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Background Dementia is a global public health challenge, with Alzheimer's disease (AD) and vascular dementia (VaD) being the most prevalent subtypes. Air pollution is a potential risk factor for dementia, but few studies separate AD and VaD. Objective This study aims to investigate whether exposure to air pollution is associated with the incidence of AD and VaD. Methods This study involved 30,247 participants from the Malmö Diet and Cancer Study (1991–2014), with 1216 AD cases (including mixed type) and 531 VaD cases, clinically validated. Long-term exposure to PM 2.5 and NO x was modeled using the past 5-years or 10-year mean concentration with 50m × 50 m spatial resolution at residential addresses. The association between AD and VaD and air pollution was assessed using adjusted Cox-proportional hazards. Results For AD the hazard ratios (HRs (95% CIs) were 1.06 (0.89–1.27) for PM 2.5 and 1.08 (0.96–1.22) for NO x per interquartile range (IQR) increase in past 10-year mean pollution-levels. Nonsignificant associations were observed in two-pollutant models. For past 5-year exposure, we observed a statistically significant association between NO x and AD 1.14 (1.00–1.30). For VaD, we found no evidence for associations in any models. Conclusions We found that while both PM 2.5 and NO x seemed linked to increased AD risk in single-pollutant models, only the associations with NO x remained in two-pollutant models, particularly for exposures in the past five years. No associations were observed for VaD. The results underscore the importance of distinguishing dementia subtypes, identifying critical exposure windows, and applying multi-pollutant models in future studies.
Alzhrani et al. (Mon,) studied this question.