Neuropeptides in Alzheimer's disease.

A large number of neuropeptides have been found in cortical neurons. They are therefore of interest in attempting to demonstrate selective vulnerability of different populations of neurons in Alzheimer's disease (AD). The most consistent neuropeptide deficit in AD is reductions in cortical concentrations of somatostatin. Lesser reductions in corticotropin-releasing factor, neuropeptide Y and substance P have been reported. Concentrations of both vasoactive intestinal polypeptide and cholecystokinin are relatively preserve. The morphologic correlate of reduced somatostatin concentrations in AD appears to be markedly distorted and reduced terminal fiber plexuses, rather than reduced numbers of neuronal perikarya. A large number of neuropeptides have been localized in senile plaques.