“Good cholesterol” or high-density lipoprotein (HDL) is understood for its heart health advantages. But can an excessive amount of of it cause health issues? Researchers say extreme levels of HDL can raise the danger of dementia.

An excessive amount of or too little HDL can barely increase the danger of dementia, in accordance with a recent study, published within the medical journal Neurology. The study doesn’t show a causative link to dementia.

Cholesterol is a waxy, fat-like substance made by the liver essential for functions comparable to hormone synthesis and digestion. Cholesterol travels through two sorts of lipoproteins within the blood: LDL (low-density lipoprotein) and HDL.

High levels of LDL are related to the danger of heart disease because it builds up plaques and clogs the arteries, resulting in heart attacks and stroke. HDL, nonetheless, flushes out cholesterol through the liver and is subsequently considered to be heart-healthy.

The research team studied associations of HDL cholesterol and LDL cholesterol with dementia in a gaggle of 184,000 participants, who didn’t have dementia at first of the study. The common age of the participants was 70, and so they were followed up for 17 years. Their health behaviors were assessed using surveys, and levels of cholesterol were measured during routine health checkups.

In the course of the study, 25,214 people developed dementia. The common HDL level of the participants was 53.7 milligrams per deciliter. Healthy levels of HDL are 40 mg/dL for males and above 50 mg/dL for females. Participants were divided into five groups based on their HDL levels.

“Individuals with the best levels of HDL cholesterol had a 15% higher rate of dementia in comparison with those in the center group. Those with the bottom levels had a 7% higher rate of dementia in comparison with those in the center group,” the researchers said in a news release.

They took under consideration other aspects comparable to alcohol use, hypertension, heart problems and diabetes.

Researchers only found a slight association between LDL and dementia.

“Previous studies on this topic have been inconclusive and this study is particularly informative due to large variety of participants and long follow-up. This information allowed us to review the links with dementia across the range of levels of cholesterol and achieve precise estimates even for individuals with levels of cholesterol which are quite high or quite low,” study creator Maria Glymour, from Boston University, said within the news release.

The study has limitations because the survey was done on voluntary participants, which can not represent the larger population.

“The connection between HDL cholesterol and dementia is more complex than we previously thought. While the magnitude of this relationship is comparatively small, it is important,” said Erin Ferguson, a lead creator of the study from the University of California San Francisco.