Serum Prolyl Endopeptidase Activities of Patients with Senile Dementia of the Alzheimer Type and of Those with Vascular Dementia.

Abstract

The serum prolyl endopeptidase activities of patients with senile dementia of the Alzheimer type (SDAT) and of those with vascular dementia (VD) were measured by a sensitive fluorometric assay. As a result, the prolyl endopeptidase activity of both SDAT patients (p<0.025) and VD patients (p<0.001) was found to be significantly lower than that of normal subjects, and this activity of VD patients turned out to be significantly lower (p<0.001) than that of SDAT patients. The correlation between serum prolyl endopeptidase activity and that of other serum enzymes was examined, and a significant correlation was found with creatine kinase activity (r=0.560, p<0.001). Judging from these observations, it seems possible that the brain disorders of the dementia patients may have affected the metabolism of skeletal muscles, which possibly resulted in the lowering of their prolyl endopeptidase activity. At present, there are very few markers available for physiological diagnosis to distinguish between SDAT and VD patients, and therefore, the measurement of serum prolyl endopeptidase activities of dementia patients seems to be beneficial.