Longer Exposure to Air Pollution Comes With Increased Risk for Depression, Anxiety

Long-term exposure to multiple air pollutants, including particulate matter, nitrogen dioxide (NO₂), and nitric oxide (NO), have been linked with an increased risk of depression and anxiety according to new study results published in JAMA Psychiatry.

“Study results suggest that estimates of long-term exposure to multiple air pollutants was associated with increased risk of depression and anxiety,” wrote first author Teng Yang, BD, Department of Occupational and Environmental Health Sciences, Peking University School of Public Health, Beijing, China, and co-authors. “Reductions in joint exposure to multiple air pollutants may alleviate the disease burden of depression and anxiety.”

The prospective, population-based cohort study included 389,185 participants (mean [SD] age, 56.7 [8.1] years, 205,855 female individuals [52.9%]) from the UK Biobank, none of whom had been diagnosed with anxiety or depression at baseline.

The exposures under examination were annual mean air pollution concentrations of particulate matter (PM) with aerodynamic diameter of 2.5 µm (PM_2.5) and PM with aerodynamic diameter between 2.5 µm and 10 µm (PM_2.5-10). The researchers estimated NO₂ and NO levels for each participant’s residential address using the land use regression model. They also estimated joint exposure to air pollution reflected by air pollution score using principal components analysis.

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During a median (IQR) follow-up of 10.9 (10.1-11.6) years, a total of 13,131 participants were diagnosed with depression while 15,835 were diagnosed with anxiety. The median (IQR) concentration of PM_2.5 was 9.9 (9.3-10.6) mg/m3; of PM_2.5-10 was 6.1 (5.8-6.6) µg/m³; of NO₂ was 26.0 (21.3-31.1) µg/m³; and of NO was 15.9 (11.6-20.6) µg/m³.

“Long-term estimated exposure to multiple air pollutants was associated with increased risk of depression and anxiety, and the exposure-response curves were nonlinear, with steeper slopes at lower concentrations and plateauing trends at higher exposure,” the authors noted.

The hazard ratios (HRs) and 95% CIs for depression and anxiety were 1.16 (95% CI, 1.09-1.23; P < .001) and 1.11 (95% CI, 1.05-1.17; P < .001) in the highest quartile compared with the lowest quartile of air pollution score, respectively. Similar trends were shown for PM_2.5, NO₂, and NO. Subgroup analysis showed the association between PM_2.5 and anxiety tended to be higher in male individuals than in female individuals (quartile 4: male individuals, 1.18; 95% CI, 1.08-1.29; female individuals, 1.07; 95% CI, 1.00-1.14; P = .009).

“Air pollution exposure may affect the central nervous system by inflammatory and oxidative stress pathways through olfactory receptor neurons, the trigeminal nerve, or the systemic circulation,” the authors said. “Further research is needed to clarify the mechanisms that underlie the association between air pollution and mental health.”

Reference

Yang T, Wang J, Huang J, et al. Long-term exposure to multiple ambient air pollutants and association with incident depression and anxiety. JAMA Psychiatry. Published online February 1, 2023. doi: 10.1001/jamapsychiatry.2022.4812