The supplement dehydroepiandrosterone (DHEA), touted by some as an anti-aging hormone and a treatment for diseases such as cancer, diabetes and Alzheimer's disease, showed no effect on patients with Alzheimer's disease, according to a study published in this week's Neurology.
DHEA is a hormone produced naturally in the adrenal glands. The body then converts it into the hormones oestrogen and testosterone. DHEA as a supplement is made from plant chemicals.
In the first randomized, double-blind trial of DHEA for Alzheimer's disease, researchers gave 58 Alzheimer's patients either 100mg of DHEA or a placebo daily. Before the study began and at three and six months, the patients were tested for cognitive functioning and rated by doctors and carers on any changes in the severity of the disease.
DHEA did not significantly improve cognitive performance or disease severity, reported the researchers. A transient benefit on cognitive performance may have been seen on the tests at three months, but the benefit narrowly missed statistical significance, according to study author Dr Owen Wolkowitz from the University of California at San Francisco.
Of the 58 people who started the study, 46 completed three months of treatment and 33 completed six months of treatment.
In an accompanying editorial, neurologist Dr David Knopman, of the Mayo Clinic in Rochester, Minnesota, said that the small size of the study and the high number of people who dropped out may limit the findings. He said that larger studies are needed to test these results.
The study was limited to people who were not taking medications that affect cognitive functioning, including drugs commonly used for Alzheimer's. Wolkowitz said this criterion may have contributed to the high drop-out rate, with people choosing to take the Alzheimer's drug instead of DHEA or placebo. Wolkowitz said DHEA should be tested in combination with these drugs to see whether DHEA may enhance the results of the drugs.
Side effects occurring more often in the patients taking DHEA included confusion, agitation and anxiety. Wolkowitz said no studies have been done on the long-term effects of taking DHEA supplements.
"Because it metabolises into testosterone and oestrogen, it has the theoretical potential to stimulate the growth of hormone-sensitive cancers, such as breast or prostate cancers. The actual risk of this is an area of much debate among researchers," said Wolkowitz.
Interest in DHEA stems from the findings that the level of DHEA in the body peaks between ages 20 and 30 and then decreases progressively with age, as well as other studies showing that DHEA improves memory in mice. However studies on the levels of DHEA in the blood of Alzheimer's patients have been conflicting.
The study was funded by a grant from the National Institute on Aging and by Neuroscience Pharma, based in Montreal, which also supplied the matched active and placebo capsules.