The impacts of neighbourhood violence on mental health consultations among residents of low-income neighbourhoods in Rio de Janeiro: a retrospective cohort analysis.

BACKGROUND: Violence is associated with poor mental health outcomes. However, longitudinal evidence from urban settings with endemic violence – particularly in low- and middle-income countries such as Brazil – remains limited. This study investigates the association between neighbourhood violence, including drug-gang conflicts and police operations, on mental health consultations in Rio de Janeiro. METHODS: A cohort of 1,358,943 individuals observed from January 2010 to December 2016 was analysed. Individuals were considered exposed to violence if a violent event occurred within 250 m of the primary healthcare clinic they attended. Using cross-sectional Poisson regression models, we examined which sociodemographic groups were more exposed to neighbourhood violence, and fixed effects panel Poisson regression assessed the association between neighbourhood violence and PHC consultations for mental health conditions. RESULTS: Over two thirds of the cohort (n = 913,125) were exposed to at least one neighbourhood violent event in the study period, most of which were police-related shootings (70.4%). Females, Black individuals, and younger adults were more likely to experience neighbourhood violence, particularly drug-gang violence. Exposure to two and three neighbourhood violent events in a month was associated with a 5% (IRR: 1.05; 95% CI: 1.02–1.07; p < 0.001) and 8% (IRR: 1.08; 95% CI: 1.04–1.12; p < 0.001) increase in mental health-relatedprimary healthcare consultations, respectively, while five or more events were linked to a 7% decrease (IRR: 0.93; 95% CI: 0.89–0.97; p < 0.001). Lagged analyses showed that exposure to 2–4 violent events per month was associated with increased mental health consultations, particularly 2–4 months after violence exposure. Increases in mental health consultations following high levels of violence exposure were observed among individuals aged 19–34 and 65 + years, but were lower among those with a high school education or higher. CONCLUSIONS: Neighbourhood violence in Rio de Janeiro was associated with increased mental health-related primary healthcare consultations both immediately and two to four months following violence exposure.