DHEA is a steroid that occurs naturally in the blood of young people. Levels have been shown to peak between the ages of 20 and 30 years, but decrease progressively thereafter.
A synthetic form of DHEA is available as a supplement that is thought to possess anti-aging properties and help prevent Alzheimer's and other diseases.
The new study, conducted by Peter Schmidt of the Behavioral Endocrinology Branch of the National Institute of Mental Health in Rockville, Maryland set out to see whether there is any substance to DHEA's reported antidepressant-like effect. The findings are published in the February issue of the Archives of General Psychiatry (2005;62:122).
It involved 23 men and 23 women aged between 45 and 65 years and suffering from midlife on-set depression, who were randomly assigned to one of two groups.
The first group received six weeks of DHEA therapy - 90 mg per day for three weeks followed by 450 mg per day for three weeks. The second group received a placebo for six weeks.
None of the participants took any anti-depressant medication throughout the study period.
After the initial six weeks participants received no therapy for one or two weeks, after which the groups were reversed.
The participants depression levels were evaluated three and six months into each phase using the 17-Item Hamilton Depression Rating Scale, the Center for Epidemiologic Studies Depression Scale and the Derogatis Interview for Sexual Functioning.
The results showed a reduction of 50 percent or greater in the baseline of their depression rating score in 23 patients receiving DHEA therapy, compared to 13 patients receiving the placebo.
Although Schmidt and colleagues concluded that DHEA could be used to alleviate midlife-onset major and minor depression, they were cautious about its efficacy compared with other treatments.
"At present, there are no predictors of response, and with a 50 percent response rate one would obviously select more reliable first-line treatments for this condition."
However they added that for patients who do not respond to first-line treatment or who are unwilling to take traditional anti-depressant medication, DHEA may prove to be a useful alternative.
This is not the first time DHEA has been touted as an alternative to conventional medicine.
In 2004 researchers from the Department of Medicine at the Washington University School of Medicine published findings in JAMA (2004;292:2243-2248) that suggested DHEA could play a role in the prevention and treatment of the metabolic syndrome associated with abdominal obesity.
Italian researchers also suggested in the December issue of Fertility and Sterility (vol 80, issue 6, pp 1495-1501) that DHA could be used as an alternative to hormone replacement therapy for menopausal women.
However considerably more research into the effects of the hormone is required, as fears are raised from some quarters that its hormone production could stimulate the growth of hormone-sensitive cancers, such as breast or prostate cancers, and cause a build-up of cholesterol in the arteries.