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Good Cholesterol and Alzheimer’s Disease: New Insights from Recent Study

Cholesterol, specifically high-density lipoprotein (HDL), is often referred to as “good” cholesterol due to its essential role in health. While it is well understood that HDL helps protect the cardiovascular system, researchers are beginning to explore its potential impact on the brain, particularly in relation to Alzheimer’s disease. A recent study suggests that higher levels of small HDL particles in the cerebrospinal fluid (CSF) might be associated with a reduced risk of Alzheimer’s disease (Alzheimer’s & Dementia, 2025).

Understanding Alzheimer’s Disease

Alzheimer’s disease is a progressive neurological disorder that primarily affects older adults, leading to a decline in cognitive functions such as memory, language, and decision-making. It is the most common cause of dementia and is characterized by the accumulation of specific proteins, such as amyloid plaques and tau tangles, in the brain. These abnormal proteins disrupt communication between neurons, eventually leading to the death of brain cells (Alzheimer’s Association, 2025). Currently, there is no cure for Alzheimer’s, and researchers are focused on understanding its underlying causes and developing effective treatments.

What is “Good” Cholesterol?

Cholesterol is a fatty substance that the body needs to function properly. It is used to make hormones, digest food, and build new cells. Cholesterol can either be produced by the liver or obtained from certain foods. There are two main types of cholesterol in the body: low-density lipoprotein (LDL), often referred to as "bad" cholesterol, and high-density lipoprotein (HDL), known as "good" cholesterol. LDL can build up in the arteries, leading to cardiovascular diseases, while HDL helps carry excess cholesterol back to the liver, where it is processed and removed (American Heart Association, 2025). Recent research is also exploring how HDL levels affect brain health, particularly in the context of Alzheimer’s disease.

The Study: HDL and Alzheimer’s Disease

A recent study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association examined the potential link between small HDL particles in the cerebrospinal fluid and the risk of developing Alzheimer’s disease. The study involved 180 participants aged 60 and older who were part of the University of Southern California (USC) Alzheimer Disease Research Center (ADRC) and the Huntington Memorial Research Institute (HMRI) Aging Program.

The researchers assessed participants’ cognitive functions using various cognitive tests and analyzed cerebrospinal fluid (CSF) and plasma samples. They also looked for the presence of the APOE ε4 gene, a well-known genetic risk factor for Alzheimer’s disease (Alzheimer's Association, 2025). The findings revealed that higher levels of small HDL particles in the CSF were associated with better cognitive function, even after controlling for factors such as APOE ε4 status, age, sex, and education (Alzheimer’s & Dementia, 2025).

Study author Hussein Yassine, M.D., highlighted the significance of these findings, noting that the discovery of lipid particles like HDL in the blood led to significant advances in cardiovascular disease treatments. He emphasized that measuring HDL particles in CSF provides a new insight into the potential relationship between cholesterol and brain health. He added, "Greater levels of small HDL correlate with better performance on cognitive measures. Our next step is to understand what promotes the formation of these small HDL particles in the brain" (Yassine, 2025).

Potential Implications for Alzheimer’s Treatment

This research opens the door to potential new approaches in Alzheimer's treatment. By understanding how small HDL particles function in the brain, researchers may be able to develop therapies that increase the levels of these protective particles and slow the progression of cognitive decline in Alzheimer's patients. However, more research is needed to confirm these findings and determine how these small HDL particles can be manipulated for therapeutic purposes (Alzheimer’s Association, 2025).

Study Limitations and Future Research

While the study's results are promising, the authors acknowledge several limitations. One key limitation is the difficulty in identifying which subtypes of small HDL particles have protective properties, as there are many different types of HDL. The researchers also emphasize that their study cannot establish a causal relationship between small HDL levels and Alzheimer’s disease risk. Further research is necessary to understand the interactions between HDL in the brain and in the bloodstream and to determine whether increasing HDL levels could prevent or delay the onset of Alzheimer’s disease.

The small sample size of the study also limits the generalizability of the results. Future studies could include larger sample sizes and longer follow-up periods to better understand the potential role of small HDL particles in preventing or delaying Alzheimer's disease. Percy Griffin, Ph.D., Director of Scientific Engagement at the Alzheimer’s Association, noted that the study contributes to the growing body of research on cerebrospinal fluid biomarkers. He stated, "These findings on small HDL particles are intriguing and may inform the development of biomarkers that can help predict the progression of Alzheimer’s disease" (Griffin, 2025).

Conclusion

While the link between small HDL particles and Alzheimer’s disease remains under investigation, the study provides an exciting new direction for research on the potential role of cholesterol in brain health. Understanding how HDL impacts the brain could eventually lead to innovative treatments that slow or prevent the cognitive decline associated with Alzheimer’s disease. However, more research is necessary to confirm these findings and explore how they can be translated into clinical applications.

References

• American Heart Association. (2025). Cholesterol. Retrieved from: https://www.heart.org/en/health-topics/cholesterol
• Alzheimer’s Association. (2025). Alzheimer's Disease Facts and Figures. Retrieved from :  https://www.alz.org/alzheimers-dementia/facts-figures
• Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association. (2025). HDL particles in cerebrospinal fluid and Alzheimer’s disease risk. Retrieved from: https://www.journals.elsevier.com/alzheimers-and-dementia

Griffin, P. (2025). Research director statement on small HDL particles and Alzheimer's disease. Alzheimer's Association.

Yassine, H. (2025). Study on small HDL particles in cerebrospinal fluid. Medical News Today.