Explaining the association between urbanicity and psychotic-like experiences in adolescence: The indirect effect of urban exposures
Urban living is a growing worldwide phenomenon with more than two-thirds of people expected to live in cities by 2050. Although there are many benefits to living in an urban environment, urbanicity has also been associated with deleterious health outcomes, including increased risk for psychotic outcomes particularly when the urban exposure occurs in adolescence. However, the mechanisms underlying this association is unclear. Here, we utilize one-year follow-up data from a large (N=7,979), nationwide study of adolescence in the United States to clarify why urbanicity might impact psychotic-like experiences (PLE) by looking at the indirect effect of eight candidate urbanicity-related physical (e.g., pollution) and social (e.g., poverty) exposures. Consistent with other work, we find that of the evaluated exposures related to urbanicity, several were also related to increased number of PLE and associated distress: PM2.5, proximity to roads, census-level homes at-risk for exposure to lead paint, census-level poverty, and census-level income-disparity. Mediation analysis revealed that a substantial proportion the urbanicity-PLE association could be explained by PM2.5 (23% of the urbanicity-PLE number association), families in poverty (57-67% of the urbanicity-PLE number and distress association), and income disparity (55-66% of the urbanicity-PLE number and distress association). Together, these findings suggest that specific urban-related exposures might help to explain why those in urban environments are disproportionately at-risk for psychosis and point towards areas for public health intervention.