Long-term air pollution exposure and incident migraine in middle aged and older adults: A population-based study

The literature examining the association between air pollution and migraine is sparse and results are mixed. This study aimed to investigate the effect of long-term exposure to particulate matter (PM)10, PM2.5, and their specific components, including black carbon, organic matter, ammonium, sulfate, and nitrate, on the risk of migraine.

The retrospective cohort study was performed on 5187 migraine-free participants ≥45 years old. The participants were enrolled from the China Health and Retirement Longitudinal Study in 2011 and followed up until 2018. Exposure levels of the participants were assessed using PM concentrations at 1-km spatial resolution during the follow-up period. Furthermore, the study investigated the association of PM exposure with migraine and the synergistic effects of PM2.5 components on migraine risk.

During 7.9 years of average follow-up, a total of 1137 new-onset incident migraine attacks were documented. A 1 μg/m³ increase in PM10 and PM2.5 exposures was associated with increased migraine risks, with respective adjusted hazard ratios of 1.02 (95% confidence interval [CI], 1.01-1.03) and 1.05 (95% CI, 1.03-1.06). When considering the combined effects of all mixture components, a simultaneous one-quantile increase in PM2.5 exposure was significantly associated with a 1.10-fold increase in migraine risk (95% CI, 1.03-1.17). The overall mixing effect was primarily driven by the positive contribution from black carbon (weight = 0.487), sulfate (weight = 0.295), and organic matter (weight = 0.218).

Long-term exposure to PM10 and PM2.5 was found to be associated with increased migraine risk in the middle-aged and older adult Chinese population. Black carbon, sulfate, and organic matter may be the primary contributors to the adverse effects of PM2.5 on migraine risk; however, further studies with more rigorous designs are required to validate these findings.