The following is a summary of “Long-term Exposure to Multiple Ambient Air Pollutants and Incident Depression and Anxiety,” published in the February 2023 issue of Psychiatry by Yang et al.

For a prospective, population-based cohort study, researchers investigated the relationship between long-term exposure to multiple air pollutants and incident depression and anxiety. 

The study utilized data from the UK Biobank, which included individuals who had never been diagnosed with depression or anxiety at baseline and had full information on exposure and covariates. The study analyzed data from May 1 to October 10, 2022. The study’s participants were recruited between March 13, 2006, and October 1, 2010. The study involved 389,185 participants (52.9% females, mean age of 56.7 [SD 8.1] years) with a median follow-up of 10.9 (IQR 10.1-11.6) years. 

The study found that the long-term estimated exposure to multiple air pollutants, including particulate matter (PM) with an aerodynamic diameter of 2.5 μm or less (PM_2.5), PM with an aerodynamic diameter between 2.5 μm and 10 μm (PM_2.5-10), nitrogen dioxide (NO₂), and nitric oxide (NO), was associated with an increased risk of depression and anxiety. In addition, the exposure-response curves were nonlinear, with steeper slopes at lower concentrations and plateauing trends at higher exposure.

Of 13,131 and 15,835 cases of depression and anxiety were diagnosed, respectively. The median (IQR) pollutant concentrations were as follows: PM_2.5, 9.9 (9.3-10.6) μg/m³; PM2.5-10, 6.1 (5.8-6.6) μg/m³; NO₂, 26.0 (21.3-31.1) μg/m³; and NO, 15.9 (11.6-20.6) μg/m³. The study found that long-term exposure to air pollutants was associated with a higher risk of depression and anxiety. The exposure-response curves were nonlinear, with steeper slopes at lower concentrations and plateauing trends at higher exposure. The highest quartile of air pollution score had hazard ratios (HRs) of 1.16 (95% CI, 1.09-1.23; P < .001) and 1.11 (95% CI, 1.05-1.17; P < .001) for depression and anxiety, respectively. PM_2.5, NO₂, and NO also showed similar trends. Subgroup analysis showed that the association between PM_2.5 and anxiety tended to be higher in males than females (quartile 4: males, 1.18; 95% CI, 1.08-1.29; females, 1.07; 95% CI, 1.00-1.14; P = .009).

The study concluded that reducing joint exposure to multiple air pollutants may alleviate the disease burden of depression and anxiety. The study also reported that the association between PM_2.5 and anxiety tended to be higher in males than in females.

Reference: https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2801116