(HealthDay News) — Air pollution may be a risk factor for dementia, according to the results of a meta-analysis published online April 5 in The BMJ.
Elissa H. Wilker, ScD, from the Harvard T.H. Chan School of Public Health in Boston, and colleagues conducted a systematic literature review to identify studies examining the role of air pollutants in the risk for dementia.
Based on 14 included studies in the meta-analysis, the researchers found that per 2 μg/m3 particulate matter <2.5 μm in diameter (PM₂.₅), the overall hazard ratio (HR) for dementia was 1.04 (95 percent confidence interval [CI], 0.99 to 1.09). Findings were similar for the seven studies that used active case ascertainment (HR, 1.42; 95 percent CI, 1.00 to 2.02), as well as the seven studies that used passive case ascertainment (HR, 1.03; 95 percent CI, 0.98 to 1.07). Per 10 μg/m3 nitrogen dioxide, the overall hazard ratio was 1.02 (95 percent CI, 0.98 to 1.06; nine studies), and per 10 μg/m3 nitrogen oxide, the HR was 1.05 (95 percent CI, 0.98 to 1.13; five studies). No association with dementia was seen for ozone (per 5 μg/m3 HR, 1.00; 95 percent CI, 0.98 to 1.05; four studies).
“The findings support the public health importance of limiting exposure to PM₂.₅ and other air pollutants and provides a best estimate of effect for use in burden of disease and policy deliberations,” the authors write.
The study was supported by the US National Institutes of Health and Biogen.
