Libido is the drive to have a sexual activity. Gonadal hormones play a major role in activating and maintaining libido in both men and women. Other hormones, though, interact with them in influencing sexuality, such as prolactin and also brain neurotransmitters. The role of hormones declines with age and sexuality becomes more mind-induced. Nevertheless, some aspects of sexuality remain linked to hormones. For example, a reduction of central arousability is typical of hypogonadal state. However, it is not clear at what level of androgen deficiency the loss of libido begins and if adequate external stimuli can overcome a partial deficiency.