Science Alert casts some doubt on the “good” part of “good” cholesterol, with research that links high levels of HDL cholesterol with a higher likelihood of developing dementia:
For those above 75 years of age, the risk increases by 42 percent, the analysis showed.
The research, led by a team from Monash University, looked at data on 18,668 adults aged over 65 from Australia and the US. Overall, for those diagnosed as having high HDL-C levels the risk of dementia increased by 27 percent on average, with individuals followed for an average of 6.3 years.
“This is the most comprehensive study to report high HDL-C and the risk of dementia in older people,” write the researchers in their published paper. “Findings showed that high HDL-C was associated with dementia risk and the risk increased with age.”
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A normal level of HDL-C in the blood is considered to be 40–50 milligrams per deciliter (or mg/dL) for men, and 50–60 mg/dL for women – roughly 40–60 parts per thousand. Almost 15 percent of the participants (2,709 people) had what was regarded as high HDL-C levels as the study started, which is 80 mg/dL or above.
The increase in risk is quite a jump, and the association remained significant when adjusted for factors such as age, sex, education, alcohol consumption, and daily exercise. However, this doesn’t prove the cholesterol is causing the increase in dementia – only that there’s evidence of a link.
“While we know HDL cholesterol is important for cardiovascular health, this study suggests that we need further research to understand the role of very high HDL cholesterol in the context of brain health,” says epidemiologist Monira Hussain from Monash University.