Is the excess risk of psychosis-like experiences in urban areas attributable to altered cognitive development?

Résumé

BACKGROUND: Rates of psychotic disorder and related attenuated psychotic experiences are higher in urban areas. We examined to what degree differences between urban and rural areas could be attributed to differences in cognitive development.METHOD: Scores on the nine subscales of the schizotypal personality questionnaire (SPQ) as well as IQ and specific neuropsychological functions of memory and attention were assessed in a representative sample of 943 young army conscripts from the 49 counties of Greece.RESULTS: Young men from urban areas had higher scores on the SPQ subscale Odd beliefs/magical thinking (OR = 1.99, 95% CI: 1.42, 2.78), but lower scores on Excessive social anxiety (OR = 0.63, 95 % CI: 0.49, 0.81) and No close friends (OR = 0.42, 95% CI: 0.29, 0.62). Adjustment for demographic factors, IQ and specific neuropsychological functions did not change the results. When the lower scores on Excessive social anxiety and No close friends were taken into account, the differences on the Odd beliefs/magical thinking subscale became even more pronounced (OR = 2.33, 95% CI: 1.56, 3.49).CONCLUSIONS: Young men from urban areas are socially more competent, but display higher levels of positive psychotic experiences, which are not mediated by lower IQ or higher levels of neuropsychological impairment.