Unhealthy cholesterol levels are linked to one of the key brain signatures of Alzheimer’s disease, scientists have learned.
Relative amounts of good and bad cholesterol in the blood influence the build-up of harmful protein deposits in the brain called beta amyloid plaques, a study found.
The discovery may explain the well-known correlation between raised cholesterol and an increased risk of Alzheimer’s.
Experts draw a sharp distinction between good cholesterol, or high density lipoprotein (HDL) and its evil twin – low density lipoprotein (LDL).
While high levels of LDL can lead to narrowed arteries and heart disease, HDL is protective.
The new US research suggests that the effects the two kinds of cholesterol have on the heart may be mirrored in the brain.
“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 study leader professor Bruce Reed, from the University of California at Davis.
“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.”
The scientists looked at 74 men and women aged 70 and over recruited from stroke clinics, support groups, senior citizens’ facilities and the UC Davis Alzheimer’s Disease Center.
Three participants were suffering from mild dementia, 38 had mild cognitive impairment – a non-serious loss of mental faculties – and 33 had no memory or thinking problems.
All had their brains scanned using a tracer chemical that binds with amyloid plaques so that they show up on the images.
Higher fasting levels of LDL and lower levels of HDL were both associated with more amyloid in the brain, according to the findings published online in the journal JAMA Neurology.
“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 professor Reed, associate director of the Alzheimer’s Disease Center.