Myelin proteins in aging human brain.

Autopsy material of 13 persons who died between 70 and 89 yrs old and of patients who died between 27 and 44 yrs old was studied. White matter of temporal, parietal, and occipital lobes was investigated using histological and biochemical methods. According to results of neuropathological studies, the material of aged patients was divided into two subgroups: (a) brains with vascular changes only and (b) patients with senile atrophy of Alzheimer type. Chemical changes found in all studied brain lobes included a mild decrease in Wolfgram protein content with reciprocal increase in large basic protein content, together with a marked decrease in myelin yield. The abovementioned chemical changes were almost identical whether they were only vascular changes or whether senile atrophy of Alzheimer type was also present. It seems, therefore, that the degeneration of vessels is the decisive factor in the pathogenetic mechanism of myelin lesions in the aged brain.