Associations Between Air Pollution and relative Leukocyte Telomere Length Among Northern Swedish Adults: Insights from the Betula Observational Study

Air pollution is increasingly discussed as a risk factor for dementia, but the biological mechanisms are not yet fully understood. Cellular integrity markers like telomere length are relevant to investigate in relation to air pollution exposure in this context, as they are associated with aging and dementia. Previous studies on air pollution and telomere length have somewhat mixed results, which may partly be due to differences in air pollution modelling, composition, and concentrations. The study aimed to investigate the relationship between source-specific air pollution exposure and telomere length in a low-level air pollution area. Data were obtained from the Betula project, a longitudinal study in Northern Sweden dedicated to studying aging, memory and dementia. A total of 519 participants who were recruited between 1988 and 1995 were included, whose relative telomere length was measured, and who were followed-up with respect to dementia for more than 20 years. To estimate annual mean air pollution concentrations, a dispersion model linked to each participants residential address was employed. We conducted linear regression to explore the associations between annual mean air pollution concentrations at participants residences and relative leukocyte telomere length. In the whole sample, there was no support for air pollution to affect telomere length, with regression slope estimates close to zero and p-values >0.10. There were tendencies for a positive association of longer telomere length and higher exposure to air pollution among individuals who were later diagnosed with dementia (N = 74), but these findings were not conclusive (p-values >0.10). The findings raise questions about susceptibility to air pollution and the state of the inflammatory response in individuals who later will develop dementia. Given the imprecise nature of these estimates, caution is advised in their interpretation however, and validation in other studies is essential.