Antidepressant and cognition-enhancing effects of DHEA in major depression

Modulation of GABA-gated chloride ion influx in the brain by dehydroepiandrosterone and its metabolites

Both DHEA and GABAA receptor agonists are known to reduce anxiety. Since GABAA receptor agonists are generally thought to elicit their anxiolytic effects by facilitating neuronal uptake of chloride ion, we set out to evaluate whether DHEA elicits its anxiolytic effects by a similar mechanism. The results of the studies show an uneven distribution of basal and GABA-stimulated chloride uptake in different regions (cerebellum, pons-medulla, striatum, hippocampus, mid-brain, hypothalamus and cortex) of rat brain. Contrary to our expectations, however, both DHEA and DHEAS inhibited GABA-mediated chloride uptake with DHEAS being more potent than DHEA. On the other hand, delta 4-androstenedione, another DHEA metabolite, did not have any effect on chloride uptake in any region of the brain. In conclusion, the data presented here, therefore, suggest that DHEA and DHEAS may elicit anxiolysis through mechanisms independent of GABAA receptor-mediated facilitation of neuronal chloride uptake.

Glucocorticoid medication, memory and steroid psychosis in medical illness

Steroid psychosis, including associated cognitive changes, is infrequent with short-term low-dose GC treatment, especially if only major objectively discernible effects are assessed. With long-term or high-dose treatment, however, or if milder subjectively discernible symptoms are also assessed, the incidence may be quite high. In lupus cerebritis, the differentiation between cognitive difficulties secondary to the underlying illness, which might warrant more aggressive GC treatment, versus those secondary to GC treatment itself, which might warrant dosage reduction, may be problematic, but certain guidelines have been proposed. Although GCs are widely prescribed and represent a clinically important class of medication, their deleterious effects may also be considerable. Glucocorticoids have prominent effects on central nervous system biochemistry and electrophysiology, and recent reports suggest they make certain hippocampal neurons more vulnerable to a variety of metabolic insults. Indeed, the clinical literature reviewed here is consistent with a disruption of hippocampus-dependent memory function (perhaps in conjunction with other areas of dysfunction), although in most cases the disruption is relatively mild and, in the vast majority, if not all cases, is reversible. From a clinical prospective, it is important to discuss potential neuropsychiatric side effects with patients before prescribing GC treatment. A greater understanding of the risk factors for experiencing SP and of its underlying mechanisms will lead to more informed clinical decision making and to a greater understanding of the role exogenous, and perhaps endogenous, GCs play in human cognition and behavior.