Neurobiological studies of transmitter systems in aging and in Alzheimer-type dementia

Dysfunction and death of specific neuronal systems are important processes occurring in aging and in Alzheimer's and in Parkinson's disease. The neuropathology and neurochemistry of some of the neuronal systems at risk in these settings are subjects of active research; the nature and consequences of these cellular pathologies have begun to be clarified. The availability of animal models (including aged monkeys, macaques with cholinergic deficiencies, and monkeys with MPTP-induced nigrostriatal pathology, all of which recapitulate certain features of human aging or disease) allow the opportunity to assess the efficacies of new pharmacotherapies, neural grafts, and trophic factors. These approaches can be monitored by behavioral testing and, in some instances, by in vivo imaging methods, which can in turn be correlated with morphologic and chemical analyses of brain. Demonstration of the efficacy of these procedures in nonhuman primates would have profound implications on the development of new therapies designed to alleviate the effects of aging and disease on the human brain.