[Classical and ultrastructural neuropathology of aging processes in the human: a critical review (author's transl)]

Although the primary interest in the course of studies on aging is focused on problems of function, morphology has an important role to play as a marker and as a control. Processes concomitant with brain aging are multiple and diverse. They ought to be correlated individually with functional changes. Statistical problems in population sampling for reference morphological studies are difficult. Bias is often a consequence of unstated underlying theories (Brain aging: a physiological process v. one of many pathological processes). Morphological criteria do not allow close application of animal models to aging problems in the human. The review considers the following lesions: 1. Brain shrinkage; 2. Neuronal loss; 3. Alterations in the outline of neurons; 4. Lipofuscin accumulation; 5. Corpora amylacea; 6. Senile plaques and amyloid deposits; 7. "Neurofibrillar degeneration"; 8. "Granulovacuolar degeneration"; 9. Hirano bodies. Vascular changes and their consequences are not considered. Lesions in the first group (1 to 5) are interpreted as non-specific and non-specifically correlated with aging; their correlation with functional loss is low. Lesion in the second group (6 to 9), on the contrary, are strongly correlated with each other and with dementia; they are interpreted as characteristic, not of aging itself, but of a widespread pathological condition: Alzheimer's disease sensu lato. A current line of research involves the hypothesis of a viral origin of this condition.