In two studies of older people, statin use was not associated with 
dementia diagnoses.

Several cross-sectional and case-control studies have suggested that 
statins protect against development of dementia. However, prospective 
studies are better suited to examine this relation.

In one study, researchers prospectively followed more than 4000 
nondemented residents of a Utah county (age, ≥65). At 3-year follow-
up, 185 cases of dementia were diagnosed. After adjustment for 
potential confounders, statin use at baseline or at follow-up was not 
associated with reduced risk for incident dementia or Alzheimer disease.

In another study, researchers prospectively followed more than 2000 
nondemented people in a Seattle HMO (age, ≥65) for about 7 years; 312 
developed dementia during this interval. As in the Utah study, 
multivariate analyses failed to reveal any association between statin 
use and incident dementia or Alzheimer disease. Even patients with 
long durations of statin use and those who used high doses did not 
experience reduced risk for dementia.

COMMENT

The findings from these prospective studies cast some doubt on the 
idea that statins prevent dementia. Supporting these results are two 
large randomized trials (lasting 5 and 3 years) in which researchers 
observed no differences in cognitive function between statin and 
placebo groups (Journal Watch Jul 30 2002 and Journal Watch Jan 7 
2003). The possibility remains that long-term statin exposure, started 
early in life, confers some protection against cognitive decline.

Allan S. Brett, MD reviewing Zandi PP et al. Arch Gen Psychiatry 2005 
Feb. Li G et al. Neurology 2004 Nov 9.