A new study for the first time links cholesterol not just to heart disease but to the buildup of brain plaque known to cause Alzheimer’s. In an optimal tandem, higher levels of good cholesterol coupled with lower levels of bad cholesterol were correlated to lower levels of amyloid plaque deposits in the brain.

Although investigators at the University of California at Davis say science has long known of the link between cholesterol and Alzheimer’s risk, the study establishes for the first time a link between cholesterol and plaque deposits in living patients.

"Our study shows that both higher levels of HDL — good — and lower levels of LDL — bad — cholesterol in the bloodstream are associated with lower levels of amyloid plaque deposits in the brain," lead investigator Bruce Reed, said Monday in a statement. "Unhealthy patterns of cholesterol could be directly causing the higher levels of amyloid known to contribute to Alzheimer's, in the same way that such patterns promote heart disease.”

For patients with a high risk of heart disease, experts recommend a ratio of good HDL cholesterol of 60 mg/dl or higher, with levels of bad LDL cholesterol below 70 mg/dl or lower.

Investigator Charles DeCarli, director of the university’s Alzheimer’s Disease Center, said the study shows people may influence brain health later in life by controlling blood pressure and regulating diet to influence cholesterol levels good and bad. "If you have an LDL above 100 or an HDL that is less than 40, even if you're taking a statin drug, you want to make sure that you are getting those numbers into alignment," DeCarli said in the statement. "You have to get the HDL up and the LDL down."

In the study, investigators followed 74 elderly men and women who were recruited for study from stroke clinics, support groups, and senior facilities. Of the over-70 group, three suffered mild dementia, while another 38 experienced mild cognitive impairment. The other 33 were deemed cognitively typical for their ages. Using a tracer that binds with amyloid plaques in the brain, the investigators were then able to use imaging technology to search for Alzheimer’s in the living brain.

Among fasting patients, higher levels of bad cholesterol with lower levels of the good correlated with greater amounts of brain plaque. Future study would determine how cholesterol influences the development of brain plaque and, therefore, the degenerating effects of Alzheimer’s disease.

The new findings may cause some doctors to question recent guidelines issued by the American College of Cardiology, the American Heart Association, and the National Heart, Lung, and Blood Institute, which recently recommended the scuttling of national cholesterol guidelines.

"This study provides a reason to certainly continue cholesterol treatment in people who are developing memory loss regardless of concerns regarding their cardiovascular health," he said. "It also suggests a method of lowering amyloid levels in people who are middle aged, when such buildup is just starting.”

Next, investigators plan to determine whether early cholesterol interventions would stymie the development of brain plaque later in life.

Source: Reed, Bruce. Associations Between Serum Cholesterol Levels and Cerebral Amyloidosis. JAMA Neurology. 2013.