Huntington's disease: treatment with muscimol, a GABA-mimetic drug.

Muscimol, a gamma-aminobutyric acid (GABA) analogue that exerts potent and specific agonist effects on GABA receptors, was administered orally to 10 patients with Huntington's disease. In this double-blind study, muscimol treatment did not result in improvement in these patients' motor or cognitive functions. However, muscimol administration did ameliorate chorea in the most severely hyperkinetic patient, and it was associated with the appearance of dystonic features, electroencephalographic changes, and behavioral alterations in some patients. These latter observations support a functional relationship between GABA-ergic activity and the genesis of both systonia and EEG abnormalities in humans. The therapeutic failure of muscimol indicates that the GABA disturbances in Huntington's disease does not alone account for the clinical features of this disorder.