By Kathleen Doheny
WEDNESDAY, Nov. 4, 2015 (HealthDay News) -- The drug raloxifene doesn't help the declining memory and thinking skills of women who have mild to moderate dementia due to Alzheimer's disease, a small study suggests.
"We found no effect," said study researcher Dr. Victor Henderson, professor of health research and policy and neurology and neurological sciences at Stanford University in California.
Raloxifene is a complex drug. It acts like the female hormone estrogen in some parts of the body, while it blocks the effects of estrogen in the breasts and uterus, the study authors explained.
The researchers decided to look at the drug after another study of raloxifene, which is also used to treat the bone-thinning disease osteoporosis, found that the drug reduced the risk of healthy women developing impairments in their thinking and memory, Henderson said.
The new study, published online Nov. 4 in Neurology, included 42 women who were recruited between 2006 and 2009 from several sites across the United States. The study participants, aged 68 to 84, all had late-onset Alzheimer's disease that was in the mild to moderate stages.
The women were randomly assigned to take raloxifene or an inactive placebo pill for a year. The researchers tested the women's memory and other mental functions at the start of the study and every three months after that.
Test scores didn't differ significantly between the two groups, the investigators found. The scores didn't differ for memory and thinking skills, or how well the women could perform activities of daily living such as dressing themselves and other routines.
However, because the number of women in the study was so small, with only 21 women receiving treatment with raloxifene, "this study can't exclude a small effect," Henderson said.
In addition, the findings don't rule out that other drugs similar to raloxifene might have a benefit on thinking and memory, Henderson said. Raloxifene belongs to a class of drugs known as SERMs (selective estrogen receptor modulators). "The SERMs don't all act in the same way," he said.
"What this study shows," said Heather Snyder, senior director of medical and scientific operations for the Alzheimer's Association, "is that in this population, they don't see a big benefit" with raloxifene.
However, she added, scientists are still trying to understand the genetic and biological reasons for Alzheimer's, including hormonal pathways.
"I think there are a lot of things we don't understand about the underlying biology and the role of these different pathways for Alzheimer's disease," she said.
About 5 million Americans are living with Alzheimer's disease, according to the Alzheimer's Association, although not all are diagnosed. Of those, two-thirds are women, Snyder said, "but we don't know why."
Women's generally longer life expectancy may be one factor, but there may also be biological and genetic reasons, Snyder said.
Some of Henderson's co-researchers report serving as consultants or speakers for Eli Lilly, which provided the study drug, and other pharmaceutical companies. The U.S. National Institutes of Health supported the study.