Wim Veling

Incidence of schizophrenia among ethnic minorities in the Netherlands : A four-year first-contact study

There is only one previous report on the first-contact incidence of schizophrenia among immigrants in the Netherlands, which was based on a small number of cases, particularly for second generation immigrants. We conducted another two-year first-contact incidence study in the same geographical area, combined the data of both studies and compared risks over all four years. The incidence of schizophrenia was increased for all first generation non-Western immigrants. The risk was particularly high for second generation immigrants: the age- and gender-adjusted incidence rate ratio was 5.8 (95% CI, 2.9-11.4) for Moroccans, 2.9 (1.6-5.0) for Surinamese, 2.3 (1.0-5.4) for Turks, and 3.5 (1.8-6.8) for immigrants from other non-Western countries.

The Validity of the 16-Item Version of the Prodromal Questionnaire (PQ-16) to Screen for Ultra High Risk of Developing Psychosis in the General Help-Seeking Population

In order to bring about implementation of routine screening for psychosis risk, a brief version of the Prodromal Questionnaire (PQ; Loewy et al., 2005) was developed and tested in a general help-seeking population. We assessed a consecutive patient sample of 3533 young adults who were help-seeking for nonpsychotic disorders at the secondary mental health services in The Hague with the PQ. We performed logistic regression analyses and CHi-squared Automatic Interaction Detector decision tree analysis to shorten the original 92 items. Receiver operating characteristic curves were used to examine the psychometric properties of the PQ-16. In the general help-seeking population, a cutoff score of 6 or more positively answered items on the 16-item version of the PQ produced correct classification of Comprehensive Assessment of At-Risk Mental State (Yung et al., 2005) psychosis risk/clinical psychosis in 44% of the cases, distinguishing Comprehensive Assessment of At-Risk Mental States (CAARMS) diagnosis from no CAARMS diagnosis with high sensitivity (87%) and specificity (87%). These results were comparable to the PQ-92. The PQ-16 is a good self-report screen for use in secondary mental health care services to select subjects for interviewing for psychosis risk. The low number of items makes it quite appropriate for screening large help-seeking populations, thus enhancing the feasibility of detection and treatment of ultra high-risk patients in routine mental health services.

Age at Migration and Future Risk of Psychotic Disorders Among Immigrants in the Netherlands: A 7-Year Incidence Study

OBJECTIVE The purpose of this study was to examine whether the increased risk for developing a psychotic disorder among immigrants is related to their age at the time of migration. METHOD In a 7-year first-contact incidence study, immigrants to the Netherlands and Dutch citizens, ages 15-54 years, who made a first contact with a physician for a suspected psychotic disorder were identified. Diagnostic interviews were administered, and DSM-IV diagnoses were determined by consensus between two psychiatrists. A comprehensive municipal registration system provided the denominator, including information on ethnicity and age at the time of migration. RESULTS Lower age at the time of migration was associated with a higher incidence of psychotic disorders among immigrants. People who migrated between the ages of 0 and 4 years had the most elevated risk for psychotic disorders compared with the risk among Dutch citizens (age- and sex-adjusted incidence rate ratio=2.96, 95% confidence interval [CI]=2.10-4.17), and the risk gradually decreased with older age at migration (adjusted incidence rate ratio for migration at 5-9 years, 10-14 years, and >29 years, respectively: 2.31 [CI=1.61-3.29], 1.51 [CI=1.02-2.25], and 1.00 [CI=0.58-1.72]). CONCLUSIONS The adverse influence of migration on the risk for psychotic disorders is most prominent in early life, suggesting that this is an important period in the etiology of the illness.

Ethnic minority position and risk for psychotic disorders

Purpose of review This article reviews the recent literature about migration, ethnic minority position and the risk of psychotic disorders. Recent findings A meta-analysis found that both first and second-generation migrants have on average a two-fold increase in risk for psychotic disorders. In the Netherlands, the risk was most elevated for individuals who migrated in early childhood. Several studies investigated diagnostic ethnic bias and reported greater likelihood of schizophrenia diagnosis in ethnic minority patients at the cost of diagnosis of affective psychotic disorders. Neighbourhood ethnic density was related to prevalence of psychotic experiences in ethnic minority populations in the UK. Perceived discrimination was associated with severity of psychotic and depressive symptoms in ethnic minority patients. Both weak and strong ethnic identification, as well as experiences of social adversity, were related to risk for psychosis. Low neonatal vitamin D was associated with adult risk for psychosis and vitamin D levels in childhood were associated with nonclinical psychotic experiences. Summary The risk for psychotic disorders is increased among ethnic minority populations. Experiences of social adversity and having a disadvantaged outsider status may explain the excess risk. More research is needed into potential biological mechanisms, including vitamin D.

Cannabis use and genetic predisposition for schizophrenia: a case-control study.

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.

The Validity and Utility of Subtyping Bulimia Nervosa

OBJECTIVE To review the evidence for the validity and utility of subtyping bulimia nervosa (BN) into a purging (BN-P) and a nonpurging subtype (BN-NP), and of distinguishing BN-NP from binge eating disorder (BED), by comparing course, complications, and treatment. METHOD A literature search of psychiatry databases for studies published in peer-reviewed journals that used the DSM-definitions of BN and BED, and included both individuals with BN-NP and individuals with BN-P and/or BED. RESULTS Twenty-three studies compared individuals with BN-NP (N = 671) to individuals with BN-P (N = 1795) and/or individuals with BED (N = 1921), two of which reported on course, 12 on comorbidity and none on treatment response-the indicators for validity and clinical utility. The differences found were mainly quantitative rather than qualitative, suggesting a gradual difference in severity from BN-P (most severe) through BN-NP to BED (least severe). DISCUSSION None of the comparisons provided convincing evidence for the validity or utility of the BN-NP diagnosis. Three options for the position of BN-NP in DSM-V were suggested: (1) maintaining the BN-NP subtype, (2) dropping nonpurging compensatory behavior as a criterion for BN, so that individuals currently designated as having BN-NP would be designated as having BED, and (3) including BN-NP in a broad BN category.

Sexual minority status and psychotic symptoms: findings from the Netherlands Mental Health Survey and Incidence Studies (NEMESIS)

BACKGROUND Ethnic minority position is associated with increased risk for psychotic outcomes, which may be mediated by experiences of social exclusion, defeat and discrimination. Sexual minorities are subject to similar stressors. The aim of this study is to examine whether sexual minorities are at increased risk for psychotic symptoms and to explore mediating pathways. METHOD A cross-sectional survey was performed assessing cumulative incidence of psychotic symptoms with the Composite International Diagnostic Interview in two separate random general population samples (NEMESIS-1 and NEMESIS-2). Participants were sexually active and aged 18-64 years (n = 5927, n = 5308). Being lesbian, gay or bisexual (LGB) was defined as having sexual relations with at least one same-sex partner during the past year. Lifetime experience of any psychotic symptom was analysed using logistic regression, adjusted for gender, educational level, urbanicity, foreign-born parents, living without a partner, cannabis use and other drug use. RESULTS The rate of any psychotic symptom was elevated in the LGB population as compared with the heterosexual population both in NEMESIS-1 [odds ratio (OR) 2.56, 95% confidence interval (CI) 1.71-3.84] and NEMESIS-2 (OR 2.30, 95% CI 1.42-3.71). Childhood trauma, bullying and experience of discrimination partly mediated the association. CONCLUSIONS The finding that LGB orientation is associated with psychotic symptoms adds to the growing body of literature linking minority status with psychosis and other mental health problems, and suggests that exposure to minority stress represents an important mechanism.

Migration and psychotic disorders.

The incidence of psychotic disorders is extremely high in several immigrant groups in Europe. This article describes the epidemiological evidence for increased incidence rates among immigrants compared with nonimmigrant populations and explores possible explanations for this excess risk. Potential causes not only involve factors acting at the level of the individual, but encompass the broader social context of neighborhoods and ethnic groups. Growing up and living in a disadvantaged ethnic minority position, characterized by a low social status, high degree of discrimination against the group and low neighborhood ethnic density, may lead to an increased risk of psychotic disorders, especially when individuals reject their minority status and when their social resources are insufficient to buffer the impact of adverse social experiences. Future research should refine measures of the social context, adopt a life-course perspective and should integrate social and neurobiological pathways.

Environmental Social Stress, Paranoia and Psychosis Liability: A Virtual Reality Study

The impact of social environments on mental states is difficult to assess, limiting the understanding of which aspects of the social environment contribute to the onset of psychotic symptoms and how individual characteristics moderate this outcome. This study aimed to test sensitivity to environmental social stress as a mechanism of psychosis using Virtual Reality (VR) experiments. Fifty-five patients with recent onset psychotic disorder, 20 patients at ultra high risk for psychosis, 42 siblings of patients with psychosis, and 53 controls walked 5 times in a virtual bar with different levels of environmental social stress. Virtual social stressors were population density, ethnic density and hostility. Paranoia about virtual humans and subjective distress in response to virtual social stress exposures were measured with State Social Paranoia Scale (SSPS) and self-rated momentary subjective distress (SUD), respectively. Pre-existing (subclinical) symptoms were assessed with the Community Assessment of Psychic Experiences (CAPE), Green Paranoid Thoughts Scale (GPTS) and the Social Interaction Anxiety Scale (SIAS). Paranoia and subjective distress increased with degree of social stress in the environment. Psychosis liability and pre-existing symptoms, in particular negative affect, positively impacted the level of paranoia and distress in response to social stress. These results provide experimental evidence that heightened sensitivity to environmental social stress may play an important role in the onset and course of psychosis.

Virtual reality experiments linking social environment and psychosis: A pilot study

Initial studies with healthy subjects and individuals with high risk for psychosis have suggested that virtual reality (VR) environments may be used to investigate social and psychological mechanisms of psychosis. One small study reported that VR can safely be used in individuals with current persecutory delusions. The present pilot study investigated the feasibility and potential negative side effects of exposure to different virtual social risk environments in patients with first episode psychosis and in healthy controls. Seventeen patients with first episode psychosis (FEP) and 24 healthy control subjects (HC) participated in four virtual experiments during which they walked for 3.5-4 minutes in a virtual café, looking for avatars with digits on their clothing. The level of paranoid thoughts, as well as psychological, physiological, and behavioral correlates of paranoid thoughts, were measured in different virtual social risk environments, manipulating two factors: population density and ethnicity of avatars. FEP and HC frequently had paranoid thoughts about avatars. Paranoia in the real world correlated strongly with paranoid thoughts about avatars in virtual environments (Spearmans ρ=0.67 and 0.54 in FEP and HC respectively, p<0.01). FEP kept a smaller distance to avatars than HC. In FEP, but not in HC, galvanic skin response was significantly stronger in virtual environments with avatars of other ethnicity than in the own ethnicity condition. These results suggest that VR is an acceptable and sufficiently realistic method to use in patients with first episode psychosis. VR research may help to increase our understanding of the social and psychological mechanisms of psychosis and to develop new treatment applications.