[Neuromediators in the brain of the aged].

From a review of the literature it appears that only dopaminergic and cholinergic deficiencies are well established in the elderly. Other changes, still awaiting description and confirmation, are likely to consist of deficiency, overfunctioning or complex imbalance depending on the system involved. They will probably show that ageing of the brain begins at an early stage in life and that there is a need for considering not only very old people but transformation extending from birth to death. Meanwhile, studying cerebral mediators in healthy elderly subjects is a necessary prerequisite to studies of the brain in old patients with neuropsychiatric disorders.