Older patients who take statins may be at lower risk of developing dementia, according to findings from a prospective cohort study.

Statin users were 44% less likely to develop dementia and cognitive impairment than nonusers after controlling for other factors (P=0.010), reported Mary N. Haan, Dr.P.H., of the University of Michigan here, and colleagues in the July 29 issue of Neurology.

However, the findings were not enough to suggest that patients should take a statin unless necessary for other health reasons, the investigators cautioned.

Although these findings add evidence in favor of statins for cognitive outcomes, this area of research has been controversial with little agreement between studies, the researchers said.

At baseline, statin users and nonusers were similar, except that statin users were slightly younger, more educated, and more likely to have been born in the U.S. and covered by medical insurance.

Statin users were also more likely to have a history of diabetes and higher mean baseline cognitive scores on the Modified Mini-Mental State Examination.

During more than five years of follow-up, 130 participants developed dementia or cognitive impairment without dementia.

Of the 82 patients with dementia, 48% had possible or probable Alzheimer's disease, 23% had undetermined etiology, 13% had ischemic vascular dementia, and 13% had mixed Alzheimer's or vascular dementia.

Statin users had a 43% lower rate of dementia and non-dementia cognitive impairment than nonusers (hazard ratio 0.577, 95% confidence interval 0.376 to 0.886, P=0.012).

After controlling for baseline diabetes and stroke, statins remained associated with a 48% lower rate of dementia and non-dementia cognitive impairment (HR 0.518, 95% CI 0.336 to 0.797, P=0.003).

Further adjustment for education, smoking status, and apolipoprotein E (APOE-e4) genotype attenuated the association only slightly to a 44% lower risk compared with nonusers (HR 0.564, 95% CI 0.365 to 0.872, P=0.010).

The protective effect of statins on dementia held for both high functioning individuals with above-average cognitive scores on the Modified Mini-Mental State Examination (HR 0.546, 95% CI 0.327 to 0.912) and those with below average scores (HR 0.444, 95% CI 0.200 to 0.988).

The researchers cautioned that the findings may have been biased by differential loss to follow-up, indication bias, or competing risks.

However, they noted that statin use didn't appear to have an impact on survival (HR 0.92, 95% CI 0.69 to 1.20).


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