Smoking and the Occurence of Alzheimer's Disease: Cross-Sectional and Longitudinal Data in a Population-based Study

Abstract

The authors tested the hypothesis that smoking exerts a protective effect on Alzheirmer's disease or dementia in a population-based cohort of 668 people aged 75–101 years (Sweden). Smoking was negatively associated with prevalent Alzheimer's disease (adjusted odds ratio = 0. 6, 95% confidence interval 0. 4–1.1) and dementia (adjusted odds ratio = 0. 6, 95% confidence interval 0. 4–1.0). Over 3-year follow-up (1989–1992), the hazard ratios of incident Alzheimer's disease and dementia due to smoking were 1. 1 (95% confidence interval 0. 5–2.4) and 1. 4 (95% confidence interval 0. 8–2.7). Mortality over 5-year follow-up was greater among smokers in demented (hazard ratio = 3. 4) than nondemented (hazard ratio= 0. 8) subjects. Smoking does not seem protective against Alzheimer's disease or dementia, and the cross-sectional association might be due to differential mortality. Am J Epidemiol 1999; 149:640–4.