How it works
DHEA is synthesised from cholesterol through the sequential action of CYP11A1 and CYP17A1 enzymes in the zona reticularis, the innermost zone of the adrenal cortex; roughly 90% of circulating DHEA originates from this source, with minor contributions from the gonads and brain 4. Rather than circulating freely, most DHEA is rapidly sulphated to form DHEAS, its stable reservoir form with a half-life of approximately 10-11 hours versus roughly 30 minutes for free DHEA 43.
In peripheral tissues, DHEAS is desulphated and converted locally into active androgens (testosterone, DHT) or oestrogens according to cellular need. This local, cell-specific hormone manufacturing is called intracrinology, and it explains why blood levels of DHEA or DHEAS do not reliably predict how much active sex hormone any given tissue is actually producing 3. The adrenals account for nearly all DHEA output; the ovaries and testes contribute only marginally.
Beyond its precursor function, DHEA acts directly as a neurosteroid, crossing the blood-brain barrier to modulate GABA-A, NMDA, and sigma-1 receptors, thereby influencing neuronal growth, myelination, and synaptogenesis 4. DHEAS concentrations peak in the late twenties and subsequently decline approximately 2-5% per year, driven by reduced 17,20-lyase activity and shrinkage of the zona reticularis; by the seventh decade, levels typically sit at 20-30% of youthful values 31. This lifelong trajectory is termed adrenopause.
Example
An athlete in the final weeks of a competition preparation phase is sleeping six hours, training twice daily, and restricting calories. Serum cortisol climbs; DHEA output does not scale proportionally. The cortisol-to-DHEA ratio widens. Recovery markers deteriorate, libido falls, and mood becomes brittle. The body's hormonal balance has shifted toward a state of net physiological stress with insufficient anabolic counter-pressure.
The symptoms point not to overtraining in isolation, but to a specific neuroendocrine imbalance that training adjustments alone cannot resolve.
Why it matters
DHEA functions as a physiological counter-weight to cortisol. In acute stress, both hormones rise, but a 2021 meta-analysis of 14 studies confirmed DHEA as a reliable biomarker of acute stress response, with the magnitude modulated by sex, age, and adiposity 2. When the cortisol-to-DHEA ratio becomes chronically elevated, the consequences extend beyond the endocrine system: the evidence links a widened ratio to cognitive deterioration, impaired hippocampal function, and accelerated biological ageing 24.
The supplementation picture is more nuanced. The landmark DHEAge trial (n=280, ages 60-79) found that 50 mg/day for one year restored serum DHEAS to youthful concentrations and improved bone turnover in older women, skin hydration, and libido, without adverse biochemical consequences 1. Yet clinical guidelines do not endorse DHEA for general anti-ageing or performance use: evidence remains inconsistent, and long-term supplementation carries potential risks including oestrogenic effects and reductions in HDL cholesterol 3. The gap between population-level DHEA decline and individual benefit from supplementation remains open.
What does DHEA do in the body?+
DHEA serves two distinct functions: it acts as a circulating precursor hormone, converted in peripheral tissues into androgens and oestrogens according to local cellular demand; and it acts directly as a neurosteroid, modulating GABA-A, NMDA, and sigma-1 receptors to support neuronal growth and synaptogenesis. Both functions decline with age.
Why do DHEA levels decline with age?+
The decline, termed adrenopause, results from two age-related changes: a reduction in 17,20-lyase enzyme activity and a decrease in the mass of the zona reticularis, the adrenal zone where DHEA is manufactured. DHEAS concentrations typically fall to 20-30% of peak values by the seventh decade, a trajectory that begins in the early thirties.
Does DHEA supplementation work?+
The evidence is mixed and population-dependent. The DHEAge trial demonstrated that 50 mg/day for one year restored DHEAS to youthful levels in adults aged 60-79 and improved bone turnover, skin quality, and libido in older women without adverse biochemical effects. However, clinical guidelines do not endorse DHEA for general anti-ageing or performance use, citing inconsistent evidence and potential risks.
What is the cortisol-to-DHEA ratio and why does it matter?+
The cortisol-to-DHEA ratio measures the relative balance between the body's primary stress hormone and its principal adrenal counter-regulatory hormone. A chronically elevated ratio, where cortisol dominates, is associated with cognitive deterioration, impaired hippocampal function, and accelerated biological ageing. A 2021 meta-analysis confirmed DHEA as a reliable acute-stress biomarker, with ratio responses varying by sex, age, and body composition.
