Longitudinal Data in a Population-based Study

The authors tested the hypothesis that smoking exerts a protective effect on Alzheimer'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. aged; Alzheimer's disease; dementia; smoking In spite of numerous studies published in the past few years on the topic, the effect of smoking on Alzheimer's disease and dementia remains uncertain. Most studies have reported inconclusive results (1-14) or an increased risk of Alzheimer's disease amon