(Chicago-AP) -- Estrogen pills appear to slightly increase the risk of Alzheimer's disease and other types of dementia in postmenopausal women.
That's the finding of a government study called the Women's Health Initiative.
The findings contradict a long-held belief that estrogen pills can help keep the minds of older women sharp.
Doctor Tamsen Bassford of the University of Arizona says the important take-home message is the lack of protection for women taking hormones _ even estrogen alone.
Bassford has led the Arizona arm of the study.
The research involved nearly three-thousand women between the ages of 65 and 79 who had hysterectomies and had taken estrogen-only pills for an average of five years.
The researchers found estrogen users faced a 38 percent increased risk of developing dementia or forgetfulness.
The study appears in the latest Journal of the American Medical Association.