Evidence that the impact of hearing impairment on psychosis risk is moderated by the level of complexity of the social environment

Abstract Background It has been suggested that part of the increased vulnerability for psychosis in individuals with hearing impairment (HI) is the consequence of a decreased ability to form correct representations of the social world and attributions of intention of others. It was therefore hypothesized that associations between HI and psychosis risk would be sensitive to contextual variables representing higher level of social complexity, conceptualized as the population density of the social environment (‘urbanicity’). Methods Urbanicity and objective HI were assessed in the Maastricht Aging Study (MAAS), a longitudinal study of 1,823 participants from the general population in Maastricht, the Netherlands. Participants were tested at baseline (T0) and at 6-year (T2) and 12-year follow-up (T4). The degree to which the association between HI (T0-T2) and psychotic experiences at T4 was moderated by T0 urbanicity was examined. Results The association between HI and psychosis was conditional on level of urbanicity (interaction χ2 = 7.51, p = .006), with low effect size in non-urbanized areas (b = -0.81, 95% CI:-2.98, 1.36) and high effect size in the most urbanized areas (b = 2.56, 95% CI: 0.47, 4.65). Although social isolation (b = 1.74, p = .022) and loneliness (b = 0.61, p < .001) were both associated with psychosis, they could not explain the observed interaction. Conclusion The findings suggest that level of complexity of the social world, in interaction with the individual's ability to correctly process this information, may impact on risk for psychotic experiences.