In the first randomized, double-blind trial of the hormone for Alzheimer's disease, researchers gave 58 affected patients 100 mg hormone daily or an oral placebo. At baseline and 3 and 6 months, participants were tested for cognitive function and rated by physicians and caregivers regarding any changes in the severity of the disease.

Supplementation did not significantly improve cognitive performance or ratings of disease severity. A transient benefit on cognitive performance may have been seen on the tests conducted at 3 months, but the trend narrowly missed statistical significance, according to lead author Owen Wolkowitz, M.D.

Of the 58 people who started the study, 46 completed 3 months of treatment and 33 completed 6 months of treatment. According to David Knopman, M.D., who wrote an editorial accompanying the study, the small size of the study and the high number of people who dropped out may limit the findings. He suggested that larger studies are needed to test the findings.

The study was limited to people who were not taking medications that affect cognitive function, including drugs commonly used for Alzheimer's disease. Wolkowitz said this criterion may have contributed to the high drop-out rate because people chose to take an approved Alzheimer's drug instead of the supplement or placebo. He suggested that hormone supplementation should be tested in combination with these drugs to see whether it may enhance the results of the medications.

Wolkowitz added that no studies have been done on the long-term effects of such hormone supplementation. "Because it [dehydroepiandrosterone] metabolizes into testosterone and estrogen, it has the theoretical potential to stimulate the growth of hormone-sensitive cancers, such as breast or prostate cancers," he said. "The actual risk of this is an area of much debate among researchers."