A bibliometric and systematic review of the global impact of air pollution on Alzheimer's disease: Insights from cohort studies

Background Emerging evidence highlights the potential role of environmental factors, particularly air pollution, in the development and progression of Alzheimer's disease (AD). Air pollutants may contribute to neurodegenerative processes through mechanisms such as oxidative stress, neuroinflammation, and disruption of the blood–brain barrier. Objective This review aims to systematically evaluate global cohort studies investigating the association between long-term exposure to key air pollutants—specifically particulate matter (PM2.5), nitrogen dioxide (NO 2 ), and ozone (O 3 )—and the risk of AD. Methods A total of 31 peer-reviewed cohort studies were included based on a structured search strategy. We analyzed epidemiological outcomes, exposure assessment methodologies, and geographic trends. Additionally, a bibliometric analysis was conducted using VOSviewer to identify major contributors and emerging research themes. Results Findings indicate a consistent association between PM2.5 exposure and increased risk of AD, independent of genetic predisposition and lifestyle factors. Proposed biological mechanisms include oxidative stress, microglial activation, blood–brain barrier disruption, and amyloid-β accumulation. Bibliometric mapping revealed regional concentration of research in North America, Europe, and East Asia, with increasing global interest over the past decade. Conclusions There is mounting evidence linking air pollution to Alzheimer's disease. Advances in exposure assessment have improved the accuracy of epidemiological findings. Public health policies targeting air quality control and further studies on molecular and early-life exposures are essential to mitigate the neurotoxic effects of environmental pollutants.