Overcrowding, conflicts over dwelling space, and mental health: a longitudinal causal mediation analysis in Chile’s social housing context

Abstract Background Access to adequate housing is a current challenge in an increasingly urban worldwide context. Housing is fundamental to mental health; yet causal evidence remains limited due to the complexity of housing exposure in longitudinal studies. We evaluated whether conflicts over space mediate the relationship between household overcrowding and mental health among Chilean social housing residents, with attention to gender differences. Methods We conducted a three-wave longitudinal study with 6-month intervals (2018–2022) in two peri-urban social housing neighborhoods in central Chile. We measured household overcrowding (> 2 people per sleeping room) at baseline, conflicts over space at wave 2, and general mental health using General Health Questionnaire-12 (GHQ-12) dimensions at wave 3 among 660 participants (569 women and 91 men). Because of the small sample size in the men group, the mediation analysis is only for 477 women. We employed causal mediation analysis using quasi-Bayesian methods (1000 iterations) and adjusting for confounders (gender, age, education, household composition, study site, and housing renovation). Secondly, we use structural equation modeling (SEM) to test serial and parallel mediation and to model measurement error and covariance between GHQ-12 dimensions. Results Overcrowding prevalence was 21–25% in women and 10–14% in men. Causal mediation analysis showed that overcrowding has no direct effect on mental health. However, conflicts over space mediated the relationship between overcrowding and dysphoria symptoms (β = 0.20; CI: 0.05, 0.43) in women. SEM shows a significant direct effect of overcrowding on conflicts over space (β = 1.80, p = .001), but no significant indirect effect (β = 0.037, p = .068), nor for the other GHQ-12 dimensions. Conclusions We found no total effect, but an indirect effect of overcrowding on women’s dysphoria through increased conflicts over space. Social housing policies should address dwelling size alongside household social dynamics regarding space.