Tau-positive grains are constant in centenarians’ hippocampus

The influence of age on the prevalence of argyrophilic grain disease has been analyzed in the hippocampus from 29 centenarians. Argyrophilic grains were detected in 12 cases with Gallyas silver method, in 24 cases with anti-exon 10 (RD4) immunohistochemistry, in all the cases with a phospho-independent anti-tau (piTau) antibody and with a monoclonal antibody against Ser202 of the tau protein (AT8), suggesting a maturation of the grains. Ballooned neurons were found in the hippocampus of 12 cases in which grains were, on average, more abundant. Coiled bodies were found in 26, 15 and 13 cases respectively with piTau antibody, RD4 and Gallyas method. Cases with coiled bodies had a higher density of grains. The mean density of grains did not differ in the patients with or without dementia. The prevalence of tau-positive grains has been underestimated in the very old population. As neurofibrillary tangles, they appear to be a constant accompaniment of age but, contrarily to neurofibrillary tangles, do not seem to be strongly associated with dementia.