Evaluation of the circadian profiles of serum dehydroepiandrosterone (DHEA) cortisol, and cortisol/DHEA molar ratio after a single oral administration of DHEA in elderly subjects

Aging is associated with a selective decline in circulating levels of dehyd roepiandrosterone (DHEA) and its sulfate, with no major changes in cortisol secretion. In young subjects, serum levels of both DHEA and cortisol are r egulated according to a circadian rhythm, and an age-related attenuation of DHEA. but not cortisol, circadian rhythmicity has been reported. Several t rials have evaluated the effects of DHEA supplementation in elderly subject s, although the results are still controversial. However, no data are avail able on the 24-hour profile of DHEA circulating levels in elderly subjects with DHEA administration. In the present study, we evaluated the circadian rhythms of DHEA, cortisol, and the cortisol/DHEA molar ratio in old subject s treated with either placebo (old-PL) or a single 50-mg dose of DHEA (old- D), both administered orally at 0700 hours. For each variable, the circadia n profiles were compared with those obtained in young control subjects. The group of young subjects displayed a circadian rhythm for both DHEA and cor tisol serum concentrations but no rhythm for the cortisol/DHEA molar ratio. In the old-FL group, the circadian rhythm of DHEA was completely abolished , whereas significant rhythms for both cortisol and the cortisol/DHEA molar ratio were observed. Particularly, at each time point, the cortisol/DHEA m olar ratio was significantly higher in these subjects versus the young grou p. In the old-D group, the circadian rhythm of DHEA was completely restored and was comparable to that observed in the young group. Analogous to the o bservations in young subjects, the profile of the cortisol/DHEA molar ratio in old-D subjects did not display any circadian rhythmicity, the values be ing almost. completely comparable to those observed in young controls. Our data demonstrate that the circadian rhythm of DHEA is totally abolished in elderly subjects. A single 50-mg dose of DHEA administered orally at 0700 h ours restores the circadian rhythmicity of serum DHEA and almost completely normalizes the 24-hour profile of the cortisol/DHEA molar ratio in old sub jects without: affecting the cortisol circadian rhythm. Copyright (C) 2000 by W.B. Saunders Company.