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City living may not always increase risk for psychotic disorders

James B. Kirkbride

Living in urban areas may not always be associated with a higher rate of psychotic disorders, according to a viewpoint published in JAMA Psychiatry.

Numerous epidemiologic studies previously reported have shown a link between higher rates of schizophrenia and city living, suggesting that environmental factors play a causal role in urban settings, James B. Kirkbride, PhD, from the division of psychiatry, University College London, and colleagues wrote.

Prior evidence supports the associations between social factors and higher rates of nonaffective psychotic disorders in urban settings. Furthermore, previous neurobiological research has found that healthy volunteers from more urban environments showed heightened activity in the amygdala and perigenual anterior cingulate cortex areas of the brain after stress.

“Nonetheless, a definitive statement about causality (or refutation of it) awaits results of ongoing efforts to produce convergent evidence that elucidates the exact mechanisms through which some or all of these factors account for differential rates of psychotic disorder in some urban populations,” Kirkbride and colleagues wrote. “It does not follow, however, that city living should be associated with psychotic disorders in all contexts.”

Contrary to established findings, newly published data from the World Health Survey revealed that urban living may not be linked to a higher risk for psychosis in low- and middle-income countries. Using World Health Survey data to examine urban-rural differences in psychosis emphasizes the “need for a new, global vista, long overdue in epidemiologic studies of city living and psychosis,” Kirkbride and colleagues wrote.

Because global investigations of psychotic experiences can predict adverse psychopathologies, Kirkbride and colleagues explained that contextualizing cultural variation between and within different countries should be studied in the future.

“Just as we should not expect a universal association between city living and psychotic disorders, nor should we infer from pooled results on [psychotic experiences] across heterogeneous, uncharacterized settings that such associations do not exist,” they concluded. “Rather, we should anticipate and seek to understand the causes of heterogeneous associations between city living and psychotic disorders as we develop a global purview of the epidemiology of psychotic disorders in a fast-changing world.” – by Savannah Demko

Disclosure: Kirkbride reports support from a Sir Henry Dale Fellowship, which is jointly funded by the Wellcome Trust and the Royal Society.