Fine particulate matter, vitamin D, physical activity, and major depressive disorder in elderly adults: Results from UK Biobank

The present study aims to investigate the association between PM2.5 exposure and major depressive disorder, and to examine whether vitamin D and physical activity could attenuate the impact of PM2.5 on major depressive disorder.39168 elderly adults (age≥60 years) who had valid estimates on exposure of PM2.5 in 2010 and data on major depressive disorder were extracted from the UK Biobank. Major depressive disorder was assessed by lifetime experience of mild, moderate, and severe major depression with validated instruments. Logistic regression models were used to estimate the association between PM2.5 exposure and major depressive disorder.A total of 9079 participants had major depressive disorder, with a prevalence of 23.2%. The odds ratio (OR) of major depressive disorder was 1.096 (1.023, 1.175) for participants in the highest quartile compared with the lowest quartile of PM2.5. The correlation of PM2.5 with major depressive disorder generally increased with the decreasing levels of vitamin D. For instance, in participants with the highest quartile of PM2.5, the corresponding ORs were 1.141 (0.951, 1.369), 1.232 (1.027, 1.478), 1.286 (1.072, 1.543), and 1.390 (1.159, 1.667) for those who had adequate, desirable, insufficient, and deficient levels of vitamin D, respectively. Additionally, significant modification effects of physical activity on the relationship between PM2.5 and major depressive disorder were also observed.Our study suggests that high levels of vitamin D and physical activity may attenuate the relationship between PM2.5 and major depressive disorder among elderly adults.