Migration and schizophrenia

Department of Psychiatry, University Medical Centre, Utrecht, the Netherlands, and Department of Health Sciences, Lund University, Malmö University Hospital, Sweden.
Current Opinion in Psychiatry (Impact Factor: 3.94). 04/2007; 20(2):111-5. DOI: 10.1097/YCO.0b013e328017f68e
Source: PubMed


An exploration of the evidence that a history of migration is a risk factor for schizophrenia and an evaluation of those studies that seek an explanation for this.
A meta-analysis found an increased risk for schizophrenia among first-generation and second-generation migrants and found a particularly high risk for migrants from countries where the majority of the population was Black. The latter finding was confirmed and extended by a large first-contact incidence study in the UK, which found excessive risks for schizophrenia and mania in the African-Caribbean and black-African sections of the population. A very high risk of schizophrenia has also been reported for Moroccan males in the Netherlands. The explanation for these findings is uncertain. Social adversity, racial discrimination, family dysfunction, unemployment and poor housing conditions have been proposed as contributing factors. According to one hypothesis, the chronic experience of social defeat disturbs dopamine function in the brain.
A personal or family history of migration is a high risk factor for schizophrenia and there is now strong evidence against selective migration as the explanation. There is an increasing interest in the impact of social stressors on brain functioning and on the pathogenesis of schizophrenia.

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Available from: Jean-Paul Selten, Oct 04, 2015
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    • "Genome wide association studies and Linkage analyses have tried to identify susceptibility loci but, no common genetic variant confers in itself more than twice the risk in susceptibility for schizophrenia in general population [1]. Apart from genetic factors, several environmental factors have been implicated in the etiology of schizophrenia which includes migration [2], urbanicity during upbringing [3], prenatal famine [4], season of birth [5], Paternal age [6], in utero exposure to influenza epidemics [7], cannabis use [8] etc. Several studies have been done worldwide to elucidate the role of Gene X Environment interaction in vulnerability to schizophrenia [9]. "
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    ABSTRACT: DNA methylation has been implicated in the etiopathology of various complex disorders. DNA methyltransferases are involved in maintaining and establishing new methylation patterns. The aim of the present study was to investigate the inherent genetic variations within DNA methyltransferase genes in predisposing to susceptibility to schizophrenia. We screened for polymorphisms in DNA methyltransferases, DNMT1, DNMT3A, DNMT3B and DNMT3L in 330 schizophrenia patients and 302 healthy controls for association with Schizophrenia in south Indian population. These polymorphisms were also tested for subgroup analysis with patient's gender, age of onset and family history. DNMT1 rs2114724 (genotype P = .004, allele P = 0.022) and rs2228611 (genotype P = 0.004, allele P = 0.022) were found to be significantly associated at genotypic and allelic level with Schizophrenia in South Indian population. DNMT3B rs2424932 genotype (P = 0.023) and allele (P = 0.0063) increased the risk of developing schizophrenia in males but not in females. DNMT3B rs1569686 (genotype P = 0.027, allele P = 0.033) was found to be associated with early onset of schizophrenia and also with family history and early onset (genotype P = 0.009). DNMT3L rs2070565 (genotype P = 0.007, allele P = 0.0026) confers an increased risk of developing schizophrenia at an early age in individuals with family history. In-silico prediction indicated functional relevance of these SNPs in regulating the gene. These observations might be crucial in addressing and understanding the genetic control of methylation level differences from ethnic viewpoint. Functional significance of genotype variations within the DNMTs indeed suggest that the genetic nature of methyltransferases should be considered while addressing epigenetic events mediated by methylation in Schizophrenia.
    PLoS ONE 05/2014; 9(5):e98182. DOI:10.1371/journal.pone.0098182 · 3.23 Impact Factor
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    • "The association between immigration and psychosis has been firmly established through more than twenty international studies and two meta-analyses, with an estimated relative risk of 2.1 to 2.7 for firstgeneration immigrants relative to native-born populations (Cantor- Graae and Selten, 2005; Bourque et al., 2011). This appears to be driven by social factors rather than selective migration of people who have greater genetic risk (Selten et al., 2007). "
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    ABSTRACT: Previous studies have shown variation in the prevalence and incidence of psychosis across immigrant groups, but the underlying mechanisms are not fully understood. Stress related to acculturation may increase risk for psychosis among immigrant groups. In this study we examine the association between acculturative stress and psychotic-like experiences in a sample of Latino- and Asian-American immigrants to the United States in the National Latino and Asian American Study (n=2434). Acculturative stress was associated with visual and auditory hallucinations among Asians, but only with hearing voices among Latinos. Increased risk for psychotic-like experiences among Latinos was primarily associated with younger age of immigration. Acculturative stress appears to be a promising candidate mechanism explaining the relationship between immigration and psychosis, particularly among Asian Americans. Ethnic differences may reflect variability between groups that integrate more readily into the host culture and those that are subject to greater discrimination and environmental adversity.
    Schizophrenia Research 08/2013; 150(1). DOI:10.1016/j.schres.2013.07.040 · 3.92 Impact Factor
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    • "First, it has been suggested that misdiagnosis related to misinterpretations of cultural background could lead to an increase of the incidence of psychotic disorders because clinicians may fail to understand the cultural background of their patients. However, this hypothesis has not been confirmed and there is strong evidence against misdiagnosis as explanation for the increased incidence among migrants (Sharpley et al., 2001; Bhugra, 2004; Selten et al., 2007). Moreover, in our study, the diagnoses were validated by a senior psychiatrist who is familiar with transcultural psychiatry. "
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    ABSTRACT: There is very strong evidence that the prevalence of psychosis is elevated in migrant populations and that this risk persists into the second generation. However, these results have not been replicated in France, and the prevalence of psychotic disorders in the third generation of migrants remains unknown. Based on the Mental Health in General Population survey (n = 37 063), we report for the first time the increased prevalence of psychotic disorders in migrants in France, which persists into the second generation for a single psychotic ep-isode (SPE) (OR = 1.43, 95% CI [1.02–2.03], p b 0.03) and into the third generation for recurrent psychotic disorder (RPD) (OR = 1.78, 95% CI [1.45–2.18], p b 0.0001) after adjustment for age, sex, level of education and cannabis use. Complementary statistical analyses of our sample showed a significantly higher risk of SPE in migrants from the French West Indies and Africa (χ 2 = 17.70, p b 0.01). These results are consistent with the socio-developmental model and the psychosis continuum hypothesis.
    Schizophrenia Research 06/2013; DOI:10.1016/j.schres.2013.03.011 · 3.92 Impact Factor
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