Neurochemical alterations during age-related anorexia.

Unexplained weight loss during the latter stages of aging is commonly preceded by a spontaneous diminution in food intake. Multiple etiologies of age-related anorexia in humans, ranging from social isolation to impaired gastrointestinal function, have been proposed. The observation of this phenomenon in older laboratory animals suggests that physiological changes play a significant causal role. A continually expanding body of information on the neurochemical control of food intake supports a contribution of altered neurochemistry to dysregulated feeding behavior. This review provides an update on the relationship between declining food intake during advanced age and physiological (specifically neurochemical) function. The complexity of the control of food intake as well as the variety of investigative methods used in this field of study render the identification of definitive causes difficult. Evidence presented here is evaluated and possible etiologic factors are suggested.