'Bad' cholesterol may lead to Alzheimer's: study

High levels of 'bad' cholesterol are linked to one of the key brain signatures of Alzheimer's disease, a new study has warned.
High levels of "good" cholesterol and low levels of "bad" cholesterol are correlated with lower levels of the amyloid plaque deposition in the brain that is a hallmark of Alzheimer's disease, researchers have found.
The pattern mirrors the relationship between good and bad cholesterol in cardiovascular disease, researchers said.
"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," said Bruce Reed, lead study author from the University of California, Davis.

The relationship between elevated cholesterol and increased risk of Alzheimer's disease has been known for some time, but the current study is the first to specifically link cholesterol to amyloid deposits in living human study participants, Reed said.
"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.

"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," Charles DeCarli, director of the Alzheimer's Disease Center.

"You have to get the HDL up and the LDL down," said DeCarli.
The study was conducted in 74 diverse male and female individuals 70 years and older. They included three individuals with mild dementia, 33 who were cognitively normal and 38 who had mild cognitive impairment.
Higher fasting levels of LDL and lower levels of HDL both were associated with greater brain amyloid - a first-time finding linking cholesterol fractions in the blood and amyloid deposition in the brain.
"This study provides a reason to certainly continue cholesterol treatment in people who are developing memory loss regardless of concerns regarding their cardiovascular health," said Reed.

"It also suggests a method of lowering amyloid levels in people who are middle aged, when such build-up is just starting," Reed 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," he said.