Reversal by Levodopa of Cholinergic Hypersensitivity in Parkinson's Disease

Abstract

The neurologic manifestations of Parkinson's disease may be derived from an imbalance of the dopaminergic and cholinergic pathways in the central nervous system. Levodopa was found to decrease or block completely the hypersensitivity to cholinergic stimulation in Parkinson's disease as measured by the physostigmine test. Levodopa-treated patients whose neurologic manifestations were no longer aggravated by intravenous physostigmine did not benefit by the addition of standard anticholinergic drugs. Cholinergic hyperactivity in Parkinson's disease may be secondary to decreased brain dopamine.