Perisomatic granules of hippocampal CA1 neurons in Alzheimer's disease, pre-Alzheimer stage and Pick's disease: an overlooked pathological entity.

There is overall consensus that neuronal loss occurs selectively in vulnerable areas of the brain in Alzheimer’s disease (AD) compared to age-matched normal specimens. Significant and disease specific loss of hippocampal neurons is known to occur in CA1 neuronal subsets which appear to be more severely affected than other hippocampal subregions’. However, the cause of cell death in the hippocampus remains unknown. One possibility is that, in some neurons at least, the accumulation of tau protein in an aggregated fibrillar form (the neurofibrillary tangle-NFT) results in the demise of the cell, although the way tau filaments interfere with neuronal function is largely unknown. Other proposed mechanisms leading to cell death are oxidative stress or excitatory amino acid (EAA) receptor-mediated exitotoxicity2.