HEALTH
High And Low Levels Of ‘Good’ Cholesterol Associated With Increased Risk Of Dementia, Study Finds
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High or low levels of so-called good high-density lipoprotein, or HDL, cholesterol is correlated with a small increased risk of dementia, according to a new study.
Researchers warned, however, that their study does not show high or low levels of HDL cholesterol cause dementia, it only shows an association.
The study, published Wednesday in the journal [Neurology](https://n.neurology.org/content/early/2023/10/04/WNL.0000000000207876), looked at 184,367 people from the Kaiser Permanente Northern California Health Plan, with an average age of 70, who did not have dementia at the beginning of the study.
Participants completed surveys on their health behaviors, and had their cholesterol measured during routine health care visits an average of 2.5 times over the course of two years. They were then followed via electronic health records for an average of another nine years.
Of those participants, 25,214 people developed dementia during the study period.
The average HDL cholesterol level was 53.7 milligrams per deciliter (mg/dL). Healthy levels are considered to be above 40 mg/dL for males and above 50 mg/dL for females.
According to the study, people with the highest levels of HDL cholesterol had a 15% higher rate of dementia compared to those in the middle group. Those with the lowest levels had a 7% higher rate of dementia compared to those in the middle group.
“Previous studies on this topic have been inconclusive and this study is especially informative because of the large number of participants and long follow-up,” said study co-author Maria Glymour of Boston University. “This information allowed us to study the links with dementia across the range of cholesterol levels and achieve precise estimates even for people with cholesterol levels that are quite high or quite low.”
Researchers accounted for other factors that can affect dementia risk, including alcohol use, high blood pressure, cardiovascular disease and diabetes.
They also found that bad low-density lipoprotein, or LDL, cholesterol was only slightly associated with dementia risk.
“The elevation in dementia risk with both high and low levels of HDL cholesterol was unexpected, but these increases are small, and their clinical significance is uncertain,” Glymour said. “In contrast, we found no association between LDL cholesterol and dementia risk in the overall study cohort. Our results add to evidence that HDL cholesterol has similarly complex associations with dementia as with heart disease and cancer.”
According to the Centers for Disease Control and Prevention, blood cholesterol is a waxy, fat-like substance made by the liver. Because the body makes all the blood cholesterol it needs to function, experts recommend people consume as little dietary cholesterol as possible, the agency said.
TMX contributed to this article.
