New study claims 'good' cholesterol may actually raise the risk of dementia

06 January 2024 , 17:47

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Men and women with high levels of HDL had an increased risk of dementia and Alzheimer's disease (Image: Getty Images/Science Photo Library RF)

A new study shows that while ‘good’ cholesterol lowers the risk of heart disease, it may actually increase the risk of developing dementia.

HDL cholesterol, or High-density lipoprotein is known as ‘good’ cholesterol because it absorbs cholesterol in the blood and carries it back to the liver which flushes it out of the body. This is opposed to ‘bad’ LDL or low-density lipoprotein cholesterol, which builds up in the arteries increasing the risk of heart disease or stroke.

High levels of HDL ‘good’ cholesterol has been shown to lower the risk of heart disease and stroke but now a study published in the journal Lancet Regional Health - Western Pacific, shows that it might contribute to developing dementia. Researchers looked at more than 18,000 people aged over 65 over a period of six years - in that time 4.6 percent of them got dementia.

Among people who were 75 years and older, the risk of developing the disease was 42 percent. Overall, anyone with high HDL levels had a 27 percent increased risk of dementia. The Australian study corrected other risk factors like physical activity levels, education, diabetes, smoking or alcohol consumption. The scientists said the increased risk was independent from all these traditional dementia risk factors.

For the study, very high levels of HDL were considered to be 80 mg/dL or higher - a healthy adult woman should have 50 mg/dL or higher and it is 40 mg/dL or higher for men. However the study identified those with very high HDL levels were uncommon and it was more likely to be linked to an underlying metabolic disorder than be diet related.

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At present there are 900,000 people living with dementia in the UK (Getty Images)

HDL levels can also be impacted by lifestyle changes, similar to how people try and curb ‘bad’ cholesterol now, so if it does turn out to be a contributing factor to developing Alzheimer's, it might also prove an effective way to influence the disease in patients in future.

Dr Monira Hussain, who worked on the study, said: '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. It may be beneficial to consider very high HDL cholesterol levels in prediction algorithms for dementia risk.”

Dr. Corey Bradley, a cardiologist, told MedicalNews Today “What we are learning now is that there is a lot more nuance to HDL’s role in the body. As a result, I usually explain to patients that it is more "neutral" than "good."'

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