Does urbanicity shift the population expression of psychosis?

Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, P.O. Box 616 (DRT 10), 6200 MD Maastricht, The Netherlands.
Journal of Psychiatric Research (Impact Factor: 3.96). 11/2004; 38(6):613-8. DOI: 10.1016/j.jpsychires.2004.04.003
Source: PubMed


Growing up in an urban area has been shown to be associated with an increased risk of psychotic disorder in later life. While it is commonly held that a only a tiny fraction of exposed individuals will develop schizophrenia, recent evidence suggests that expression of psychosis in exposed individuals may be much more common, albeit at attenuated levels. Findings are based on a population sample of 2548 adolescents and young adults aged originally 14-24 years, and followed up over almost 5 years up to ages 17-28 years. Trained psychologists assessed all these subjects with the core psychosis sections on delusions and hallucinations of the Munich-Composite International Diagnostic Interview. Growing up in an urban area was associated with an increased risk of expression of psychosis in the adolescents and young adults (adjusted OR 1.31, 95% CI 1.03-1.66). The proxy environmental risk factor that urbanicity represents may shift a relatively large section of the adolescent population along a continuum of expression of psychosis. Other causal influences may be required to make the transition to schizophrenia in adult life.

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    • "Consistent with previous work (Spauwen et al. 2004; Wigman et al. 2012), urbanicity was defined as living, at baseline, in the urban region of the German city of Munich versus the surrounding areas of Munich. The urban area, hence defined, had a population density of 4061 persons per square mile; for the rural area, this was 553 persons per square mile. "
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    ABSTRACT: Evidence suggests that in affective, non-psychotic disorders: (i) environmental exposures increase risk of subthreshold psychotic experiences (PEs) and strengthen connectivity between domains of affective and subthreshold psychotic psychopathology; and (ii) PEs are a marker of illness severity. In 3021 adolescents from the Early Developmental Stages of Psychopathology cohort, we tested whether the association between PEs and presence of DSM-IV mood disorder (MD)/obsessive-compulsive disorder (OCD) would be moderated by risk factors for psychosis (cannabis use, childhood trauma and urbanicity), using the interaction contrast ratio (ICR) method. Furthermore, we analysed whether the interaction between environment and PEs was mediated by non-psychotic psychopathology. The association between PEs and MD/OCD was moderated by urbanicity (ICR = 2.46, p = 0.005), cannabis use (ICR = 3.76, p = 0.010) and, suggestively, trauma (ICR = 1.91, p = 0.063). Exposure to more than one environmental risk factor increased the likelihood of co-expression of PEs in a dose-response fashion. Moderating effects of environmental exposures were largely mediated by the severity of general non-psychotic psychopathology (percentage explained 56-68%, all p < 0.001). Within individuals with MD/OCD, the association between PEs and help-seeking behaviour, as an index of severity, was moderated by trauma (ICR = 1.87, p = 0.009) and urbanicity (ICR = 1.48, p = 0.005), but not by cannabis use. In non-psychotic disorder, environmental factors increase the likelihood of psychosis admixture and help-seeking behaviour through an increase in general psychopathology. The findings are compatible with a relational model of psychopathology in which more severe clinical states are the result of environment-induced disturbances spreading through a psychopathology network.
    Psychological Medicine 03/2015; 45(11):1-13. DOI:10.1017/S0033291715000380 · 5.94 Impact Factor
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    • "An important observation is that studies have demonstrated that the generally good (because the symptoms are only transitory as described above) outcome of subclinical psychotic experiences can be modified to poorer outcomes of persistence and clinical need for care if subjects are exposed to additional (proxy) environmental risk factors. Examples of these are trauma (Spauwen et al. 2006b), cannabis (Henquet et al. 2005) and urbanicity (Spauwen et al. 2004, 2006a). This fact, together with the above discussed findings of a high prevalence of psychotic experiences, their familial clustering, age-associated expression and low rate of transition to psychotic disorder, suggests a model of psychosis that considers genetic background factors impacting on a broadly distributed and transitory population expression of psychosis during development, the poor prognosis of which, in terms of persistence and clinical need, is predicted by environmental exposures interacting with genetic risk. "
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    ABSTRACT: A systematic review of all reported incidence and prevalence studies of population rates of subclinical psychotic experiences reveals a median prevalence rate of around 5% and a median incidence rate of around 3%. A meta-analysis of risk factors reveals associations with developmental stage, child and adult social adversity, psychoactive drug use, and also male sex and migrant status. The small difference between prevalence and incidence rates, together with data from follow-up studies, indicates that approximately 75-90% of developmental psychotic experiences are transitory and disappear over time. There is evidence, however, that transitory developmental expression of psychosis (psychosis proneness) may become abnormally persistent (persistence) and subsequently clinically relevant (impairment), depending on the degree of environmental risk the person is additionally exposed to. The psychosis proneness-persistence-impairment model considers genetic background factors impacting on a broadly distributed and transitory population expression of psychosis during development, poor prognosis of which, in terms of persistence and clinical need, is predicted by environmental exposure interacting with genetic risk.
    Psychological Medicine 08/2008; 39(2):179-95. DOI:10.1017/S0033291708003814 · 5.94 Impact Factor
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    • "Their effects are small and many may be involved. They are likely to interact with environmental exposures that impact on the individual over the life course, such as fetal hypoxia (Cannon et al., 2002), the proxy environmental risk factor: season of birth (Mortensen et al., 1999), adverse rearing environments (Tienari et al., 2004), the stresses of urban life during upbringing (van Os et al., 2003, Spauwen et al., 2004), cannabis use (Verdoux et al., 2003), stress in daily life (Myin-Germeys et al., 2001) and a minority position (Hutchinson et al., 1996). The causes of schizophrenia impact on brain development, as evidenced by a small reduction in the volume of grey matter (Wright et al., 2000) that appears to progress over time, and may be linked to social deterioration, use of medication or factors intrinsic to the disease itself (Cahn et al., 2002, Ho et al., 2003a,b). "
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