DEMENTIA AND PARKINSONS-DISEASE - BIOCHEMICAL AND CLINICOPATHOLOGICAL CORRELATIONS

  • 1 January 1985
    • journal article
    • research article
    • Vol. 141  (3) , 184-193
Abstract
Intellectual deterioration may be observed in Parkinson''s disease. Since it was reported that central cholinergic systems degenerate in senile dementia and Alzheimer''s disease, the activity of choline acetyltransferase (CAT) and the number of muscarinic receptors in various cortical regions were measured in 12 control subjects and 20 patients, and the biochemical results with were compared clinical and neuropathological data concerning the patients. Of the parkinsonian patients, 13 showed signs of intellectual decline (moderate in 8, severe in 5) and neuropathological examination of the cortex revealed in 10 cases a large number of Alzheimer type senile changes extending beyond the hippocampus. CAT activity was decreased in the cerebral cortex in every patient. The decrease was greater in intellectually deteriorated patients and in the group with numerous senile changes in the cortex. The number of muscarinic receptors was increased in patients that were treated with anticholinergic drugs until they died, but also in those who had not received these drugs, suggesting an underlying denervation hypersensitivity. In the caudate nucleus, however, neither CAT activity nor muscarinic receptor number was altered, indicating that the cortical cholinergic lesion was specific. Although in most cases dementia in Parkinson''s disease was of the Alzheimer type, the case of a demented parkinsonian patient in whom cortical CAT activity was severely decreased, in spite of the absence of cortical histopathological evidence characteristic of Alzheimer''s disease, suggests that a parkinsonian dementia different from the Alzheimer type exists. In Parkinson''s disease as in Alzheimer''s disease, the decrease in CAT activity in the cerebral cortex results from degeneration of the cholinergic neurons in the nucleus of Meynert which projects to the cortex. Although the severity of intellectual deterioration seems in relationship with the extent of degeneration, this could already begin before intellectual impairment is apparent.