A new study led by Monash University has found that having abnormally high levels of HDL cholesterol—often called “good cholesterol”—may increase the risk of dementia in older adults.
The research, published in The Lancet Regional Health—Western Pacific, suggests that very high levels of this cholesterol might not always be beneficial, especially in people aged 75 and older.
HDL cholesterol (HDL-C) is known for helping to remove bad cholesterol from the bloodstream, reducing the risk of heart disease. However, researchers found that when HDL-C levels were extremely high, it was linked to a greater likelihood of developing dementia.
Importantly, these high levels were not related to diet but were likely caused by an underlying metabolic condition.
What the Study Found
The study analyzed data from one of the largest research projects on aging, called the ASPREE study. It included 18,668 older adults, most of whom were over 70 and initially healthy, with no diagnosed heart disease, dementia, or serious illnesses when they joined the study.
Over an average period of 6.3 years, researchers observed that participants with very high HDL-C levels—above 80 mg/dL (2.07 mmol/L)—had a 27% higher risk of dementia compared to those with optimal HDL-C levels. The risk was even greater in those aged 75 and older, with a 42% higher chance of developing dementia compared to those with optimal HDL-C levels.
For reference, the optimal HDL-C levels for heart health are:
- Men: 40 to 60 mg/dL (1.03–1.55 mmol/L)
- Women: 50 to 60 mg/dL (1.55–2.07 mmol/L)
Among the study participants, 2,709 people had very high HDL-C levels when they joined the study. During the follow-up period, 38 cases of dementia were recorded in participants under 75 with very high HDL-C, while 101 cases were recorded in those aged 75 and older with very high levels.
What Does This Mean?
Dr. Monira Hussain, the lead researcher from Monash University’s School of Public Health and Preventive Medicine, said that while HDL-C is generally seen as beneficial for heart health, these findings suggest that extremely high levels may have unexpected effects on brain health.
However, more research is needed to understand why very high HDL-C levels might contribute to dementia risk.
“This study helps us learn more about the connection between cholesterol and brain health,” Dr. Hussain explained. “It may be useful to consider very high HDL cholesterol levels when predicting a person’s risk of dementia in the future.”
About the ASPREE Study
The research is part of the Aspirin in Reducing Events in the Elderly (ASPREE) study, a major international trial that began between 2010 and 2014. The study recruited 16,703 participants aged 70 and older from Australia and 2,411 participants aged 65 and older from the US.
All participants were in good health at the start, with no history of cardiovascular disease, dementia, or severe illness. The study originally examined the effects of daily aspirin use in older adults but has continued as an observational study (ASPREE-XT) to track long-term health outcomes.
Analysis of the Findings
This research challenges the common belief that more HDL cholesterol is always better. While moderate levels of HDL-C help protect the heart, excessively high levels may signal underlying health problems that could affect brain function.
Scientists still do not fully understand why this happens, but possible explanations include changes in how cholesterol is processed in the body or its effect on blood circulation in the brain.
These findings could help doctors identify older adults who may be at greater risk of dementia based on their cholesterol levels. However, more studies are needed to confirm the results and explore whether lowering extremely high HDL-C levels could reduce the risk of dementia.
For now, the study highlights the importance of balanced cholesterol levels rather than simply aiming for the highest possible HDL-C. Future research may provide more insights into how cholesterol affects brain health and whether doctors should include HDL-C levels in dementia risk assessments.
If you care about dementia, please read studies about dietary strategies to ward off dementia, and how omega-3 fatty acids fuel your mind.
For more health information, please see recent studies about Choline deficiency linked to Alzheimer’s disease, and what to eat (and avoid) for dementia prevention.
The research findings can be found in The Lancet Regional Health—Western Pacific.
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