Study Finds Surprising Link: High ‘Good’ Cholesterol Levels May Increase Dementia Risk

Over 17 years, analyzing medical records for over 184,000 individuals revealed an average age of 70.

A recent study suggests that even elevated levels of ‘good’ cholesterol, or high-density lipoprotein (HDL) cholesterol, can increase the risk of dementia.

 

Cholesterol is classified into HDL cholesterol and low-density lipoprotein (LDL) cholesterol.

As a type of fat, cholesterol can’t circulate in the bloodstream. It is carried by lipoproteins and is classified as HDL cholesterol or LDL cholesterol, depending on the size of the lipoprotein particles.

LDL, known as ‘bad’ cholesterol, carries cholesterol to the walls of blood vessels, causing it to accumulate. In contrast, HDL, called ‘good’ cholesterol, removes the cholesterol accumulated on the walls of blood vessels for processing in the liver.

A research team led by Maria Glymour, a professor of epidemiology at Boston University School of Medicine, analyzed 17 years of medical records of over 184,000 participants (average age 70) in the Kaiser Permanente ‘Northern California Health Plan.’ According to HealthDay News on the 9th, the findings revealed the facts above.

The average HDL cholesterol level in the blood is 40mg/dL or higher for men and 50mg/dL or higher for women.

The average HDL cholesterol level of the study participants was 53.7mg/dL.

The research team classified the participants into five groups based on their HDL cholesterol levels, with those with 65mg/dL or higher in the top group.

The average follow-up period was 9 years, during which over 25,000 people were diagnosed with dementia.

The analysis showed that the group with the highest HDL cholesterol levels had a 15% higher incidence of dementia than the middle group.

Also, the group with the lowest HDL cholesterol levels (11-41mg/dL) had a 7% higher incidence of dementia than the middle group.

Even after considering other variables such as drinking, high blood pressure, cardiovascular disease, and diabetes, these results remained unchanged, the research team said.

On the other hand, LDL cholesterol levels were not associated with the risk of dementia.

This suggests that HDL cholesterol has a complex relationship with dementia, just as it does with heart disease and cancer, the research team explained.

Some studies show that if HDL cholesterol levels are excessively high, the risk of cardiovascular disease and death from all causes increases.

The degree of dementia risk revealed in the analysis is not very high, and the clinical significance of this is unknown, the research team said.

In response, Dr. Howard Weintraub, clinical director of the Cardiovascular Prevention Center at New York University, commented that while very high levels of HDL cholesterol, such as 90mg/dL or 100mg/dL, are unknown, a level of around 65mg/dL is not associated with dementia.

The American Academy of Neurology (AAN) cautiously stated that high or low HDL cholesterol levels do not prove to be the cause of dementia.

The results of this study were published in the latest issue of the journal ‘Neurology’ of the American Academy of Neurology.