Trophic Factors in Brain Aging and Disease

TLDR: To understand the quantitative alterations in the brain of patients with these disorders, it is necessary to define the extent to which normal individuals demonstrate alteration in the number of neurons, in microscopic pathology, and in neurotransmitter metabolism during the aging process.

Abstract: Success in treating and preventing infection and vascular disease has led to a significant increase in the number of people over the age of 65. This increase in the elderly population has focused attention on normal changes of the aging brain and the chronic disorders that may develop during the aging process. Clearly, such disorders are not inevitable consequences of aging, but they are present to a greater extent in aged individuals. The two common conditions which fall into this category are parkinsonism and Alzheimer’s disease. Both of these devastating diseases of the nervous system are degenerative disorders of unknown origin. In each, multiple etiologies, including viral or immunologic causes, have been implicated but never proven. Both conditions reflect pathologic changes in relatively limited pathways within the central nervous system. In Alzheimer’s disease and, to a much lesser extent, Parkinson’s disease, changes are noted which are known to occur in healthy older individuals. Thus, both conditions may represent accelerated aging of specific neuronal pathways. In order to understand the quantitative alterations in the brain of patients with these disorders, it is necessary to define the extent to which normal individuals demonstrate alterations in the number of neurons, in microscopic pathology, and in neurotransmitter metabolism during the aging process.