"Good" cholesterol has been linked to dementia
A large amount of "good" cholesterol increases the risk of dementia in the elderly. This is the conclusion reached by a group of Australian scientists. It is supposed to help doctors recognize a group of patients potentially at risk of dementia.
Cholesterol is a substance that is found in every cell in the body and keeps it healthy. It is carried through the body by low-density lipoproteins (LDL) - this cholesterol is considered "bad" because it clogs blood vessels. Cholesterol that is carried by high-density lipoproteins is called "good" because its excesses are themselves eliminated from the body.
In past studies, scientists have reported a link between high levels of high-density lipoprotein (HDL) cholesterol in the blood and the risk of all-cause mortality, age-related degeneration of the yellow spot of the eye, sepsis, and fractures. The association with dementia risk remained unclear. Experts from Monash University (Australia) decided to answer this question.
They conducted one of the largest studies of elevated levels of HDL cholesterol and dementia in initially healthy elderly people aged mostly over 70 years. The results are published in The Lancet Regional Health - Western Pacific.
The data were taken from the ASPREE research paper, a double-blind, randomized, placebo-controlled trial of daily low-dose aspirin use in healthy older adults. From 2010 to 2014, ASPREE recruited 16,703 participants over 70 years of age from Australia and 2,411 people over 65 years of age from the United States with no evidence of dementia. Dementia for all causes was considered the primary endpoint of the study and was defined by Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-IV) criteria.
Very high levels of HDL cholesterol were classified as 80 milligrams per deciliter or higher. Optimal HDL levels for heart health are generally between 40 and 60 milligrams per deciliter for men and 50 to 60 for women.
Researchers recorded 850 (4.6%) cases of dementia among 18,668 participants over 6.3 years. People over 75 with high HDL levels (more than 80 milligrams per deciliter) had a 27% increased risk.
According to the scientists, such high levels of HDL are not related to dietary factors, but may indicate a metabolic disorder.
The authors hope their findings will improve understanding of the mechanisms underlying dementia, but more research is needed.
"While we know that HDL cholesterol is important for cardiovascular health, there is a need to understand the role of very high levels of HDL cholesterol in the context of brain health," the researchers concluded.