NEW YORK (Reuters Health) – Older individuals taking lipid-lowering medications have a lower risk of dementia, particularly Alzheimer's disease, compared with those not receiving these drugs, after accounting for confounders for a healthy lifestyle.
The finding comes from a Canadian population-based study, appearing in the February issue of the Archives of Neurology. In a second report in the same journal issue, German researchers find that treatment with simvastatin affects cholesterol metabolism in the brain, which they believe might be a mechanism by which the long-term use of statins reduced the incidence of Alzheimer's disease.
In the first report, Dr. Kenneth Rockwood, from Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia, and colleagues collected data on 2305 Canadians, 65 years of age and older, who participated in the Canadian Study of Health and Aging.
From this cohort, the researchers compared 492 people who developed dementia between the first and second waves of the study (326 with Alzheimer's disease), with 823 control subjects.
Use of lipid-lowering agents "was not associated with factors indicating a healthy lifestyle," the investigators found. The risk of Alzheimer's disease was reduced in those under 80 years of age who were receiving statins or any lipid-lowering agent (odds ratio 0.26), and this effect remained after adjusting for sex, education, and self-reported health status.
"These data suggest that lipid-lowering agents may have a role in protecting against the expression of dementia in elderly people," Dr. Rockwood and colleagues comment.
In the second study, Dr. Klaus von Bergmann, from the University of Bonn, and associates treated 18 hypercholesterolemic patients with simvastatin 80 mg/day for 24 weeks. Levels of 24S-hydroxycholesterol (cerebrosterol), which "is important for cerebral cholesterol homeostasis," were assessed at baseline and at 6 and 24 weeks.
Total plasma cholesterol was reduced by 36% from baseline after 6 weeks of treatment and by 35% after 24 weeks of treatment (p < 0.001). Plasma 24S-hydroxycholesterol were also reduced during simvastatin therapy (45% at 6 weeks and 53% at 24 weeks, p < 0.001).
"The results of the present study show for the first time that simvastatin apparently affects cholesterol metabolism in the human brain," Dr. von Bergmann and colleagues comment. The reduction in cholesterol turnover in the brain "might provide the pharmacological basis for a possible mechanism of action of statins in preventing Alzheimer's disease and vascular dementia."