Background: : Two recent clinical reports describe an association between statin therapy and a reduction in the occurrence of Alzheimer's disease by as much as 70 %. One report is a cross-sectional analysis of discharges among three hospitals, and the other is a nested case control study drawn from ambulatory patients of general practitioners in the UK. Because neither study is a randomized trial, the association noted between statin therapy and a reduced incidence of Alzheimer's disease may have occurred because other factors, unaccounted for in the studies, may be present (so called bias) and be responsible for the observed association. However, there is an expanding body of biological and epidemiological data that makes it plausible that statin therapy may retard or prevent the pathogenesis and clinical expression of Alzheimer's disease. This review was initiated in order to find other clinical evidence that might support or refute the hypothesized benefit of statin therapy.
Objectives: : The purpose is to review the evidence that treatment with statins reduces the risk of Alzheimer's disease.
Search strategy: : The following data bases were searched: Specialised Register of the Cochrane Dementia and Cognitive Improvement Group, MEDLINE (1966-2000/12), EMBASE (1980-2000/12), and Psych Info (1987-2000/11). Search terms included statins,lovastatin, pravastatin, simvastatin, alzheimer*, dement*, cogn*.
Selection criteria: : In order to be selected, trials needed to be randomized, doubled blinded, and of sufficient duration( probably years rather than weeks or months) to ascertain the preventive potential of statin therapy.
Data collection and analysis: : Data were to be extracted independently by two reviewers and pooled where appropriate and possible. The pooled odds ratios (95% CI) or the average differences were to be estimated.
Main results: : There were no randomized trials found in the search.
Reviewer's conclusions: : There is no good evidence to recommend statins for reducing the risk of Alzheimer's disease. There is, however, a growing body of biological, epidemiological, and limited but non-randomized clinical evidence that lowering serum cholesterol may retard the pathogenesis of Alzheimer's disease. Mounting the clinical studies to determine the potential benefit of statin therapy should be a high priority for future research agendas.