Study: Hormone Replacement Therapy Might Shrink Brains

Jan. 13, 2009— -- A new study is showing negative effects of a once-popular therapy for postmenopausal women, leading some to wonder how it might affect younger women still using the treatment.

The National Institutes of Health study looked at women from the Women's Health Initiative Memory Study, which is a subset of the largest study of hormone replacement therapy. The study found that, overall, women taking the hormones had smaller frontal brain lobes than women who did not follow the treatment.

"Older women who took these [hormones] ... they had greater brain atrophy in these brain regions that are critical for the maintenance of memories," said Susan Resnick, a senior investigator at the National Institute on Aging, Laboratory of Personality and Cognition, and the study's primary author.

Hormone replacement therapy, a regimen of progestin and estrogen given to relieve symptoms of menopause, initially fell from favor in 2002 when the Women's Health Initiative Memory Study was stopped because of concerns that the treatment was putting the women involved at greater risk for stroke and heart problems.

The International Menopause Society in May released new guidelines saying the original guidelines were flawed and advised that the therapy may be safe for women younger than 65.

In this new study, women older than 65 were shown to have an decrease in brain volume if they took the hormone therapy. In the past, such reduction in brain size had been associated with a decline in memory, and Resnick expects those results to replicate when they analyze cognition test scores.

"We actually found negative effects, both on memory and the risk for dementia," she said of studies done in the past in this area.

She noted, however, that the hormone regimen seemed only to accelerate a mental decline in women who had shown signs of decline before starting treatment.

"If we take women with healthy looking brains, we didn't see a negative effect," Resnick said.

She noted that when women first began hormone treatments, it was expected to boost rather than impair brain power. But studies have since shown otherwise.

Women now on hormone therapy probably have little to fear at this time from the study, as recommendations would exclude any women of the ages looked at in the study from taking hormone therapy.