BY Jill Stein
From REUTERS NEWS SERVICE
April 17, 2002
DENVER (Reuters Health) - Cholesterol-lowering medications called statins may reduce the risk of Alzheimer's disease, investigators reported here Tuesday at the American Academy of Neurology's annual meeting.
Dr. Robert C. Green and colleagues at Boston University School of Medicine studied 2,581 people, 614 of whom were African-American. The researchers compared 912 persons with probable or definite Alzheimer's disease to 1,669 family members without the memory-robbing disorder. After taking into account a number of factors that can influence Alzheimer's risk, including age, sex, ethnic background, education and history of heart disease, stroke, and diabetes, they found that those who used cholesterol-lowering statin drugs were 79% less likely to have Alzheimer's than those who did not.
Treatment with other cholesterol-lowering medications was also associated with a decreased risk of Alzheimer's disease, but the results were not statistically significant.
Green told Reuters Health that his study does not prove that the reduction in Alzheimer's risk was due to statin use. For example, the findings might be explained if people who were more likely to develop Alzheimer's disease were also less likely to be prescribed statins, for some as yet undiscovered reason. Any clear link between statin use and Alzheimer's could only be determined through a prospective clinical trial--a study in which participants are followed over time.
"However, our study does bolster earlier reports suggesting that such a relationship exists, and, in addition, provides compelling evidence that a prospective clinical trial should be undertaken," he added.
Also, while the study did not look at mechanisms that might explain the favorable effect of statins on Alzheimer's risk, there are several possibilities, he said. For example, the cholesterol-lowering effect could be responsible, or the drugs could help prevent mini-strokes that damage the brain. Statins could also somehow affect the formation of the abnormal plaques that are characteristic of Alzheimer's disease.
Finally, Green emphasized that the study is "particularly notable" in that it is the largest trial to show a protective effect of statin medications against Alzheimer's as well as the first investigation to evaluate the effects of African-American ethnicity and Apo E gene. A variation of this gene, Apo E-e4, is known to increase Alzheimer's risk. In the study, a person's Apo E status did not affect the link between Alzheimer's risk and statin use.
While two earlier studies had suggested that statins helped protect against Alzheimer's, the results were limited by shortcomings in the trials' design, Green explained. For example, in both of the studies, the time relationship between statin use and the onset of dementia symptoms was not clear. Also, the earlier studies did not enroll African Americans, did not control for educational background and did not look at the effect of the type of Apo E gene people had.