High Levels Of Good Cholesterol May Increase Dementia Risk

Very high HDL cholesterol—often called “good cholesterol”—was associated with a higher dementia risk in a study of 18,668 mostly healthy older adults. HDL-C over 80 mg/dL (2.07 mmol/L) was linked to a 27% higher risk overall and a 42% higher risk among people aged 75 or older, but the observational findings do not show causation.  

High Levels Of Good Cholesterol May Increase Dementia Risk
Medically reviewed

Dr. Chrysoula I. Liakou MD, PhD Google Scholar LinkedIn

Internal Medicine Specialist
Cancer Immunology Researcher

High Levels Of "Good Cholesterol" May Increase Dementia Risk

  • There is a recent study that suggests older adults with high levels of HDL-C (known as "good cholesterol") may have an increased risk of dementia.

  • One possibility is that HDL cholesterol acts differently in the brain than in the rest of the body, leading to the stiffening of blood vessels. This may raise the risk of stroke.

  • The study found that one's diet did not cause high levels of HDL-C associated with dementia risk but rather a metabolic disorder and was relatively uncommon.


A recent study has found that older adults who have high levels of HDL-C, also known as 'good cholesterol,' may face an increased risk of developing dementia.


Researchers clarified that the risk associated with very high levels of HDL-C was not related to diet and was relatively uncommon. Instead, it was more likely that it pointed to an underlying metabolic disorder.


A group of scientists conducted a study on 18,668 elderly individuals who were predominantly over 70 and in good health. Over a period averaging 6.3 years of observation, the researchers discovered that participants with exceptionally high levels of HDL-C (>80 mg/dL or >2.07 mmol/L) at the outset of the study had a 27% increased likelihood of developing dementia in comparison to those with ideal HDL-C levels (for males: 40 to 60 mg/dL or 1.03–1.55 mmol/L; for females: 50 to 60 mg/dL or 1.55–2.07 mmol/L).


There was a 42% increased risk of dementia observed in individuals aged 75 years and above who had suboptimal HDL cholesterol levels as compared to those with optimal levels.


The study included 2,709 participants who had very high HDL cholesterol levels at the beginning, among whom 38 cases of dementia were observed in those aged below 75 years, and 101 patients were observed in those aged 75 years and above.



Good Cholesterol Vs. Bad Cholesterol


Cholesterol is often simplified as "good" and "bad," but this doesn't capture the whole picture. HDL cholesterol is usually called "good" because it helps move cholesterol from the bloodstream to the liver.


In contrast, LDL cholesterol is termed "bad" because it can build up in artery walls, causing plaque formation and atherosclerosis. However, recent research shows that HDL's role is more complicated than being "good."


Understanding cholesterol is like understanding complex biology. LDL cholesterol is essential for transporting cholesterol from the liver to various body organs through the bloodstream. Still, it's labelled "bad" because it's the primary cholesterol found in plaques that can clog arteries, leading to blockages, blood clots, and inflammation and increasing the risk of stroke and coronary disease.


On the other hand, HDL cholesterol is considered "good" because it helps move cholesterol from the arteries back to the liver, preventing plaque buildup. LDL and HDL cholesterol are necessary for the body to function appropriately, highlighting the importance of maintaining a balanced ratio.



How Too Much ‘Good Cholesterol’ Affects Dementia Risk


Right now, we don't have solid proof that HDL cholesterol directly causes dementia, even though some studies suggest a possible link. This ongoing research is making us ask more questions and explore this connection further.


One reason for this possible link is that HDL cholesterol behaves differently in the brain compared to the rest of the body. In the brain, it might make blood vessels stiff, which could raise the risk of stroke. It could also cause inflammation in the brain, which might be connected to certain types of dementia. But it's important to remember that high levels of HDL might not act the same way as usual levels.


In general, having unusual levels of substances, even if they're considered "good," can lead to health problems. Staying balanced and moderate in everything is usually the best way to stay healthy. HDL mainly carries cholesterol, which the brain needs. When HDL levels get incredibly high, it might change how cholesterol works in the brain. And HDL may do more for brain health than just dealing with cholesterol.


High HDL-C Levels Are Also Linked To Metabolic Disorders


The study found that having very high levels of HDL cholesterol (HDL-C) was linked to a higher risk of dementia. These high levels weren't common and weren't because of diet. Instead, they might indicate a metabolic problem.


The study showed this link when HDL levels were above 80 mg/dl, higher than usual. However, it's essential to know that HDL levels can vary significantly from person to person. While your lifestyle can affect your HDL levels, genetics also play a big part.


Genetic changes can increase your HDL levels, as the study showed. Even though the study tried to account for these genetic changes, we still don't understand how genetics, HDL levels, and dementia risk are connected. These genetic differences might affect both HDL levels and the risk of dementia, but we need more research to figure it out.


Limitations Of This Study


The main limitation of this study is related to its demographics. The study primarily involved relatively healthy white participants. This raises questions about the applicability of the findings to a more diverse population. Generalizing the results to most patient groups in the United States is challenging.


Other limitations to consider include:

  • Lack Of Diversity: Only a tiny % of participants (9%) were non-white. Dementia risk factors can vary significantly among different racial and ethnic groups.

  • Genetic Factors: The genome analysis used in the study couldn't identify if there might be a single genetic factor contributing to both extremely high HDL levels and dementia.

  • Absence Of Dementia Biomarkers: The study didn't include biomarkers for dementia, making it difficult to determine the specific type of dementia (vascular dementia, Alzheimer's disease, etc.) and gain better insight into the role of HDL cholesterol in these conditions.


For assistance and guidance regarding your health concerns, consider consulting with Mobi Doctor for expert advice and support through telemedicine services.



Very High HDL Cholesterol and Dementia Risk FAQs

Very high HDL cholesterol was associated with increased dementia risk in this study, particularly among older adults. Participants with HDL-C over 80 mg/dL had a 27% higher relative risk than those in the study’s comparison range. This does not mean most people with high HDL develop dementia, and the result cannot prove that HDL caused the condition.

The researchers classified HDL-C over 80 mg/dL, or 2.07 mmol/L, as very high. The comparison ranges reported were 40–60 mg/dL for men and 50–60 mg/dL for women. These were categories used in the research, not a standalone diagnostic or treatment threshold for an individual patient.

No causal link between very high HDL cholesterol and dementia has been established. The study was observational, so it could detect an association but could not show that excess HDL directly produces cognitive decline. Genetic, metabolic or vascular factors may influence both HDL levels and dementia risk, and further research is needed.

Researchers have proposed several possible explanations, but none has been confirmed. At extremely high concentrations, HDL particles may function differently, potentially contributing to blood-vessel stiffness, stroke risk or inflammatory changes in the brain. Changes in HDL structure and cholesterol transport could also affect brain health, although the biological pathway remains uncertain.

HDL is beneficial in normal physiological balance, but calling it “good cholesterol” oversimplifies its role. HDL generally transports cholesterol from the arteries back to the liver, while LDL can accumulate in artery walls and contribute to plaque. The study suggests that extremely high HDL may not function in the same way as levels within a typical range.

Unusually high HDL cholesterol may reflect more than diet alone. In this study, the very high levels associated with dementia risk were uncommon and were considered more likely to indicate an underlying metabolic disorder; genetic variants may also contribute. Lifestyle affects HDL, but it may not fully explain an extreme result.

The strongest association appeared among participants aged 75 or older with very high HDL-C. Their dementia risk was 42% higher relative to participants in the comparison range. This is a relative-risk figure within the study population; it does not mean that 42% of older people with very high HDL developed dementia.

The study mainly involved relatively healthy older adults and included limited racial and ethnic diversity, so the findings may not apply equally to all populations. It also lacked dementia biomarkers to distinguish Alzheimer’s disease, vascular dementia or other causes, and the genetic analysis could not rule out a shared factor affecting both HDL and dementia risk.

An HDL result over 80 mg/dL should not be treated as proof of dementia risk. The study threshold described an association in mostly healthy older adults, not a diagnostic or treatment cutoff. A clinician can interpret the result alongside age, the wider lipid profile, medical history and possible metabolic or genetic factors.


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