For many Americans, losing the ability to think and remember is the single biggest fear about growing older.
A new study published in the Archives of Neurology finds that women 65 and older who had high levels of cholesterol were more likely to have problems thinking clearly than those with healthy cholesterol levels.
Researchers now suggest that some women may have difficulty thinking clearly because what they eat causes high cholesterol.
"We found that indeed women with the higher cholesterol levels had significantly more problems with memory and thinking," says Dr. Elizabeth Barrett-Connor, lead author of the study and professor of family and preventive medicine at the University of California, San Diego.
Specifically, women with cholesterol levels of 235 or higher had difficulty with mental testing. A healthy cholesterol level is under 200.
The study also found that lowering total cholesterol was associated with a 50 percent reduction in the risk of "cognitive" or memory problems.
"Over the past several years, there's been increasing evidence that cholesterol is associated with alteration of thinking and functioning when you get older," says Dr. Steve DeKosky, director of Alzheimer's Disease Research Center of the University of Pittsburgh.
Some scientists suspect cholesterol damages the brain in much the same way it damages the heart: It collects on the walls of tiny blood vessels, making them narrower and reducing the flow of blood. And without enough blood, the brain can no longer function properly.
Researchers are now investigating not only the effect on the brain of high cholesterol, but also the impact of high blood pressure, diet and exercise — in other words, the same risk factors normally associated with the heart.
Until they learn more, some researchers say that maintaining a healthy heart may be just what's needed for a healthy brain.
The ABC News Medical Unit asked three experts to answer some questions to help people understand the study.
1. What is new about this study that we did not know before?
"Previous studies have already suggested a link between high cholesterol and an increased risk for Alzheimer's, but I don't think there has been enough public awareness of the strength of this link. Because if people have a chance to lower their risk for Alzheimer's simply by lowering cholesterol, that's very valuable information. Most people with high cholesterol probably don't have to take statins, but instead should try eating one less slice of pizza. Most people who don't have a family history of heart disease don't worry about their cholesterol. Well here is another reason to worry."
—Rudolph E. Tanzi, Ph.D., Director of Genetics and Aging Research Unit, Massachusetts General Hospital
2. Should post menopausal women start taking statin drugs to reduce their risk of Alzheimer's? If so, why, if not, why not?
"We must be really careful here People currently only go on statins if they meet the National Institutes of Health's criteria, that is, their cholesterol's are already so high that they need medication to lower them. There is no data about what would happen if people who had normal cholesterol would take statins. Anyone who does meet elevated cholesterol criteria for taking statins should be taking them already, unless they have a medical contraindication."
—Steven T. DeKosky, M.D., Director, Alzheimer's Disease Research Center, University of Pittsburgh