Cholesterol is a fatty substance that is present in all tissues of the human body and is necessary for the normal functioning of the body. It serves as a raw material for the membranes (walls) of cells and for the synthesis (manufacture) of hormones such as estrogens and androgens. High levels of total cholesterol mean more fat in the tissues and its accumulation in the arteries is associated with increased risk of cardiovascular disease.
A recent study by the University of Southern California (USC) found that “good” cholesterol can play an important role in health of the brain by reducing the risk of Alzheimer's disease.
To understand the differences, on the one hand there is the so-called “bad” LDL cholesterol (low-density lipoproteins), which can increase the risk of blockage of the arteries, heart attack and stroke when the recommended levels are exceeded.
On the other hand, “good” HDL cholesterol (high-density lipoproteins), which has a protective function by transporting cholesterol to the liver for elimination.
Researchers at the Keck School of Medicine at the University of Southern California recruited 180 healthy adults aged 60 and older, with an average age of 77 years and analyzed their blood plasma and cerebrospinal fluid. “People with higher levels of small HDL particles in the brain performed better on cognitive tests and had fewer amyloid plaques,” said Dr. Hussein Yassine, director of the study.
This effect occurred regardless of age, educational level, gender or whether participants were carriers of the APOE4 gene, which has previously been linked to an increased risk of Alzheimer's disease. The bond was even stronger in those without cognitive impairment, although the effect was less once people developed cognitive impairment, the scientist told Yassine to the Healthline health portal.
Another indicator associated with “good” cholesterol was the highest levels of a particular peptide, amyloid beta 42, in its cerebrospinal fluid. Although this small protein is actually a key warning sign for the onset of Alzheimer's disease when it folds incorrectly in the brain, having healthy beta amyloid does protect older adults from the disease.
The researchers concluded that the implication of their findings is that mechanisms that promote the formation of small HDL particles in the brain could play a role in preventing Alzheimer's disease.
“Now that we have a good goal to monitor and we will be able to find out which interventions (diet, exercise and medications) increase HDL, in the hope that this will translate into protecting our brains,” said Dr. Yassine.
“This study tells us to keep an eye on the history of fat metabolism in the brain,” said Dr. Paul E. Schulz, a neurologist at UTHealth Houston and Memorial Hermann-Texas Medical Center. The expert added: “As we discover more compounds that have a positive effect, we will be able to significantly reduce the risk of Alzheimer's disease.”
The researchers posed their new challenge: “If we could increase the activity of 'good fat carriers', such as HDL, and decrease the activity of the 'bad' could lead to better brain health and protection against Alzheimer's disease,” Schulz explained.
Describing Alzheimer's disease as “perhaps the worst disease ever”, the researcher was enthusiastic about the results: “This motivates all of us who study Alzheimer's disease to work hard on it to develop better treatments for this unpleasant disease.”
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