INTRODUCTION
Our understanding of how PM2.5 impacts cognitive functioning is limited. Systemic inflammation processes may play a role in mediating this effect.
METHODS
This prospective cohort study used data from 66,254 participants aged 18+ between 2006 and 2015 from the Dutch Lifelines cohort study. Causal mediation analysis was conducted to examine the impact of ambient PM2.5 exposure on cognitive processing time (CPT), using the change in WBC count and its subtypes as potential mediators.
RESULTS
Heightened PM2.5 exposure was associated with slower CPT (Total Effect = 81.76×10-3, 95% CI 59.51×10-3-105.31×10-3). The effect was partially mediated via increased WBC count (Indirect Effect = 0.42×10-3, 95% CI 0.07×10-3-0.90×10-3), which was particularly driven by an increase in monocytes (Indirect Effect = 0.73×10-3, 95% CI 0.24×10-3-1.31×10-3).
DISCUSSION
Systemic inflammation processes may partially elucidate the adverse PM2.5 effects on cognitive functioning, and why lower levels of systemic inflammation may help contain its neurotoxic effects.