A critical review of potential modifiers of air pollutant associations with dementia and related outcomes.

BACKGROUND: Air pollution has been linked with poor cognitive and brain health, including Alzheimer's Disease and Related Dementia (ADRD). However, whether specific individuals are more susceptible than others remains unclear. PURPOSE: We aimed to review potential modifiers of the air pollution-cognitive/brain health association and identify subgroups potentially susceptible to adverse effects of air pollution exposure. METHODS: We identified published, peer-reviewed articles in the Embase and Medline databases through the Ovid and PubMed search platforms and used Covidence, an online software tool, to extract relevant data from eligible articles. We then systematically reviewed and summarized the evidence on how health behaviors, genetic/molecular factors, environmental factors, and individual factors modify the association between ambient air pollution and cognitive/brain health. RESULTS: Seventy-four publications, out of 6372 relevant publications, met the eligibility criteria and were included in this review. Available studies suggested that race/ethnicity, geographic location, apolipoprotein E (APOE) e4 allele, socioeconomic status (SES), body mass index (BMI), and diet may modify the air pollution-ADRD association, and that age and education do not, although the available evidence precludes firm conclusions. Limited reporting precludes conclusions about other modifiers. CONCLUSION: Efforts to reduce the harmful effects of air pollution exposure should consider sensitive groups. The current literature suggests differential susceptibility to the adverse effects of air pollution on cognitive and brain health. Future studies should include standardized reporting of effect modification for the likely modifiers identified here, allowing for more robust conclusions.