Both good and bad cholesterol may be associated with dementia risks, a new study finds.

van Vliet P. Cholesterol and late-life cognitive decline. Journal of Alzheimer’s Disease. 2012;30(s2). doi:10.3233/jad-2011-111028

 

Researchers from the University of California used electronic health records to examine the relationship between low-density lipoprotein cholesterol (LDL-C), or “bad” cholesterol, and high-density lipoprotein cholesterol (HDL-C), “good” cholesterol, in 184,367 participants.  Participants with low and high levels of LDL-C at the beginning of the study had increased risks of developing dementia by the end of the study. HDL-C was moderately associated with dementia risks. 

Study findings demonstrate a need for more research on cholesterol’s role in neurodegenerative diseases, including to what extent “good” cholesterol needs to be addressed to reduce dementia risks.

 

LDL cholesterol’s impact on dementia 

 

This isn’t the first study to look at LDL-C’s impact on dementia.

Based on prior research, James Giordano, PhD, MPhil, a researcher and professor of neurology and biochemistry at Georgetown University, says one way that LDL-C can increase inflammation in the body is through atherosclerosis. Atherosclerosis is a disease characterized by thickening or hardening of the arteries, which high LDL-C levels can influence. Atherosclerosis is known to reduce blood flow to the brain and can increase risks of vascular dementia in particular.

Johns Hopkins Medicine. Atherosclerosis.

National Institute on Aging. Abnormal cholesterol metabolism linked to dementia risk. July 15, 2021.

 

“LDL contributes directly to atherosclerosis, and atherosclerosis engages an inflammatory state and vice versa,” Dr. Giordano says.

High LDL-C levels can promote inflammation throughout the whole body (not just vascular cells), which “can be problematic to a number of organs, the brain being one of them,” Dr. Giordano adds.

Inflammation in the brain can increase risks for dementing effects like problems with cognition, instability, and emotion, among other undesirable consequences, he says. 

More research may be needed to confirm the exact mechanisms at play and what else is working to increase these risks. Further, more research could help doctors understand if LDL-C management could serve as a factor in dementia prevention in the future.

 

Wait, low cholesterol is bad, too?

 

Study researchers linked low and high LDL-C levels to increased dementia risk. While this seemingly counters the idea that lower cholesterol levels are healthier, it also reinforces fundamental wellness concepts championing balance over extremes.

“One of the things that this brings home is the argument against the extremes,” Dr. Giordano says. “Too high: no good. Too low: no good.”

Too-low cholesterol levels can negatively impact health in various ways, such as impacting our hormones and the brain.

van Vliet P. Cholesterol and late-life cognitive decline. Journal of Alzheimer’s Disease. 2012;30(s2). doi:10.3233/jad-2011-111028

 

 

HDL cholesterol’s impact on dementia 

 

The study found that HDL-C, also known as “good” cholesterol, was mostly associated with dementia risk. This connection has not been studied with as much vigor as LDL-C, and more studies will be needed to understand the link. 

With what we know so far, the connection is “vague and somewhat ambiguous,” Dr. Giordano says.

“HDL, the beneficial cholesterol, seems to have some effect on the predisposition and expression for dementia,” Dr. Giordano adds. “The question is whether or not HDL levels are an artifact of overall cholesterol metabolism, or whether HDL may also be influential to our brain’s micro inflammatory response.”

For now, the study highlights the importance of monitoring overall cholesterol levels, Dr. Giordano says.

“Certainly, it supports previous findings that low-density lipoprotein cholesterol is, in fact, the quote “bad” culprit that we thought it was,” he adds. “It also indicates that higher levels of overall cholesterol and or just elevations in high-density lipoprotein cholesterol can also have something of an influential effect.”

In some cases, doctors may want to be more vigilant when checking cholesterol levels in patients with family histories of dementia, as management could decrease their risks. Working one-on-one with each patient to address concerns of high cholesterol and/or cognitive decline can help you tailor advice and treatment to individuals.