Air Pollution, Functional Brain Network Connectivity, and Cognitive Aging: A Scoping Review

This scoping review maps and synthesizes existing evidence on the association between air pollution exposure and functional brain network connectivity, situated within the context of cognitive aging and neurodegenerative vulnerability across the lifespan. The review was conducted in accordance with the Joanna Briggs Institute (JBI) methodology for scoping reviews and reported following the PRISMA-ScR checklist. Database searches were conducted across PubMed/MEDLINE, Scopus, and Embase for English-language studies published from 2006 onwards. TRANSPARENCY ADDENDUM (June 2026): The following refinements were made during manuscript preparation and are disclosed here for transparency. First, the review title was revised from 'Air Pollution and Functional Brain Networks: A Scoping Review of Implications for Cognitive Aging' to 'Air Pollution, Functional Brain Network Connectivity, and Cognitive Aging: A Scoping Review' to comply with journal title-style requirements, which discourage vague constructions such as 'implications for,' and to more precisely reflect the review's three core concept domains. Second, one source included in the final set at the time of registration was subsequently excluded during the synthesis stage of manuscript preparation upon closer examination of its reported outcomes, as it was determined not to report an empirical measure of functional brain connectivity consistent with the predefined inclusion criteria; this reduced the final included set from nine to eight studies. Third, the research question wording was refined for clarity and journal style compliance: RQ1 now specifies that evidence is examined 'as situated within cognitive aging and neurodegenerative vulnerability research'; RQ2 now additionally includes age groups as a characteristic examined; and RQ3 now refers to 'key evidence gaps and future research priorities' rather than 'implications of existing evidence and gaps warranting future investigation.' Fourth, the population criterion was clarified to explicitly include developmental populations where findings were framed in terms of life-course relevance to later cognitive trajectories, consistent with the original eligibility criteria as written in the registered protocol. In all other respects, the eligibility criteria, search strategy, analytical approach, and included studies remain consistent with this registered protocol.