Psychosis risk for parents and siblings of Dutch and Moroccan-Dutch patients with non-affective psychotic disorder

Exploring indigenous ethnic inequities in first episode psychosis in New Zealand - A national cohort study

INTRODUCTION

First episode psychosis (FEP) disproportionately affects rangatahi (young) Māori, the Indigenous people of New Zealand, but little is known about factors contributing to this inequity. This study describes a cohort of rangatahi Māori and young non-Māori with FEP, and explores ethnic differences in incidence rates, and the contribution of deprivation, urbanicity and substance use.

METHODS

Māori and young non-Māori, aged 13-25 at the time of the first recorded psychosis-related diagnoses, were identified from within Statistics NZ's Integrated Data Infrastructure (IDI), between 2009 and 2012. To estimate age-standardised FEP incidence rates, the population-at-risk was estimated using IDI-based usual resident population estimates for 2009-2012, stratified by ethnicity and single year of age. Poisson regression models were used to estimate ethnic differences in FEP incidence adjusted for age, gender, deprivation, and urban-rural area classification.

RESULTS

A total of 2412 young people with FEP (40% Māori, 60% non-Māori) were identified. Māori were younger, and more likely to live in deprived and rural communities and be diagnosed with schizophrenia. Substance induced psychosis was uncommon. The unadjusted age-standardised FEP incidence rate ratio was 2.48 (95% CI: 2.29-2.69) for rangatahi Māori compared with young non-Māori. While adjusting for age, sex, deprivation and urban rural area classification reduced ethnic differences in incidence, rangatahi Māori were still more than twice as likely to have been diagnosed with FEP compared to young non-Māori.

CONCLUSIONS

This study confirms previous findings of elevated rates of psychosis among rangatahi Māori. The difference in rates between Māori and non-Māori were attenuated but remained after adjustment for deprivation and urbanicity.

Age at migration and the risk of psychotic disorders: a systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis of the existing evidence on the association between age at migration and the risk of psychotic disorders.

METHODS

Observational studies were eligible for inclusion if they presented data on the association between age at migration and the risk of psychotic disorders among first-generation migrant groups. We used two random effects meta-analyses to pool effect estimates for each stratum of age at migration relative to (i) a native-born reference category and (ii) the youngest age stratum (0 to 2 years).

RESULTS

Ten studies met inclusion criteria, and five were included in the meta-analysis. The risk of psychotic disorder among people who migrate prior to age 18 is nearly twice as high as the native-born population, with no evidence of effect modification by age strata. People who migrate during early adulthood (19 to 29 years) have a similar risk of psychotic disorder as the native-born population (IRR = 0.93, 95% CI = 0.60, 1.44) and a lower risk relative to those who migrate during infancy (0 to 2 years) (IRR = 0.58, 95% CI = 0.33, 1.04).

CONCLUSIONS

Migrant status is one of few well-established risk factors for psychotic disorder, yet we have limited understanding of the underlying etiology. The findings of this review advance our understanding of this association and identify high-risk groups to target for intervention.

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.

Childhood trauma mediates the association between ethnic minority status and more severe hallucinations in psychotic disorder

BACKGROUND

Ethnic minority status and childhood trauma are established risk factors for psychotic disorders. Both are found to be associated with increased level of positive symptoms, in particular auditory hallucinations. Our main aim was to investigate the experience and effect of childhood trauma in patients with psychosis from ethnic minorities, hypothesizing that they would report more childhood trauma than the majority and that this would be associated with more current and lifetime hallucinations.

METHOD

In this cross-sectional study we included 454 patients with a SCID-I DSM-IV diagnosis of non-affective or affective psychotic disorder. Current hallucinations were measured with the Positive and Negative Syndrome Scale (P3; Hallucinatory Behaviour). Lifetime hallucinations were assessed with the SCID-I items: auditory hallucinations, voices commenting and two or more voices conversing. Childhood trauma was assessed with the Childhood Trauma Questionnaire, self-report version.

RESULTS

Patients from ethnic minority groups (n = 69) reported significantly more childhood trauma, specifically physical abuse/neglect, and sexual abuse. They had significantly more current hallucinatory behaviour and lifetime symptoms of hearing two or more voices conversing. Regression analyses revealed that the presence of childhood trauma mediated the association between ethnic minorities and hallucinations.

CONCLUSIONS

More childhood trauma in ethnic minorities with psychosis may partially explain findings of more positive symptoms, especially hallucinations, in this group. The association between childhood trauma and these first-rank symptoms may in part explain this group's higher risk of being diagnosed with a schizophrenia-spectrum diagnosis. The findings show the importance of childhood trauma in symptom development in psychosis.

Migration, ethnicity, and psychosis: toward a sociodevelopmental model

There is consistent and strong evidence that the incidence of all psychoses is higher in many migrant and minority ethnic populations in a number of countries. The reasons for this are, however, unclear and a wide range of explanations have been proposed, from genetic to neurodevelopmental to psychosocial. In this article, we describe and evaluate the available evidence for and against each of these. What this shows is that: (1) there are few studies that have directly investigated specific risk factors in migrant and minority ethnic populations, with often only 1 or 2 studies of any relevance to specific explanations and (2) what limited research there has been tends to implicate a diverse range of social factors (including childhood separation from parents, discrimination and, at an area level, ethnic density) as being of potential importance. In an attempt to synthesize these disparate findings and provide a basis for future research, we go on to propose an integrated model--of a sociodevelopmental pathway to psychosis--to account for the reported high rates in migrant and minority ethnic populations. Aspects of this model will be directly tested in a new Europe-wide incidence and case-control study that we will conduct over the next 3 years, as part of the European Network of National Schizophrenia Networks studying Gene-Environment Interactions programme.