For women, maintaining high levels of “good” HDL cholesterol may be one of the most effective strategies for fending off Alzheimer’s disease, according to new research.

Data from the ongoing Women’s Health Study indicate that women with the highest HDL levels - ranging from 60 to 75 - have half the risk of becoming mentally impaired as those with the lowest levels.

The findings were reported here at the International Conference on Alzheimer’s Disease and Related Disorders, organized by the Alzheimer’s Association.

Lead investigator Elizabeth Devore, a graduate student at the Channing Laboratory at Harvard Medical School in Boston, said women with the highest LDL (“bad”) cholesterol levels had a slight increase in risk of Alzheimer’s, but “clearly HDL is the more important in determining a woman’s risk.”

From 1992-95, the Women’s Health Study - an ongoing study of cardiovascular risk factors - collected baseline health and lifestyle data from 39,000 female health professionals, including blood samples from 75 percent of the cohort.

During the 1998-2000 evaluations, cognitive assessments were conducted on 4,081 subjects aged 65 or older. The odds of cognitive impairment declined with increasing levels of HDL.

Even “subtle decrements in cognitive function strongly predict eventual development of Alzheimer’s disease,” Devore and her colleagues point out in their report.

Their findings are “good news because we know how to modify HDL,” Devore said at a press conference. She noted that exercise, weight loss and moderate alcohol intake - one to two drinks a day - have all been shown to increase HDL levels. “But exercise is the most important element, even more important than diet.”

Asked if the findings could be generalized to men, Devore declined to speculate.