[Actions of dehydroepiandrosterone: possible links with aging].
Dehydroepiandrosterone (DHEA) and its sulfo-conjugated derivative (SDHEA), secreted by the adrenal glands, are the most abundant circulating steroids in the human organism. The well-established fact that levels decrease progressively with age suggests a role in the aging process. They could also play a preventive role via an antitumoral action, stimulation of the immune system, an antiosteoporotic effect, a neuropsychologic action and cardiovascular protection. Nevertheless, it is not certain that evidence obtained from animal models can be transposed to man due to the specific nature of adrenal secretion of steroids in the human species. Epidemiological studies have often provided conflicting results. There have been few trials of administration in man, mostly aimed at studying the metabolic effects of DHEA. There is no evidence of secondary effects. Inversely, high-doses lead to transformation into active androgens with deleterious metabolic effects. Consequently, the current trend is to use low doses. Body weight, body composition, and sensitivity to insulin are not modified although variable effects on the lipid profile have been observed. Finally one study has produced much debate: a randomized trial demonstrating an improvement in wellbeing... Confirmation of this effect is certainly needed. In the absence of a satisfactory animal model, randomized prospective studies versus placebo are required to study the effect of substitution therapy in elderly subjects.