"Good" cholesterol may reduce the risk of Alzheimer's disease

The good cholesterol or high density lipoprotein (HDL) is essential for good health. Yet the impact of HDL on the brain is not fully understood. Alzheimer’s disease is a disorder that affects people’s ability to think and function in daily life. Researchers are still working to develop treatments and understand this disease. A recent study suggests that higher levels of small high-density lipoproteins may reduce the risk of Alzheimer’s disease.

Alzheimer’s disease is a debilitating condition that primarily affects older people. People who have it can lose their memory and become unable to perform daily living tasks. Currently, the disease is incurable. Researchers are still trying to understand how the disease develops, how to prevent it, and how best to treat it. A recent study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association sheds new light. Researchers have studied the link between small HDL or “good” cholesterol in the cerebrospinal fluid and the risk of Alzheimer’s disease. The results suggest that higher levels of small HDL were associated with a lower risk of developing Alzheimer’s disease.

What is “good” cholesterol?

Cholesterol is a substance that the body needs. For example, the body uses cholesterol to make certain hormones, properly digest food, and make new cells. The body makes cholesterol, but people can also get it from food sources.

Cholesterol exists in the body in two main forms: low density lipoproteins (LDL) and high density lipoproteins (HDL). LDL can build up in the bloodstream and increase the risk of stroke and heart attack. It is therefore essential that your LDL level is not too high.
The body’s HDL or “good” cholesterol helps bring cholesterol back to the liver so that it can break it down. But HDL may impact other areas of health in ways that researchers don’t fully understand. For example, researchers are still trying to understand how HDL levels affect the brain. The study authors note that the HDL present in the brain is slightly different from the HDL present in the rest of the body.

What is Alzheimer’s disease?

Alzheimer’s disease is a disease that affects the brain and usually occurs in adults over the age of 60. It affects the nerves in the brain and is linked to the buildup of specific proteins in the brain. Eventually, neurons in the brain die and lose their ability to communicate with other brain cells.
Because of this damage, people with Alzheimer’s disease have problems with memory, language, and decision-making. It can be debilitating, and people with Alzheimer’s disease often slowly lose their ability to function independently.
Research continues into the causes of Alzheimer’s disease and how best to develop treatments.

Good cholesterol and Alzheimer’s disease

The study in question involved 180 participants aged 60 or older. Participants took part in the study through the Alzheimer’s Disease Research Center (ADRC) at the University of Southern California (USC) and the Huntington Memorial Research Institute (HMRI) Aging Program. The researchers examined the cognitive functions of the participants using various cognitive tests. They took samples of cerebrospinal fluid (CSF), the fluid that surrounds the brain and spinal cord, and plasma from the participants and isolated their DNA. The researchers searched for the APOE ε4 gene in DNA, a potential risk factor for Alzheimer’s disease.

The researchers then looked at the levels of small HDL particles in the CSF. They found that higher levels of these small HDL particles were associated with better cognitive function in participants. They found that this result was the same even after taking into account the APOE ε4 gene, age, sex and level of education. The results of the study could lead to the development of new treatments for Alzheimer’s disease.

The authors conclude that “the discovery of lipid particles (LDL, HDL) in the blood has led to several advances in drug discovery for the treatment and prevention of cardiovascular disease. Here, for the first time, we measure HDL particles in cerebrospinal fluid as a surrogate for brain HDL and find that higher levels of small HDL are correlated with better performance in cognitive measures. Now that we have this biomarker, our next step is to determine what promotes the formation of these small HDL particles in the brain. These new discoveries could then lead to a new list of drugs in our fight against Alzheimer’s disease. »

Limits of the study and further research

The study authors pointed out that their study had several limitations. First, it is difficult to identify which of these particles has the protective properties because there are many subtypes of small HDLs. They acknowledge that further research is needed to understand the interactions and differences between HDL present in the brain and those in the general circulation.

The researchers also acknowledge that the study findings cannot be generalized and that the study does not show causation. Further research could examine whether HDL levels can predict the development of cognitive problems and whether increasing HDL levels could help prevent Alzheimer’s disease. The researchers note that future studies could include more participants and have longer-term follow-ups.

This work is interesting and adds to the growing body of research examining different species in cerebrospinal fluid. These findings on small high-density lipoprotein particles are intriguing and may contribute to the development of biomarkers that can help predict how quickly people will progress to Alzheimer’s disease. However, the sample size is quite small and further research is needed.