Fig. 1. Testosterone, the effect of α-reductase, is reduced to DHT, the strongest non-aromatizable androgen. DHT is then in Androstenediol from which metabolites 3α- and 3β-diol have a weak effect on AR while are more active on Erα and Erβ. 3α-diol activates GABA-receptors which regulate anxiety, depression and seizure. Testosterone is also aromatized in 17β-estradiol which, activating Erα and β, stimulates mitochondrial function, neurotransmission, and anti-inflammatory effect with consequent improved cognition. DHT and DHEAS activate the NMDA receptors which regulate memory, learning impairment, and psychosis. DHT: dihydrotestosterone, NMDA: N-methyl-d-aspartate, AR: androgen receptor.