Decreased prevalence of Alzheimer disease associated with 3-hydroxy-3-methyglutaryl coenzyme A reductase inhibitors

Context: Increasing evidence suggests that cholesterol plays a role in the pathophysiology of Alzheimer disease (AD). For instance, an elevated serum cholesterol level has been shown to be a risk factor for AD. Objective: To determine whether patients taking 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), which are a group of medicines that inhibit the synthesis of cholesterol, have a lower prevalence of probable AD. Design: The experiment uses a cross-sectional analysis comparing the prevalence of probable AD in 3 groups of patients from hospital records: the entire population, patients receiving 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (hereafter referred to as the statins), and patients receiving medications used to treat hypertension or cardiovascular disease. Patients: The subjects studied were those included in the computer databases of 3 different hospitals for the years October 1, 1996, through August 31, 1998. Main Outcome Measures: Diagnosis of probable AD. Results: We find that the prevalence of probable AD in the cohort taking statins during the study interval is 60% to 73% (P<.001) lower than the total patient population or compared with patients taking other medications typically used in the treatment of hypertension or cardiovascular disease. Conclusions: There is a lower prevalence of diagnosed probable AD in patients taking 2 different 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors-lovastatin and pravastatin. While one cannot infer causative mechanisms based on these data, this study reveals an interesting association in the data, which warrants further study.