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Background. Familial liability to both severe and common mental disorder predicts psychotic disorder and psychotic symptoms, and may be used as a proxy in models examining interaction between genetic risk and the environment at individual and contextual levels. Method. In a representative general population sample (n = 4011) in Izmir, Turkey, the full spectrum of expression of psychosis representing (0) no symptoms, (1) subclinical psychotic experiences, (2) low-impact psychotic symptoms, (3) high-impact psychotic symptoms and (4) full-blown clinical psychotic disorder was assessed in relation to mental health problems in the family (proxy for familial liability) and the wider social environment. Quality of the wider social environment was assessed in an independent sample using contextual measures of informal social control, social disorganization, unemployment and low income, aggregated to the neighbourhood level. Results. The association between familial liability to severe mental illness and expression of psychosis spectrum was stronger in more deprived neighbourhoods [e.g. this association increased from β=0.33 (p=0.01) in low-unemployment neighbourhoods to β=0.92 (p<0.001) in high-unemployment neighbourhoods] and in neighbourhoods high in social control, while neighbourhood variables did not modify the association between familial liability to common mental disorder and the psychosis outcome. Neighbourhood variables mediated urbanicity effects. Conclusions. Contextual effects may be important in moderating the expression of psychosis liability in populations, representing a specific pathway independent of the link between common mental disorder and psychosis. [ABSTRACT FROM AUTHOR]

Background: Psychotic experiences (PEs) may predict a range of common, non-psychotic disorders as well as psychotic disorders. In this representative, general population-based cohort study, both psychotic and non-psychotic disorder outcomes of PE were analysed, as were potential moderators., Methods: Addresses were contacted in a multistage clustered probability sampling frame covering 11 districts and 302 neighbourhoods at baseline (n = 4011). Participants were interviewed with the Composite International Diagnostic Interview (CIDI) both at baseline and at 6-year follow-up. Participants with PE at baseline were clinically re-interviewed with the SCID-I at follow-up. The role of socio-demographics, characteristics of PE, co-occurrence of mood disorders and family history of mental disorders were tested in the association between baseline PE and follow-up diagnosis., Results: In the participants with baseline PE, the psychotic disorder diagnosis rate at follow up was 7.0% - much lower than the rates of DSM-IV mood disorders without psychotic features (42.8%) and other non-psychotic disorders (24.1%). Within the group with baseline PE, female sex, lower socio-economic status, co-occurrence of mood disorders, family history of a mental disorder and persistence of PE predicted any follow-up DSM diagnosis. Furthermore, onset of psychotic v. non-psychotic disorder was predicted by younger age (15-30 years), co-presence of delusional and hallucinatory PE and family history of severe mental illness., Conclusion: The outcome of PE appears to be a consequence of baseline severity of multidimensional psychopathology and familial risk. It may be useful to consider PE as a risk indicator that has trans-diagnostic value.

A growing number of studies demonstrate high rates of subthreshold psychotic experiences, but there is considerable heterogeneity in rates due to study cohort and design factors, obscuring how prevalent psychotic experiences may or may not relate to rare psychotic disorders. In a representative general population sample (n = 4011) in Izmir, Turkey, the full spectrum of expression of psychosis was categorized across 5 groups representing (1) absence of psychosis, (2) subclinical psychotic experiences, (3) low-impact psychotic symptoms, (4) high-impact psychotic symptoms, and (5) full-blown clinical psychotic disorder and analyzed for continuity and discontinuity in relation to (1) other symptom dimensions associated with psychotic disorder and (2) proxies of genetic and nongenetic etiology. Results were tested for linear and extralinear contrasts between clinical and nonclinical and between disorder and nondisorder expression of psychosis. Demographic variables, indexing premorbid social adjustment and socioeconomic status, impacted mostly linearly; proxy variables of genetic loading (more or more severely affected relatives) impacted in a positive extralinear fashion; environmental risk factors sometimes impacted linearly (urbanicity and childhood adversity) and sometimes extralinearly (cannabis), occasioning a disproportional shift in risk at the clinical disorder end of the spectrum. Affective symptoms were associated with a disproportionally higher risk below the disorder threshold, whereas a disproportionally higher risk above the threshold was associated with psychotic symptom load, negative symptoms, disorganization, and visible signs of mental illness. Liability associated with respectively affective and nonaffective symptom domains, in interaction with environmental risks, may operate by impacting differentially over a quasi-continuous extended psychosis phenotype in the population.

Purpose: While there are consistent reports of a high psychosis rate among certain groups of migrants in Europe, there is little information on their risk for mood disorders. The aim of this study was to investigate the risk of receiving psychiatric treatment for mood disorders or psychotic disorders, comparing migrants and Dutch nationals in an ethnically mixed catchment area. A second aim was to calculate the 1-year prevalence rates of psychotic disorders in first-generation migrants., Method: A psychiatric registry provided information on treatments at all in- and outpatient facilities. Statistics Netherlands provided annual population figures., Results: The risk of receiving treatment for unipolar depressive disorder was increased for the Turkish-Dutch (first and second generation combined; age- and sex-adjusted relative risk 4.9; 95% CI: 4.4-5.5), Moroccan-Dutch (RR = 3.6; 3.3-4.0) and Surinamese-Dutch (RR=1.8; 1.5-2.2). The risk of being treated for bipolar disorder was not significantly increased for any group, except for the Turkish-Dutch of the second generation. The risk of treatment for non-affective psychotic disorder was very high for the Turkish-Dutch, Moroccan-Dutch and Surinamese-Dutch of the second generation. There was a large difference in the relative risk of this disorder between the Turkish-Dutch of the first (RR = 1.3; 1.0-1.8) and the second generation (RR = 8.7; 5.5-13.9). The 1-year prevalence rates of treated psychotic disorders were highest for Surinamese-Dutch (2.1%) and Moroccan-Dutch males (1.2%) of the first generation. Migrants from western-European countries were not at increased risk for any of these disorders., Conclusions: The stressful position of non-Western migrants in Dutch society has negative consequences on their mental health.

Objective: To describe the objectives and design of a multistage study on the prevalence and risk factors of mental health problems, in particular psychotic disorders and psychotic symptoms, by assessing a probabilistic sample of household residents in the Izmir Metropolitan Area, aged 15-64 years., Method: The study included three different observation frames. In the first stage, of which methodology is in the focus of this paper, the primary screening instrument was the Composite International Diagnostic Interview 2.1, which assesses lifetime and/or last one year occurrence of several DSM-IV disorders. Second, a parallel survey of social capital of administrative wards was conducted in the same neighbourhoods. Third, a nested-case control study was performed to study effects of genetic and environmental risk factors on wide psychosis phenotype., Results: A total of 4011 males and females were contacted through a multistage clustered area probability sample of administrative neighbourhoods and households, covering 9 districts and 302 neighbourhoods. The response rate for the first stage was 76.5% in 5242 eligible households. Respondents were interviewed at home in 2008 for the screening of included mental health problems. The screened disorders were mood disorders (last 1 year), schizophrenia and other non-affective psychotic disorders (lifetime), and dependence and abuse of psychoactive substances (lifetime)., Conclusion: Although cross-sectional in nature, the TürkSch has a unique study design and yields data of high quality. This enables study of the prevalence, risk and higher-order interactions underlying ill-health in the Turkish population, with a specific focus on psychosis.

Background: Cannabis use may be a risk factor for schizophrenia. Part of this association may be explained by genotype-environment interaction, and part of it by genotype-environment correlation. The latter issue has not been explored. We investigated whether cannabis use is associated with schizophrenia, and whether gene-environment correlation contributes to this association, by examining the prevalence of cannabis use in groups with different levels of genetic predisposition for schizophrenia., Method: Case-control study of first-episode schizophrenia. Cases included all non-Western immigrants who made first contact with a physician for schizophrenia in The Hague, The Netherlands, between October 2000 and July 2005 (n=100; highest genetic predisposition). Two matched control groups were recruited, one among siblings of the cases (n=63; intermediate genetic predisposition) and one among immigrants who made contact with non-psychiatric secondary health-care services (n=100; lowest genetic predisposition). Conditional logistic regression analyses were used to predict schizophrenia as a function of cannabis use, and cannabis use as a function of genetic predisposition for schizophrenia., Results: Cases had used cannabis significantly more often than their siblings and general hospital controls (59, 21 and 21% respectively). Cannabis use predicted schizophrenia [adjusted odds ratio (OR) cases compared to general hospital controls 7.8, 95% confidence interval (CI) 2.7-22.6; adjusted OR cases compared to siblings 15.9 (95% CI 1.5-167.1)], but genetic predisposition for schizophrenia did not predict cannabis use [adjusted OR intermediate predisposition compared to lowest predisposition 1.2 (95% CI 0.4-3.8)]., Conclusions: Cannabis use was associated with schizophrenia but there was no evidence for genotype-environment correlation.

Objective: A high incidence of psychotic disorders has been reported in immigrant ethnic groups in Western Europe. Some studies suggest that ethnic density may influence the incidence of schizophrenia. The authors investigated whether this increased incidence among immigrants depends on the ethnic density of the neighborhoods in which they live., Method: This was a prospective first-contact incidence study of psychotic disorders in The Hague, by ethnicity and neighborhood of residence. Over a 7-year period, individuals who made contact with a physician for a suspected psychotic disorder underwent diagnostic interviews and received DSM-IV diagnoses. A comprehensive municipal registration system provided the denominator for incidence rates. Data were sufficient to examine incidence rates in native Dutch and in first- and second-generation immigrants from Morocco, Suriname, and Turkey. The ethnic density of a neighborhood was computed for each immigrant group as the proportion of residents belonging to that group. Multilevel regression analyses predicted the incidence of psychotic disorders as a function of individual ethnicity and neighborhood ethnic density. Models were fitted for all immigrants together and for each immigrant group separately., Results: A total of 226 native Dutch and 240 immigrants were diagnosed as having a psychotic disorder. Compared with native Dutch, the adjusted incidence rate ratio for immigrants was significantly increased in low-ethnic-density neighborhoods (2.36) but not in high-ethnic-density neighborhoods (1.25). There was a strong interaction between individual ethnicity and neighborhood ethnic density as predictors of incidence of illness. These findings were consistent across all immigrant groups., Conclusions: The incidence of psychotic disorders was elevated most significantly among immigrants living in neighborhoods where their own ethnic group comprised a small proportion of the population.