Somatostatin and neuropeptide Y immunoreactivity in Parkinson's disease dementia with Alzheimer's changes.

Somatostatin-like immunoreactivity (SLI) and neuropeptide Y-like immunoreactivity (NPYLI) were measured in postmortem brain tissue from 12 control patients and 13 demented Parkinsonian patients who had Alzheimer-type cortical pathology. Twenty-two cortical regions were examined. Significant reductions in cortical SLI were found in 17 regions, while significant reductions in cortical NPYLI were found in nine regions. The reductions in SLI were typically 50-60%, while NPYLI reductions were 20-30%. These findings are similar to those in Alzheimer's disease (AD) and are consistent with a previous report of a dissociation between reductions in SLI and NPYLI in Parkinson's disease (PD) with dementia.