Urbanicity, social adversity and psychosis

Abstract

In recent years, there has been increasing interest in research on geographical variation in the incidence of schizophrenia and other psychoses. In this paper, we review the evidence on variation in incidence of schizophrenia and other psychoses in terms of place, as well as the individual-and area-level factors that account for this variation. We further review findings on potential mechanisms that link adverse urban environment and psychosis. There is evidence from earlier and more recent studies that urbanicity is associated with an increased incidence of schizophrenia and non-affective psychosis. In addition, considerable variation in incidence across neighbourhoods has been observed for these disorders. Findings suggest it is unlikely that social drift alone can fully account for geographical variation in incidence. Evidence further suggests that the impact of adverse social contexts -indexed by area-level exposures such as population density, social fragmentation and deprivation -on risk of psychosis is explained (confounding) or modified (interaction) by environmental exposures at the individual level (i.e., cannabis use, social adversity, exclusion and discrimination). On a neurobiological level, several studies suggest a close link between social adversity, isolation and stress on the one hand, and monoamine dysfunction on the other, which resembles findings in schizophrenia patients. However, studies directly assessing correlations between urban stress or discrimination and neurobiological alterations in schizophrenia are lacking to date.Key words: Urbanicity, social adversity, psychosis, schizophrenia, social fragmentation, isolation, discrimination, stress (World Psychiatry 2013;12:187-197) In recent years, interest has been increasing in the role of the social environment in the origins of schizophrenia and other psychotic disorders (1). One area of research that has received particular attention is the association between social risk factors -such as urbanicity, social adversity and exclusion -and psychosis (2-4). Understanding geographical variation in the incidence of psychosis and identifying social factors that account for this variation may provide valuable insights into the etiology of, and treatment for, psychosis (1,5).In this paper, we review the evidence on: a) variation in the incidence of schizophrenia and other psychoses in terms of place; b) individual-and area-level factors that explain this variation, including social stress and exclusion; and c) potential mechanisms that link adverse urban environment and psychosis. GEOGRAPHICAL VARIATION IN INCIDENCEThe first studies on geographical variation in the incidence of schizophrenia and other psychoses were conducted in Chicago (6-9) and Bristol (10) since the 1920s.Faris and Dunham (9), in their pioneering study in Chicago, were the first to report that first admission rates of schizophrenia were highest in the city centre. While rates of schizophrenia decreased as the distance from the centre increased, rates of affective psychosis ...

HDAC1 links early life stress to schizophrenia-like phenotypes

“…A number of genes have been associated with the risk to develop schizophrenia (4)(5)(6). In addition to genetic predisposition, environmental factors, such as urbanicity (7), obstetric complications (8), or exposure to early life stress (ELS) (9,10), are known to increase the risk of developing schizophrenia. Such genome-environment interactions are mediated by epigenetic processes, including DNA methylation (DNAme) or histone modifications (11).…”

What causes psychosis? An umbrella review of risk and protective factors

“…Ethnic minority status and urbanicity may better represent true risk factors, contributing to the development of psychotic disorders through increased socio-environmental adversities 123 . In fact, the effect of both factors on the risk of developing psychotic disorders may be explained (mediated) by environmental exposures at an individual level, such as substance use, social isolation, social defeat, social fragmentation, and discrimination 124 . Interestingly, many of these exposures appear to share a common factor of social stress and defeat 125,126 , and have beenmostly indirectly -associated with various neurobiological sequelae of potential relevance to psychotic disorders 127 , such as alterations in the hypothalamic-pituitary-adrenal axis 128,129 , inflammation 130 , altered brain functioning 131,132 , reduced brain volumes 133 , and neurochemical dysfunctions 126,134,135 .…”

Assessment of dietary habits and nutritional status of depressive patients, depending on place of residence

“…High population density urban areas are characterized by high rates of crime, mortality, social isolation, environmental pollution and noise [9,10,19]. Research shows that more than half of the world population today live in urban areas, and demographic forecasts predictits continuous growth to more than 6.3 billion by 2050 [19].…”

“…As research shows, some socio-demographic factors (including age, education, marital status or place of residence) may differentiate the occurrence of depressive disorders [1,4,9,10,11]. However, the few studies that analyzed the incidence of depression depending on the place of residence have demonstrated ambiguous results.…”