A recent study sheds light on the correlation between cholesterol and Alzheimer’s disease in women.

Though it’s known as the “good cholesterol,” higher levels of HDL-C have been shown to correlate with heightened risk for Alzheimer’s disease.

A new study in the Journal of Clinical Endocrinology and Metabolism might explain why.

Once women reach the menopause transition, it’s a matter of the quality, rather than quantity, of the total cholesterol carried by HDL particles circulating in a woman’s bloodstream. And that quality declines over time, according to a research team led by Samar El Khoudary, professor of epidemiology in the School of Public Health at the University of Pittsburgh.

HDL particles vary in their size, composition, and level of functioning. The team measured these features in the blood of 503 women from the Study of Women’s Health Across the Nation (SWAN) HDL ancillary study.

The researchers found that, over time, the number of larger HDL particles in the women’s bodies increased—and these larger particles, unfortunately, did not function as well as their smaller counterparts.

The researchers conducted repeated assessments of study participants’ cognitive function from 2000 to 2016, comparing the data to changes in the women’s HDL particles, composition, and function as they aged.

“We were able to show that as early as midlife, women who have more of the smaller-sized particles and those whose particles’ concentrations of phospholipids increased over the menopause transition are more likely to experience better episodic memory later in life,” says El Khoudary, adding that loss of working memory is the first sign of Alzheimer’s disease.

Previously, her team has shown that health behaviors—including physical exercise, a balanced diet, and good sleep—work to improve the quality of HDL particles, for example by adding more of the phospholipid-rich particles in the bloodstream.

“That’s the good news in this developing picture of brain health and the ‘not-so-good-after-all’ cholesterol,” says El Khoudary.

“Even though higher levels of HDL-C may not be protective as you get older, there are things you can do that might help, even as early as your 40s.”

Additional coauthors are from the University of Pittsburgh; the University of Pennsylvania; Rush University; University of California, Los Angeles; Albert Einstein College of Medicine; University of Michigan; and University of Massachusetts.

Source: University of Pittsburgh

Original Study DOI: 10.1210/clinem/dgae697