Having higher levels of "good cholesterol" and less of the bad kind could significantly lower the concentrations of amyloid plaque in the brain, which has a high correlation with Alzheimer's disease.
"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," Bruce Reed, lead study author and associate director of the UC Davis Alzheimer's Disease Center said 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," he said.
This was the first study to show a solid correlation between cholesterol and amyloid deposits, although the link has been suspected in the past.
An HDL cholesterol level of 60 mg/dl ("milligrams (mg) of cholesterol per deciliter (dL) of blood") or higher is suggested in the U.S. Levels of LDL cholesterol should be 70 mg/dL or lower.
"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. "You have to get the HDL up and the LDL down."
The research team analyzed 74 study subjects over the age of 70 to make their findings. Thirty-three of the participants were mentally healthy; 38 suffered from "mild cognitive impairment"; and three had mild dementia. The team was able to find a link between the patients' cholesterol levels and their plaque levels.
"This study provides a reason to certainly continue cholesterol treatment in people who are developing memory loss, regardless of concerns regarding their cardiovascular health," Reed said.
"It also suggests a method of lowering amyloid levels in people who are middle aged, when such build-up is just starting," he said. "If modifying cholesterol levels in the brain early in life turns out to reduce amyloid deposits late in life, we could potentially make a significant difference in reducing the prevalence of Alzheimer's, a goal of an enormous amount of research and drug development effort."
