Person-specific digital measurements of air pollutant exposure and biomarkers of Alzheimer's disease: Findings from a pilot study

Background: Air pollution has been almost exclusively measured by region-level ambient exposure of particulate matter (PM) from government agencies (e.g., EPA), which does not capture the potentially large within-region variation and takes no consideration of human mobility in daily life. The use of region-level PM may have systematically biased the estimated associations with Alzheimer disease (AD). Objective: To obtain pilot data on person-specific digital measurements of exposure to PM and volatile organic compounds (VOC) and to correlate them with AD biomarkers, including plasma and cerebrospinal fluid (CSF) analytes and amyloid and tau positron emission tomography (PET) signal, and to generate hypotheses about these correlations. Methods: Fifty nine older participants underwent a 7-day digital collection of exposure to PM and VOC by Atmotube Pro, a validated wearable air quality sensor. Person-specific levels of PM and VOC were correlated with AD biomarkers. Sample sizes for future studies to detect the observed correlations were estimated. Results: The first functional principal components (FFPC) of 7-day exposure to PM and VOC captured 75% to 86% of the total variation. The FFPC of PM₁, PM_2.5, PM₁₀was correlated with CSF total tau (r = 0.63, 0.60, and 0.60, respectively; p < 5%). The FFPC of VOC was marginally correlated with amyloid biomarkers (r = −0.41 with CSF Aβ_42/40, r = 0.45 with CSF Aβ₄₀, and r = 0.25 with PET amyloid centiloid). Conclusions: The pilot study generated the hypothesis that person-level air pollutant exposure to PM and VOC is associated with AD biomarkers, but larger studies are needed to test the hypothesis.