Do statins reduce risk of incident dementia and Alzheimer disease? The Cache County Study.

Background: Prior reports suggest reduced occurrence of dementia and Alzheimer disease (AD) in statin users, but, to our knowledge, no prospective studies relate statin use and dementia incidence.

Objective: To examine the association of statin use with both prevalence and incidence of dementia and AD.

Design: Cross-sectional studies of prevalence and incidence and a prospective study of incidence of dementia and AD among 5092 elderly residents (aged 65 years or older) of a single county. Participants were assessed at home in 1995-1997 and again in 1998-2000. A detailed visual inventory of medicines, including statins and other lipid-lowering agents, was collected at both assessments.

Main Outcome Measures: Diagnosis of dementia and of AD.

Results: From 4895 participants with data sufficient to determine cognitive status, we identified 355 cases of prevalent dementia (200 with AD) at initial assessment. Statin use was inversely associated with prevalence of dementia (adjusted odds ratio, 0.44; 95% confidence interval, 0.17-0.94). Three years later, we identified 185 cases of incident dementia (104 with AD) among 3308 survivors at risk. Statin use at baseline did not predict incidence of dementia or AD (adjusted hazard ratio for dementia, 1.19; 95% confidence interval, 0.53-2.34; adjusted hazard ratio for AD, 1.19; 95% confidence interval, 0.35-2.96), nor did statin use at follow-up (adjusted odds ratio for dementia, 1.04; 95% confidence interval, 0.56-1.81; adjusted odds ratio for AD, 0.85; 95% confidence interval, 0.32-1.88).

Conclusions: Although statin use might be less frequent in those with prevalent dementia, we found no association between statin use and subsequent onset of dementia or AD. Further research is warranted before costly dementia prevention trials with statins are undertaken.