Low risk to certain diseases in aging: role of the autonomic nervous system and calcium metabolism.

The low risk of aging Africans, as opposed to high risk of Caucasians, to certain major disorders, including Parkinson's disease, myocardial infarction, osteoporosis and fractures, some rheumatic diseases, and an overall reduced incidence of cancer, has not been explained. In this study it is proposed, firstly, that relative risk is determined by a common physiological mechanism in which ANS status and calcium metabolism play a central role; secondly, that distinctive features of this mechanism in Africans may be subtly increased vagal tone, relatively enhanced dopaminergic versus noradrenergic activity, and an efficient dopamine/vitamin D-parathormone, anabolic hormone regulation of bone metabolism, and cell calcium homeostasis; and thirdly, that the neuroendocrine-metabolic context determines the response to specific stimuli; consequently, 'risk' factors, as defined for particular disorders, are not universally applicable. Maintained dopaminergic activity, as proposed for Africans, coupled with low risk to certain disorders, confirms the experimentally demonstrated paramount importance of this neurotransmitter in retarding aging processes in animals. The neuroendocrine profile as defined for Africans is consistent with a potentially extended period of physical and mental competence and a conceivable shorter duration of involutionary decline.