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Aging brain
Age is a major risk factor for most common neurodegenerative diseases, including Mild cognitive impairment, Alzheimer's disease, cerebrovascular disease, Parkinson's disease and Lou Gehrig's disease. While much research has focused on diseases of aging, there are few informative studies on the molecular biology of the aging brain (usually spelled ageing brain in British English) in the absence of neurodegenerative disease or the neuropsychological profile of healthy older adults. However, research does suggest that the aging process is associated with several structural, chemical, and functional changes in the brain as well as a host of neurocognitive changes. Recent reports in model organisms suggest that as organisms age, there are distinct changes in the expression of genes at the single neuron level. This page is devoted to reviewing the changes associated with healthy aging.
==Structural changes==
Aging entails many physical, biological, chemical, and psychological changes. Therefore, it is logical to assume the brain is no exception to this phenomenon. Computed Tomography (CT) studies have found that the cerebral ventricles expand as a function of age, and this process is known as ventriculomegaly. More recent MRI studies have reported age-related regional decreases in cerebral volume. Regional volume reduction is not uniform; some brain regions shrink at a rate of up to 1% per year, whereas others remain relatively stable until the end of the life-span. The brain is very complex, and is composed of many different areas and types of tissue, or matter. The different functions of different tissues in the brain may be more or less susceptible to age-induced changes.〔 The brain matter can be broadly classified as either grey matter, or white matter. Grey matter consists of cell bodies in the cortex and subcortical nuclei, whereas white matter consists of tightly packed myelinated axons connecting the neurons of the cerebral cortex to each other and with the periphery.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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