Having High Levels of ‘Good’ Cholesterol May Increase Risk of Dementia, Study Finds
New research suggests that having high levels of so-called “good” cholesterol may actually raise the risk of developing dementia. Scientists conducted a study tracking rates of dementia among 185,000 individuals over the course of nearly a decade. The study found that participants with the highest levels of high-density lipoprotein (HDL) cholesterol, which is considered the good kind, were 15% more likely to develop dementia compared to those with average readings. Meanwhile, individuals with the lowest levels of HDL cholesterol faced a 7% increased risk.
HDL cholesterol is commonly known as the “good” kind of cholesterol because it removes cholesterol from arteries and carries it to the liver to be broken down and removed from the body. This process reduces the risk of heart attacks and strokes. However, recent research has challenged the notion that higher levels of HDL cholesterol are always beneficial. Some studies have suggested that excessive levels of HDL cholesterol can contribute to inflammation or even clog arteries, leading to reduced blood flow to the brain and an increased risk of dementia.
The Boston University study, although observational and unable to establish causation, found no link between levels of low-density lipoprotein (LDL) cholesterol, commonly known as the “bad” kind, and dementia.
Cholesterol is a fatty, waxy substance found in the blood that is essential for bodily functions such as digestion, hormone production, and vitamin D synthesis. However, excessive cholesterol can accumulate in the blood due to factors such as poor diet, lack of exercise, obesity, smoking, and excessive alcohol consumption. High cholesterol levels can lead to blocked blood vessels and increase the risk of heart problems and strokes. Detecting high cholesterol requires a blood test, but it does not typically exhibit any symptoms. It is worth noting that “good” cholesterol, or HDL cholesterol, has been shown to protect against heart disease.
The results of this study surprised the researchers, who noted the complex relationship between HDL cholesterol and dementia. The study followed 184,367 participants over an average of nine years, with regular cholesterol measurements and health record tracking. Out of the participants, 25,214 developed dementia during the study. The average HDL cholesterol levels among participants were 53.7 milligrams per deciliter (mg/dL), with levels above 40mg/dL for men and 50mg/dL for women considered healthy. Participants with the highest levels had levels above 65mg/dL, while the lowest levels were grouped as 11 to 41mg/dL. The study took into account other factors that could influence dementia risk, such as alcohol consumption, blood pressure, cardiovascular disease, and diabetes.
Professor Maria Glymour, the study’s lead author, stated that the elevation in dementia risk associated with both high and low levels of HDL cholesterol was unexpected. However, she emphasized that the increases in risk were small and their clinical significance remains uncertain. She also noted that no association was found between LDL cholesterol and dementia risk in the overall study cohort. The researchers acknowledged that the study participants were volunteers, potentially limiting the generalizability of the findings.
Previous studies have also suggested a link between high cholesterol in middle age and an increased risk of developing dementia. The complex relationship between cholesterol and various health conditions continues to be an area of ongoing research, with researchers urging further investigation to better understand these associations.