The diminution of desire is a frequent reason for a visit to the Andrologist, not only after 50 years of age, but also for younger subjects. Sexual desire or libido, at the same level of dream, hunger, thirst, is a pulsation that we define as "sexual appetite". It is present in the individual from puberty to the rest of his or her life with a normal variation linked to age; in the healthy subject, this desire is conserved even at an advanced age.

Like other impulses, the libido is connected with other specific areas of the brain, localised principally in the limbic system, which is considered as the centre of desire. It is so central that it is then largely connected to other areas, such as the centres of pleasure, pain, smell, etc. Furthermore, there are ample links with the memory circuit, relegated for collection, to the processing of the information relevant to experience.

In both a positive and negative sense, it has a certain rapport with the libido and may therefore influence it, augmenting or diminishing desire. For instance, a history of sexual activity which has been hardly gratifying due to a deficiency of erection or to ejaculatory disturbance, often leads the Patient to a secondary lessening of desire, distancing himself from sexual activity more and more.
The limbic system has its internal connections and then links to other cerebral structures of the endocrine, constituted from the hypothalamus and the hypophysis. These release specific substances (releasing factors, gonadotrophins) which modulate the production of testosterone in the testicle. Testosterone and its metabolism are considered the principal hormones governing the maintenance of sexual desire in the human species.

From examinations of these necessary conditions of the purely biological nature of desire, one sees a marked connection in the primitive area of our brain like the limbic system and the cortical systems is given the highest level of thought (memory and conception). One cannot but intuit that desire does not depend exclusively on physical factors.

Clinical experience teaches us that other than a good functioning of our hardware system, we also need a good software which contains the following elements: the right dose of physical and mental wellbeing, a satisfying relationship of seduction and complicity with a partner, a good social life allowing for space to live our emotions, friendship and free time, as well as a lifestyle that adequately balances work and rest. In other words, we need a good quality of life..
These important environmental elements are "digitalised", that is, translated in a biochemical language which our hardware understands from numerous substances in our brain defined as neuromediators and neurohormones. These make a real ring of conjunction with the "application system" of hypophysar and testicular hormones.

The diagnosis, therefore, not only aims at a search for the organic, pathological elements (endocrine pathology, the taking of drugs, hypogonadism, etc), but must also recognise a more holistic evaluation of the Patient and his quality of life.

As regards therapy, in cases where the hormonal climate is not adequate, restoring a good level of hormones of the organism is brought about; this can be done by gonadotrophin LH or androgens or other medication which produces the action of a hypothalamic "releasing factor"(GnRH) administered through the nose. If the deficiency of desire carries a elevated level of endogenic oppioids, the substances which are produced following stress and which protect us from it, or an excessive level which inhibits sexual functioning, one may evaluate the opportunity of pharmacological therapy meant to reduce such actions.

If the lack of libido depends on other concomitant pathologies, the cure of such pathologies will restore normal sexual desire. For example, in the case of pituitary adenome which produces an abnormal quantity of prolactin, the use of specific therapy which cures the adenoma allows for the normalisation of the libido; in cases of the reduced function of the thyroid, specific hormonal correction will augment the lack of desire, etc.