HISTOPATHOLOGICAL AND IMMUNOHISTOCHEMICAL EVALUATION OF AGING CHANGESIN NORMAL HUMAN BRAIN

As age related changes in the brain have not been systematically studi ed in the Indian population though there is an impression that they ar e less frequent, we studied 52 brains collected at autopsy from indivi duals above the age of 60 yr. The incidence of senile plaques (SPs) an d neurofibrillary tangles (NFTs) together were found to increase with age from 21 per cent in the seventh decade to 33 per cent in the eight h decade and 54 per cent in the ninth decade, the increasing incidence of NFTs being statistically significant. The SPs were found both in t he hippocampus and frontal cortex while NFTs were seen only in the hip pocampus in non-demented aged individuals. In contrast, in the three e ases of Alzheimer's disease (\) AD studied, the NFTs and SPs were foun d in high density in both hippocampus and frontal cortex. By immunohis tochemistry, various morphological forms of SPs were found to have bet a amyloid protein consistently, while ubiquitin and phosphorylated neu rofilament occurred variably. More number of SPs could be labelled by amyloid immunostaining than by conventional silver stains. The NFTs co ntained ubiquitin and phosphorylated neurofilament protein as the anti genic components, both in AD and normal ageing. The incidence of age r elated changes and their antigenic character in the limited sample stu died from south India appears to be comparable to findings from the We st. Multicentric studies on a large sample derived from different ethn ic groups in India are needed to further evaluate these features.