“Association Found Between High and Low ‘Good’ Cholesterol Levels and Increased Dementia Risk, Reveals Large-Scale Study”
A recent study published in Neurology, the medical journal of the American Academy of Neurology, sheds light on the connection between high-density lipoprotein (HDL) cholesterol, often known as “good” cholesterol, and dementia risk in older adults. While the study doesn’t establish causation, it uncovers an association between both elevated and reduced HDL cholesterol levels and a slightly elevated risk of dementia.
Background and Significance:
Lead author Maria Glymour, ScD, from Boston University, highlights the importance of this research, stating, “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.” The extensive dataset allowed for precise estimates across the spectrum of cholesterol levels, including those with exceptionally high or low levels.
Study Details:
The study involved 184,367 participants from the Kaiser Permanente Northern California Health Plan, with an average age of 70, all of whom did not have dementia at the study’s outset. Over the course of the study, these individuals completed health behavior surveys and had their cholesterol levels measured approximately 2.5 times during routine healthcare visits in the subsequent two years. They were then monitored within the Kaiser healthcare system via electronic health records for an average of nine years, during which 25,214 participants developed dementia.
Findings on HDL Cholesterol and Dementia Risk:
The average HDL cholesterol level among participants was 53.7 milligrams per deciliter (mg/dL), with healthy levels considered to be above 40 mg/dL for males and above 50 mg/dL for females. Based on their HDL cholesterol levels, participants were categorized into five groups.
Surprisingly, individuals with the highest HDL cholesterol levels exhibited a 15% higher dementia risk compared to those in the middle group, while those with the lowest levels had a 7% higher risk of dementia compared to the middle group. Importantly, these findings were adjusted for other factors that could influence dementia risk, such as alcohol consumption, high blood pressure, cardiovascular disease, and diabetes.
Consideration of Other Risk Factors:
The study also examined low-density lipoprotein (LDL) cholesterol, often referred to as “bad” cholesterol, and its association with dementia risk. However, researchers found only a minor link between LDL cholesterol and dementia risk within the overall study cohort.
Maria Glymour emphasizes, “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. 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.”
Study Limitation and Support:
It’s worth noting that participants volunteered for the survey, which could introduce selection bias, potentially limiting the study’s generalizability to the broader population. This research received support from the National Institute on Aging and the National Institutes of Health.
Disclaimer: The views, suggestions, and opinions expressed here are the sole responsibility of the experts. No Genz Flash journalist was involved in the writing and production of this article.