Long-Term Exposure to PM2.5 and Risk of Incident Dementia: A Systematic Review and Meta-Analysis of Cohort Studies.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational cohort studies
PubMed 42087308 · doi:10.1097/CRD.0000000000001287
What was done
The authors conducted a systematic review and meta-analysis of cohort studies evaluating the association between chronic fine particulate matter (PM2.5) exposure and incident dementia. From 909 identified records, 15 cohort studies covering approximately 65 million participants in Europe, Asia, and North America were included. Hazard ratios were standardized to a 1 ug/m3 increase in PM2.5 exposure using logarithmic transformation and pooled using a random-effects model.
What was found
Long-term PM2.5 exposure was associated with an increased risk of incident dementia, yielding a pooled hazard ratio of 1.04 (95% confidence interval 1.01-1.06) per 1 ug/m3 increase. Substantial heterogeneity was observed across the included studies (I2 = 88.3%).
Why it matters
This review aggregates large-scale international cohort data to quantify the relationship between chronic ambient air pollution and dementia onset. It highlights PM2.5 reduction as a potential population-level target for mitigating neurodegenerative disease risk.
Limits
All included data derive from observational cohort studies susceptible to unmeasured confounding and exposure misclassification. The analysis shows substantial between-study heterogeneity (I2 = 88.3%). The abstract does not report subgroup analyses by dementia subtype or details regarding exposure assessment methods.
Cited by
- supports Epidemiological studies demonstrate that living in large cities with air pollution increases the risk of developing dementia.