Alzheimer's Tied to High Levels of Bad Cholesterol

Healthy levels of "good" and "bad" cholesterol aren't only important for staving off heart disease, but may also help prevent Alzheimer's by keeping a person's levels of amyloid plaque, a key marker of the disease, low, according to a new study led by researchers from the University of California, Davis.

"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 and associate director of the UC Davis Alzheimer's Disease Center.

That elevated cholesterol and an increased risk for Alzheimer's disease are linked is not itself news. Instead, the new study, published in the journal JAMA Neurology, is the first to link cholesterol to amyloid deposits in the brain of living humans.

The study included 74 participants age 70 and older, all of whom were recruited from stroke clinics, support groups, senior facilities and the Alzheimer's Disease Center in California. Three individuals suffered from mild dementia while 33 were considered cognitively normal. Thirty-eight had mild cognitive impairment.

Amyloid levels were determined using a tracer that binds with amyloid plaques. The participants' brains were then imaged using PET scans, with higher fasting levels of LDL and lower levels of HDL both associated with greater brain amyloid.

"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," Reed explained.

According to Charles DeCarli, co-author of the study and director of the Alzheimer's Disease Center, the paper should serve as an alarm to the millions of Americans with high cholesterol.

"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 Centers for Disease Control and Prevention estimates that some 71 million - or one in three - adults living in the United States have high LDL cholesterol, and that less than half receive treatment for it.