A good move for health?: Analyzing urban exposure trajectories of residential relocation and mental health in populations in Bradford

Residential relocation can be leveraged as a natural experiment. This study examined the changes in environmental exposures due to residential relocation in two samples of within-city movers in Bradford (UK); 2089 residents (66% women, mean [SD] age, 47.80 [19.88] years) with preexisting common mental disorders-related prescriptions and 12,699 residents (60% women, mean [SD] age, 42.47 [17.40] years) without the same prescriptions at baseline (January-April 2021). Study data were extracted from National Health Service health records. The outcome was the presence of an active prescription for anxiolytics or antidepressants (yes/no) 1 year after relocation (January-April 2022). Change scores were calculated for several exposures, including the normalized difference vegetation index, distance decay to green spaces, coarse (PM₁₀) and fine particulate matter (PM_2.5), and nitrogen dioxide (NO₂) at pre- and postmove addresses. Logistic regression models were used for each change score exposure, adjusting for covariates selected using a direct acyclic graph validated against the data. Participants without prescriptions at baseline were likely to relocate to less green and less polluted areas compared with those with preexisting medication. A total of 15% of participants without prescriptions at baseline had an active prescription at follow-up. For these, increases in normalized difference vegetation index were associated with lower odds of having active prescriptions at follow-up [OR (odds ratio) = 0.93 (95% confidence interval [CI] = 0.88, 0.98), <i>P</i> = 0.007], whereas increases in PM_2.5 [OR = 1.1 (95% CI = 1.04, 1.16), <i>P</i> < 0.001] and PM₁₀ [OR = 1.12 (95% CI = 1.06-1.19), <i>P</i> < 0.001] concentrations were associated with higher odds. Changes in environmental exposures due to residential relocation showed an influence on mental health only for those participants without active prescriptions in the baseline.