Associations of long-term exposure to source-specific PM2.5, lifestyle, and genetic susceptibility with dementia risk: a prospective cohort study.

OBJECTIVES

The impact of source-specific PM2.5 on dementia and its subtypes is limited. We aimed to investigate the association between source-specific PM2.5 and the risk of incident dementia and explore whether genetic susceptibility and lifestyle modified these associations.

METHODS

We used Cox models with time-varying exposure measurements to evaluate the associations of source-specific PM2.5 with incident dementia. A polygenic risk score and a lifestyle score were constructed to assess whether those factors could modify the effect of source-specific PM2.5 on dementia risk.

RESULTS

During a median follow-up of 11.9 years, a total of 5,648 incident all-cause dementia cases were identified. The adjusted hazard ratios for dementia associated with an interquartile range increase in PM2.5 from domestic, transport, other transport, and industry sources were 1.05 (1.01, 1.08), 1.12 (1.04, 1.21), 1.12 (1.06, 1.19), and 1.07 (1.03, 1.11), respectively. For the combined associations, Participants with high levels of source-specific PM2.5 exposure and high genetic susceptibility had a greater risk of incident dementia compared to those with the lowest pollutant exposure and lowest genetic risk (∼236% to 352%). A similar pattern was observed for the joint relationship between source-specific PM2.5 and lifestyle factors.

CONCLUSIONS

Higher source-specific PM2.5 exposure levels were associated with a higher risk of incident dementia. Our findings indicate that source-specific reduction strategies and targeted preventive approaches for high-risk groups might be associated with a lower risk of incident dementia.