High LDL (bad) cholesterol levels are linked to amyloid plaque deposits, a signature characteristic of Alzheimer’s disease. On the other hand, high levels of ‘good’ HDL cholesterol and low levels of LDL cholesterol have been found to correlate with lower amyloid plaque deposits in the brain.
Lead study author Bruce Reed 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. 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 correlation between the risk of Alzheimer’s disease and elevated bad cholesterol levels has been known for quite some time, but this is the first study to specifically link cholesterol with amyloid plaque buildup.
Charles DeCarli, author of the study, added, “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. You have to get the HDL up and the LDL down.” He noted that these findings are a real wake-up call, reinforcing the importance of maintaining healthy cholesterol levels extending beyond just the heart health.
The study was conducted on 74 males and females over the age of 70. There were participants with mild dementia, with normal cognitive function, and with mild cognitive impairment.
The researchers observed amyloid plaque buildup through PET scans. Higher LDL and lower HDL cholesterol levels were associated with a greater amyloid plaque buildup in the brain. The mechanisms behind this association are still unknown.
Reed added, “This study provides a reason to certainly continue cholesterol treatment in people who are developing memory loss, regardless of concerns regarding their cardiovascular health. It also suggests a method of lowering amyloid levels in people who are middle aged, when such buildup is just starting. 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.”
There are numerous studies that suggest an association between cholesterol and Alzheimer’s disease. Understanding this link is important for developing better strategies to reduce the risk of Alzheimer’s disease. The researchers have identified a gene known as APOE4 that increases the risk of Alzheimer’s disease and impacts the processing of cholesterol in the body.
Scientists are hopeful that further research into the nature of APOE4 could render greater insight on the possible role that cholesterol plays in the development of Alzheimer’s disease.
Past studies have suggested that statins may also increase the risk of short-term cognitive impairment, as some patients on this medication report memory loss and confusion. However, a large meta-analysis study found that patients taking statins actually had a 29 percent lower risk of developing dementia, once again reaffirming that low LDL can protect a person’s brain against Alzheimer’s disease.
More research is required to further explore the association between Alzheimer’s disease and cholesterol.