‘Good’ cholesterol RAISES dementia risk by 42 percent, study suggests

Despite the name, high levels of the “good” type of cholesterol, HDL, are associated with as much as a 42 percent increase in the risk of developing dementia.

High-density lipoprotein (HDL) is considered the good cholesterol compared to its 'bad' counterpart LDL because of its cardiovascular benefits.

Low-density lipoprotein (LDL) transports cholesterol particles throughout the body. It accumulates in the walls of arteries, causing them to become hard and narrow. This buildup is called plaque and can cause heart disease and stroke.

However, HDL absorbs cholesterol in the blood and returns it to the liver. The liver then flushes it out of the body. High levels of HDL have been shown to lower the risk of heart disease and stroke.

But now, one study published in the journal Lancet Regional Health – Western Pacific, found at very high levels, alters the structure and function of HDL and can even be harmful to the mind.

Currently, an estimated 5.8 million Americans suffer from Alzheimer's disease – the most common cause of dementia – with the vast majority over the age of 65

Researchers from Australia followed more than 18,600 people over the age of 65 over six years. Over the six years, 4.6 percent of participants were diagnosed with dementia.

Among people aged 75 and over, the risk of developing the disease was 42 percent. Overall, anyone with high HDL levels had a 27 percent increased risk of dementia.

The researchers found that the increased risk was independent of traditional risk factors for dementia, including physical activity levels, education, diabetes, smoking or alcohol consumption.

For adults, an HDL level of 40 mg/dL or higher is considered healthy for men and 50 mg/dL or higher for women.

The study assumed very high HDL levels of 80 mg/dl or higher.

In the study, the very high levels of HDL linked to dementia risk were unusual and not related to diet, but were more likely to indicate an underlying metabolic disorder.

While their findings were consistent with a 2022 study that found men and women with high HDL levels had an increased risk of dementia and Alzheimer's disease, researchers said the “explanation why high HDL-C could be associated with increased risk of dementia' is unclear.'

This may be partly due to the fact that HDL works very differently in the brain than in the rest of the body.

First author and senior researcher Dr. Monira Hussain from Monash University School of Public Health and Preventive Medicine said the findings could improve doctors' understanding of the mechanisms behind dementia, but stressed that more research is needed.

She said: 'While we know that 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 useful to consider very high HDL cholesterol levels in dementia risk prediction algorithms.'

Because cholesterol levels are easily measurable and certain lifestyle changes can affect them, measuring cholesterol may become a useful biomarker for dementia for some people.

Currently, an estimated 5.8 million Americans suffer from Alzheimer's disease – the most common cause of dementia – with the vast majority over the age of 65.

By 2050, this number is expected to rise to almost 13 million.

Although the main cause of Alzheimer's disease is still debated, scientists think the damage likely results from an abnormal buildup of proteins – amyloid and tau – in and around brain cells.

Dr. Corey Bradley, a cardiologist, told us Medical news today the terms “good” and “bad” cholesterol “simplify the differences between HDL and LDL.”

HDL is considered good because it helps transport cholesterol to the liver to be removed from the body, while LDL cholesterol builds up and leads to plaque.

Dr. However, Bradley added: 'What we are learning now is that there is much more nuance to the role of HDL in the body. As a result, I usually explain to patients that it is 'neutral' rather than 'good.'