analysis yielded a RR, adjusted for age and sex, of 2.13 (95% CI 1.99–2.27) for NAPD and 2.94 (95% CI 2.28–3.79) for APD. The RRs diminished, but persisted after adjustment for SES. With reference to NAPD: a personal or parental history of migration to Europe from countries outside Europe was associated with a higher RR (RR = 2.94, 95% CI 2.63–3.29) than migration within Europe (RR = 1.88, 95% 1.62–2.18). The corresponding RR was lower in Israel (RR = 1.22; 0.99–1.50) and Canada (RR = 1.21; 0.85–1.74). The RR was highest among individuals with a black skin colour (RR = 4.19, 95% CI 3.42–5.14). The evidence of a difference in risk between first and second generation was insufficient.

Positive selection may explain the low risk in Canada, while the change from exclusion to inclusion may do the same in Israel. Given the high risks among migrants from developing countries in Europe, social exclusion may have a pathogenic role.

The value of the nosological distinction between non-affective and affective psychosis has frequently been challenged. We aimed to investigate the transdiagnostic dimensional structure and associated characteristics of psychopathology at First Episode Psychosis (FEP). Regardless of diagnostic categories, we expected that positive symptoms occurred more frequently in ethnic minority groups and in more densely populated environments, and that negative symptoms were associated with indices of neurodevelopmental impairment.

This study included 2182 FEP individuals recruited across six countries, as part of the EUropean network of national schizophrenia networks studying Gene–Environment Interactions (EU-GEI) study. Symptom ratings were analysed using multidimensional item response modelling in Mplus to estimate five theory-based models of psychosis. We used multiple regression models to examine demographic and context factors associated with symptom dimensions.

A bifactor model, composed of one general factor and five specific dimensions of positive, negative, disorganization, manic and depressive symptoms, best-represented associations among ratings of psychotic symptoms. Positive symptoms were more common in ethnic minority groups. Urbanicity was associated with a higher score on the general factor. Men presented with more negative and less depressive symptoms than women. Early age-at-first-contact with psychiatric services was associated with higher scores on negative, disorganized, and manic symptom dimensions.

Our results suggest that the bifactor model of psychopathology holds across diagnostic categories of non-affective and affective psychosis at FEP, and demographic and context determinants map onto general and specific symptom dimensions. These findings have implications for tailoring symptom-specific treatments and inform research into the mood-psychosis spectrum.

Migration is a risk factor for the development of schizophrenia.

To examine whether migration is also a risk factor for bipolar affective disorder, unipolar depressive disorder and mood disorders in general.

Medline was searched for population-based incidence studies concerning mood disorders among migrants and mean relative risks were computed using a mixed-effects statistical model.

Only a few studies of unipolar depressive disorder were retrieved. The mean relative risk of developing bipolar affective disorder among migrants was 2.47 (95% C11.33–4.59). However, after excluding people of African-Caribbean origin in the UK this risk was no longer significantly increased. The mean relative risk of mood disorders of unspecified polarity was 1.25 (95% CI 1.04–1.49) and that of any mood disorder was 1.38 (95% CI 1.17–1.62).

There is no conclusive evidence for a large increase in the risk of mood disorders associated with migration.

Black individuals in the UK have higher rates of contact with psychiatric emergency services than their White counterparts. It is unknown whether this is also the case in other European countries.

To compare the risk of contact with psychiatric emergency services and of compulsory admission between immigrant groups to The Netherlands and Dutch natives, and to determine the unique contribution of ethnicity to compulsory admission.

Study of 720 people referred to emergency psychiatric services in Greater Rotterdam, The Netherlands.

The relative risks (RRs) for contacts with psychiatric emergency services, for having a psychotic disorder and for compulsory admission were significantly higher in most immigrant groups. Moroccans, Surinamese and Dutch Antilleans had the highest risks of compulsory admission. After controlling for symptom severity, danger, motivation for treatment and level of social functioning, non-Western origin was no longer associated with compulsory admission.

Non-Western immigrant groups were overrepresented in psychiatric emergency care and were admitted compulsorily more frequently, possibly owing to a different clinical presentation.

No study outside the UK has examined the diagnostic stability of psychotic disorders in a population-based sample.

To determine diagnostic stability in a Dutch population-based psychosis incidence cohort, to examine the frequencies of diagnostic shifts to and from schizophrenic disorders and to report the revised relative risks of schizophrenic disorders for immigrants.

A 30-month follow-up study assessed the cohort (n=181) by means of face-to-face diagnostic interviews.

Diagnostic stability of schizophrenic disorders was high (91%), but lower for other psychotic disorders. At follow-up, the initial diagnosis was adjusted to schizophrenic disorder more often than that the reverse occurred. Almost half (49%) of the patients who were not initially diagnosed as having a schizophrenic disorder received this diagnosis at follow-up. The relative risks for most immigrant groups were stable.

Schizophrenic disorders are underdiagnosed, rather than overdiagnosed, at first presentation.

It has been suggested that prenatal exposure to maternal stress increases the risk of subsequently developing schizophrenia.

The five-day invasion and defeat of The Netherlands by the German army in May 1940 constituted a severe, well-circumscribed national stressful event. Individuals exposed and non-exposed to this stressor in the first, second and third trimester of pregnancy were followed up for lifetime schizophrenia outcome through the National Psychiatric Case Register.

Cumulative incidence of schizophrenia was higher in the exposed cohort (risk ratio (RR): 1.15, 95% CI: 1.03–1.28), especially in those exposed in the first trimester (RR: 1.28, 95% CI: 1.07–1.53). Significant interaction with gender was apparent in second trimester exposed cohorts (RR men: 1.35, 95% CI: 1.05–1.74; RR women: 0.83, 95% CI: 0.61–1.12).

Maternal stress during pregnancy may contribute to the development of vulnerability to schizophrenia. The apparent longer window of exposure in male foetuses may be related to the slower pace of male early cerebral development.