The contribution of cannabis use to the increased psychosis risk among minority ethnic groups in Europe.

BACKGROUND: We examined whether cannabis use contributes to the increased risk of psychotic disorder for non-western minorities in Europe. METHODS: We used data from the EU-GEI study (collected at sites in Spain, Italy, France, the United Kingdom, and the Netherlands) on 825 first-episode patients and 1026 controls. We estimated the odds ratio (OR) of psychotic disorder for several groups of migrants compared with the local reference population, without and with adjustment for measures of cannabis use. RESULTS: The OR of psychotic disorder for non-western minorities, adjusted for age, sex, and recruitment area, was 1.80 (95% CI 1.39-2.33). Further adjustment of this OR for frequency of cannabis use had a minimal effect: OR = 1.81 (95% CI 1.38-2.37). The same applied to adjustment for frequency of use of high-potency cannabis. Likewise, adjustments of ORs for most sub-groups of non-western countries had a minimal effect. There were two exceptions. For the Black Caribbean group in London, after adjustment for frequency of use of high-potency cannabis the OR decreased from 2.45 (95% CI 1.25-4.79) to 1.61 (95% CI 0.74-3.51). Similarly, the OR for Surinamese and Dutch Antillean individuals in Amsterdam decreased after adjustment for daily use: from 2.57 (95% CI 1.07-6.15) to 1.67 (95% CI 0.62-4.53). CONCLUSIONS: The contribution of cannabis use to the excess risk of psychotic disorder for non-western minorities was small. However, some evidence of an effect was found for people of Black Caribbean heritage in London and for those of Surinamese and Dutch Antillean heritage in Amsterdam.

[Linguistic distance and psychosis in ethnic minorities]. / Taalachterstand en psychose onder mensen met een migratieachtergrond.

BACKGROUND: Ethnic minorities in the Netherlands face an excess psychosis risk, and understanding of causality remains limited. Linguistic disadvantage and other indicators of societal exclusion might play a role, and offer potential targets for public health interventions. AIM: To establish the contribution of linguistic disadvantage, indicators of social distance and perceived discrimination to the increased risk of psychoses in migrants and ethnic minorities. METHODS: We used the Dutch data from an international case-control study into psychotic disorders (the EU-GEI study). A first episode of psychosis was our outcome variable, and we used well-defined data on established confounders (e.g. age and sex) and indicators of ethnicity, social distance, linguistic disadvantage and perceived discrimination as our predictor variables. RESULTS: Ethnic minorities face an increased psychosis risk. This appears to be the case for both first- and second- generation migrants and so-called ‘Western’ and non-Western migrants. Though confounders and social distance appear to contribute, linguistic disadvantage appears to play a role in the excess psychosis risk in first-generation migrants. CONCLUSION: Reducing the social consequences of linguistic disadvantage or social distance might be a starting point for concrete public health interventions aimed at preventing the increased psychosis risk faced by first-generation migrants.

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.

Testing Ødegaard's selective migration hypothesis: a longitudinal cohort study of risk factors for non-affective psychotic disorders among prospective emigrants.

BACKGROUND: The selection hypothesis posits that the increased rates of psychosis observed among migrants are due to selective migration of people who are predisposed to develop the disorder. To test this hypothesis, we examined whether risk factors for psychosis are more prevalent among future emigrants. METHOD: A cohort of 49,321 Swedish military conscripts was assessed at age 18 years on cannabis use, IQ, psychiatric diagnosis, social adjustment, history of trauma and urbanicity of place of upbringing. Through data linkage we examined whether these exposures predicted emigration out of Sweden. We also calculated the emigrants' hypothetical relative risk compared with non-emigrants for developing a non-affective psychotic disorder. RESULTS: Low IQ [odds ratio (OR) 0.5, 95% confidence interval (95% CI) 0.3-0.9] and 'poor social adjustment' (OR 0.4, 95% CI 0.2-0.8) were significantly less prevalent among prospective emigrants, whereas a history of urban upbringing (OR 2.3, 95% CI 1.4-3.7) was significantly more common. Apart from a non-significant increase in cannabis use among emigrants (OR 1.6, 95% CI 0.8-3.1), there were no major group differences in any other risk factors. Compared to non-emigrants, hypothetical relative risks for developing non-affective psychotic disorder were 0.7 (95% CI 0.4-1.2) and 0.8 (95% CI 0.7-1.0), respectively, for emigrants narrowly and broadly defined. CONCLUSIONS: This study adds to an increasing body of evidence opposing the selection hypothesis.

An incidence study of diagnosed autism-spectrum disorders among immigrants to the Netherlands.

OBJECTIVE: To estimate the risk of developing autism-spectrum disorder (ASD) in children born to immigrants as compared with children of Dutch-born parents. METHOD: Retrospective, population-based cohort study of all live births (n = 106 953) between 1998 and 2007 in a circumscribed geographical region in the Netherlands. Cohort members were linked to the Psychiatric Case Register to identify diagnosed cases. RESULTS: A total of 518 cases of ASD were identified, including 150 children with autism and 368 children with Asperger syndrome or Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS). Children born to migrants from developing countries were at significantly lower risk of ASD [rate ratio (RR) = 0.6, 95% confidence interval (CI) 0.5-0.9] than children of Dutch-born parents. Within the ASD group, the risk for the subgroup with Asperger syndrome and PDD-NOS was reduced (RR = 0.4, 95% CI 0.3-0.6), whereas that for narrowly defined autism was non-significantly increased (RR = 1.4, 95% CI 0.9-2.4). Migrant groups did not differ in age at diagnosis. CONCLUSION: The results echo Swedish findings indicating a reversal of risk gradient in children of parents from developing countries, specifically a decreased risk for high-functioning and increased risk for low-functioning autism.

Childhood bullying and the association with psychosis in non-clinical and clinical samples: a review and meta-analysis.

BACKGROUND: Approximately 11% of schoolchildren are bullied on a regular basis. It has been argued that continuous exposure to stress is related to the development of psychotic symptoms. The current study sought to investigate whether being bullied in childhood is related to the development of psychotic symptoms. METHOD: A search of PubMed, PsycINFO and EMBASE was conducted. The reference lists of included papers were searched to identify other eligible papers. A meta-analysis was performed on a subgroup of studies. RESULTS: We found four clinical and 10 general population studies that met inclusion criteria. The results of the clinical studies were mixed. However, the results of the non-clinical studies provided more consistent evidence that school bullying is related to the development of non-clinical psychotic symptoms. Stronger associations were found with increased frequency and severity and longer duration of being bullied. We performed a meta-analysis on seven population-based studies, yielding unadjusted and adjusted odds ratios (ORs) of 2.7 [95% confidence interval (CI) 2.1-3.6] and 2.3 (95% CI 1.5-3.4) respectively. CONCLUSIONS: Although there is some evidence of an association between bullying and psychosis in clinical samples, the research is too sparse to draw any firm conclusions. However, population-based non-clinical studies support the role of bullying in the development of psychotic symptoms later in life. These findings are consistent with findings of an increased risk of psychotic symptoms among those exposed to other types of abuse.

A meta-analysis of the risk for psychotic disorders among first- and second-generation immigrants.

BACKGROUND: There is increasing acceptance of migration as a risk factor for schizophrenia and related disorders; however, the magnitude of the risk among second-generation immigrants (SGIs) remains unclear. Generational differences in the incidence of psychotic disorders among migrants might improve our understanding of the relationship between migration, ethnicity and psychotic disorders. This meta-analysis aimed at determining the risk of psychotic disorders among SGIs in comparison with non-migrants and first-generation immigrants (FGIs). METHOD: Medline, EMBASE and PsycINFO databases were searched systematically for population-based studies on migration and psychotic disorders published between 1977 and 2008. We also contacted experts, tracked citations and screened bibliographies. All potential publications were screened by two independent reviewers in a threefold process. Studies were included in the meta-analysis if they reported incidence data, differentiated FGIs from SGIs and provided age-adjusted data. Data extraction and quality assessment were conducted for each study. RESULTS: Twenty-one studies met all inclusion criteria. A meta-analysis of 61 effect sizes for FGIs and 28 for SGIs yielded mean-weighted incidence rate ratios (IRRs) of 2.3 [95% confidence interval (CI) 2.0-2.7] for FGIs and 2.1 (95% CI 1.8-2.5) for SGIs. There was no significant risk difference between generations, but there were significant differences according to ethno-racial status and host country. CONCLUSIONS: The increased risk of schizophrenia and related disorders among immigrants clearly persists into the second generation, suggesting that post-migration factors play a more important role than pre-migration factors or migration per se. The observed variability suggests that the risk is mediated by the social context.

Food intake and socioeconomic status in children in northeast Thailand.

To assess the food intake and to evaluate the relationship between socioeconomic status (SES) and food consumption of northeastern Thai children a dietary survey was carried out among 108 urban and rural 3-8-year-olds in Sakon Nakhon province. Energy and nutrient intakes were assessed by the 24 hour recall method and calculated with local food consumption tables. Urban children consumed significantly more eggs and products containing animal proteins than rural children. In urban areas the percentage of users of meat, eggs, and fruit was significantly higher than in rural areas; fish was consumed more frequently in rural areas. As compared with the FAO/WHO RDA (Recommended Daily Allowances) all children showed a very inadequate supply of energy, calcium, iron (except urban children), vitamin A, thiamin, riboflavin, and niacin. The mean daily protein intake was almost equal to or higher than the calculated requirements. Children of lower socioeconomic background showed a lower fat intake, a lower contribution of fat to the energy intake, and a higher contribution of carbohydrates to the energy intake than children from families with a higher SES. This study shows that nutrient intakes far below recommended intakes are common among the examined northeastern Thai children and of a serious nature, and that much more emphasis needs to be given to increase the energy or food intake rather than the protein content of their grossly inadequate diets.