Dr. Achim Regenauer, Chief Medical Officer, discusses a newly published study that links air pollution to the occurrence of common neurodegenerative diseases, namely Alzheimer’s and Parkinson’s disease, the two fastest-growing neurological conditions in the world.
Air pollution is known to be linked to many adverse health outcomes, primarily to respiratory disease. There’s also a growing body of evidence that long-term exposure to air pollution in the form of fine particulate matter (PM2.5, particles or droplets in the air that are 2.5 microns or less in width) is associated with the mortality of cardiovascular disease, such as heart attack and stroke1.
Linking yet more adverse health outcomes to air pollution, a large-scale longitudinal cohort study of 63 million Medicare beneficiaries (aged ≥65 years) – published recently in The Lancet2– has established a linear relationship between long-term exposure to PM2.5 air pollution (assessed by US postcode and measured by more than 2,000 nationwide measuring stations) and the risk of a first hospital admission for Alzheimer’s or Parkinson’s disease. The main relevant confounders of age, ethnicity and socio-economic status were all accounted for in the study. Furthermore, it was observed that the diagnosis of both diseases increased linearly with increasing PM2.5 concentrations – for every 5 µg/m3 increase in annual PM2.5 concentrations, a 13% increased risk of Parkinson’s or Alzheimer’s disease – this was observed even at levels below the current US national standard for PM2.5 (a maximum annual mean PM2.5 of 12 μg/m³). So, although concentrations of PM2.5 have fallen significantly since 20003 (figure 1), this new study also indicates that there’s no safe concentration threshold for PM2.5.
Figure 1: Annual emissions of air pollutants, United States, 1970 to 2016. Values indexed to levels in the first year of data, first year data values normalised to 100. Source: Our World in Data3.
Based on the study’s design, researchers were able to establish a clear linear association between air pollution (in the form of PM2.5) and the occurrence of neurodegenerative disease (Alzheimer’s and Parkinson’s disease). The link to causation, however, has not yet been proven, though it seems plausible that fine particulate matter inhaled into the lungs and transported via the bloodstream to the brain could ultimately, via chronic inflammation, lead to neurodegenerative diseases of the brain.
Fine particulate matter as an emerging risk factor is being monitored on an ongoing basis by our Life & Health researchers. With air pollutant concentrations being a significant risk factor for common diseases of the lung, heart and now also the brain, there may be implications here for life insurance product design, underwriting and pricing, particularly in highly polluted areas and for portfolios with older insureds.
1 PM2.5 air pollution and cause-specific cardiovascular disease mortality https://pubmed.ncbi.nlm.nih.gov/31289812/
2 Long-term effects of PM2·5 on neurological disorders in the American Medicare population: a longitudinal cohort study; https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(20)30227-8/fulltext; PDF https://www.thelancet.com/action/showPdf?pii=S2542-5196%2820%2930227-8
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