Either the estrogen patch or a placebo patch was given to 20 women for eight weeks for the study, which was published in the August 28 issue of Neurology, the scientific journal of the American Academy of Neurology.
"These results are hopeful, but they need to be confirmed with larger studies with more participants and longer treatment times," said study author Sanjay Asthana, MD, who conducted the study while at the VA Puget Sound Health Care System in Tacoma, Wash., and is now at the University of Wisconsin School of Medicine in Madison.
Previously, a small body of research suggested that estrogen may help relieve memory loss and other symptoms of Alzheimer's. But then several large studies showed estrogen has no effect on brain functioning in Alzheimer's patients.
Asthana noted differences between the current study and those that found no memory-enhancing effect. Asthana's study used estradiol, a type of estrogen that has been shown to have an effect on the brain. Other studies used a compound that contains low doses of estradiol along with other forms of estrogen that have not been proven to have an effect on the brain, he said. Also, the largest study finding no effect included only women who had hysterectomies. "We don't know enough yet about how a hysterectomy versus no hysterectomy can affect the brain's response to estrogen," he said.
In the current study, the women were given a variety of tests to measure their attention skills, recent verbal memory, recent visual memory and semantic memory, or the ability to name common items from pictures.
The women receiving estrogen improved their performance on an attention test by 20 percent more than the women receiving a placebo. Those receiving estrogen also improved on some of the tests of recent verbal and visual memory by 35 and 30 percent more than those receiving a placebo. On the test of semantic memory, those taking estrogen performed 10 percent better than those taking a placebo.
Researchers are still learning how estrogen works in the brain. Studies indicate that the hormone protects brain cells and may boost the level of acetylcholine, a chemical that carries messages between brain nerve cells and is lost in Alzheimer's patients.
Researchers are also continuing to investigate whether estrogen is effective in preventing Alzheimer's or delaying the onset of the disease, as some studies have suggested.
This study was supported by funds from Ciba-Geigy Corporation, now known as Novartis Pharmaceuticals Group, which is the maker of the estrogen skin patch, and the Department of Veterans Affairs.
The American Academy of Neurology recently released clinical practice guidelines regarding the detection, diagnosis and management of dementia. The practice guidelines can be found at www.aan.com.
The American Academy of Neurology, an association of more than 17,500 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. For more information about the American Academy of Neurology, visit its web site at www.aan.com.