Protein and nucleic acid content in the aging human brain.

The frontal cortex, white matter, cerebellum, caudate nucleus, thalamus and putamen of human brains, ranging from 16 to 91 years, were assayed for protein and nucleic acids. In all these areas the protein content decreased by 5--15% between 30 years and 90 years-of-age. The nucleic acid content, however, did not show any significant change. During a post-mortem interval of 6--25 hours there was no significant decrease found in either the protein or the nucleic acid content of brain tissue.