Somatostatin and dementia in Parkinson's disease.

The concentrations of somatostatin in the cortex, hippocampus and caudate nucleus of subjects with Parkinson's disease were determined by radioimmunoassay. Somatostatin levels in the frontal cortex were significantly reduced in Parkinsonian subjects who were slightly or severely demented compared to controls and to non-demented Parkinsonians. Significant reductions were also observed in the hippocampus and entorhinal cortex of severely demented subjects.