The Women's Health Initiative Memory Study (WHIMS), a part of the WHI project, found that combined hormone therapy (estrogen plus progestin under the brand name Prempro) doubled the risk for probable dementia in women 65 and older and did not prevent mild cognitive impairment. Of the 4,532 women enrolled in the memory study and monitored for approximately five years, 61 (1.3 percent) were diagnosed with probable dementia – of those, twice as many (40) were taking estrogen plus progestin compared to those (21) in the placebo group.
"The findings translate into 23 additional cases of dementia for every 10,000 women annually, which means the risk to an individual remains low," said Rebecca Jackson, an endocrinologist and the Women's Health Initiative principal investigator at The Ohio State University Medical Center, who co-authored the memory study.
"But the concern over increased risk coupled with the fact that hormone replacement therapy offers no cognitive benefits led us to recommend that women should not take the combination of estrogen and progestin in an effort to prevent age-associated memory loss.
And, with this additional evidence, it appears this therapy could be more harmful than helpful to postmenopausal women."
Women in the estrogen plus progestin part of the WHI trial stopped taking their study pills in July after research results indicated that for those on the combined therapy, the overall risks (breast cancer, heart attacks, stroke and blood clots) outweighed the benefits (fewer fractures and colorectal cancers).
Memory study participants' cognitive function was tested at the start of the study and then annually with a standard mental state examination. Cognitive measures also were determined by friends or family members who could provide information about the participants' cognitive and behavioral function.
WHIMS researchers' intent was to determine whether estrogen – either alone or combined with progestin – could reduce the risk of dementia and mild cognitive impairment in healthy women who are 65 and older.
Dementia involves progressive impairment of all aspects of brain function and is characterized by changes in memory, personality and behavior, and difficulty in carrying out normal daily activities. Mild cognitive impairment refers to a specific type of memory loss, in which people have sharp thinking and reasoning skills, but a decline in their short-term memory.
Though the combined hormone replacement therapy segment of the WHI was halted during the summer for the safety of the participants, the Women's Health Initiative's estrogen-only trials are continuing.
The WHIMS is funded in part by Wyeth Pharmaceuticals, manufacturer of Prempro. The WHI is funded by the National Heart, Lung, and Blood Institute. Jackson has received research support from Merck and Pfizer.
Contact: Emily Caldwell, Medical Center Communications, 614-293-3737 or caldwell.151@osu.edu
Journal
JAMA