DHEA is readily available over the counter in the United States and in other countries and has been widely touted and used by the general public as a preventive agent against many of the chronic diseases associated with aging. Unlike the participants in the majority of published studies, participants in the current study were not selected for lower levels of DHEA, enabling an examination of the effects of DHEA supplementation on cognitive function and quality of life in the general population. The results of this clinical trial provide no evidence for a beneficial effect of supplementation with 50 mg daily of DHEA on cognitive function in healthy older adults. Likewise, there were no beneficial effects of DHEA supplementation on quality of life, including mood, perceptions of physical and emotional health, life satisfaction, or sexual function.
The results of this year-long clinical trial are in accord with other shorter-term studies with smaller sample sizes that also found no effects of DHEA supplementation on cognitive function.9,15–18
For instance, no effects of DHEA were found on cognitive function in a nonclinical sample of 46 men aged 62 to 76 who received 50mg DHEA daily for 13 weeks followed by placebo or the reverse.9
Similarly, a clinical trial of 60 symptomatic perimenopausal women aged 45 to 55 randomized to 50 mg/day of DHEA or placebo for 3 months found no differences in cognitive function, although DHEA supplementation did affect endocrine profiles.16
Furthermore, no effect of DHEA supplementation on cognitive function was observed in a clinical trial of 24 women with primary and secondary adrenal insufficiency.18
Although one study13
reported a beneficial effect of 2 weeks of DHEA supplementation (50 mg/day) on one of six cognitive function tests (picture memory) in women but not men, it is unclear whether this effect would have persisted over a longer period, whether it was a practice effect or due to multiple comparisons. It is reassuring that, unlike a few previous studies,14,19
there were no detrimental effects of DHEA on cognitive function observed in this study.
Men and women in this study showed significant improvement in mood, and women showed improvement on one measure of life satisfaction over time regardless of whether they received DHEA or placebo, but these improvements were small and, although statistically significant, are unlikely to be of clinical significance. Furthermore, improvements for men and women taking DHEA were no different from those observed for men and women taking placebo, and there were no differences observed between the DHEA and placebo groups on sexual function or the SF-36 measures. Thus, the results of this study do not support a beneficial effect of DHEA supplementation on quality of life.
The lack of an effect of DHEA on quality of life observed in this study, although in accord with some shorter-term studies,9,16,17
conflicts with others showing beneficial effects.13,18
In one study, women (but not men) showed a nonsignificant trend toward better mood and fewer psychological and physical complaints after 2 weeks of DHEA supplementation,13
but the study sample consisted of only 15 women. It is unclear whether a longer duration of supplementation or use of a larger sample size would have yielded similar results. In a 4-month, double-blind, randomized, placebo-controlled trial with a crossover design, DHEA significantly improved overall well-being and depression and significantly increased sexual interest and satisfaction with sex in 24 women with adrenal insufficiency.18
Results of the present study suggest that a similar benefit cannot be expected in women (or men) with normal adrenal function.
Several limitations of this study were also considered. By design, this trial assessed the benefits of DHEA supplementation in a healthy sample of men and women. With an average Modified Mini-Mental State Examination score of 96, the participants in this study were limited to those who were not cognitively impaired. Effects of DHEA supplementation may be different for those not cognitively intact or scoring poorly on cognitive function tests at a baseline evaluation. Likewise, levels of depressed mood were low, and life satisfaction scores were fairly high in this cohort. It is unknown whether long-term DHEA supplementation would have an effect in clinically depressed individuals or those with a low quality of life. It is unlikely that the lack of observed effects for DHEA was due to differential adherence; adherence was high in both groups, and changes in DHEA levels in the treatment and placebo groups were consistent with adherence to use. It is also unlikely that the lack of observed effects was due to a lack of statistical power, which was greater than 0.80 for all outcomes.
In conclusion, this study of healthy older men and women who were not selected for endogenous DHEA levels failed to show any benefits from DHEA supplementation for 1 year on cognitive function, mood, quality of life, or sexual function. These results were observed despite restoration of youthful DHEA levels in men and women and enhancement of estrogens and testosterone in women. Although it is unknown whether DHEA supplementation may benefit specific subgroups of men and women, such as those who are clinically depressed or cognitively impaired, the present results suggest that DHEA supplementation should not be recommended for enhancement of cognition or wellbeing in the general population.