Clinical Question: Are statins associated with a decreased risk of developing dementia?

Setting: Population-based

Study Design: Cohort (prospective)

Synopsis: The authors of several case-control studies have suggested that statin use is associated with a lower risk of developing dementia. Because these kinds of studies have many limitations, they are among the weakest designs from which causal inferences can be drawn. In this study, researchers went a step further and annually evaluated almost 2,800 patients older than 65 years who did not have dementia. It is unclear if the evaluators knew whether the patients used statins. The number of patients who took statins is not stated.

Researchers followed the patients for a median of five years and had more than 13,000 person-years in the group of patients receiving no lipid-lowering drugs, nearly 1,300 person-years in those receiving statins, and approximately 500 person-years in a group receiving nonstatin lipid-lowering drugs. Overall, approximately 30 percent of the patients developed dementia. After taking into account other factors associated with dementia, the incidence of dementia among statin users was the same as for patients who were not using statins.

Bottom Line: In this prospective observational study, patients older than 65 years who were taking statins developed dementia at the same rate as those who were not using statins. (Level of Evidence: 2b)