The Pharmacology of Tardive Dyskinesias

The activity of dopamine at certain striatal dopamine receptors is related to the appearance of tardive dyskinesias in man. By analogy to Huntington's chorea and L-dopa-induced dyskinesias in parkinsonism, it appears that tardive dyskinesias are related to increased responsiveness of dopamine receptor sites as a result of neuroleptic-induced denervation hypersensitivity. It has been demonstrated that anticholinergic drugs worsen tardive dyskinesias in patients who have this disorder. It also appears that anticholinergic drugs decrease the threshold for tardive dyskinesias and thereby increase the incidence of this disorder. This implies that centrally active anticholinergic agents should not be used as a routine adjunct to neuroleptic therapy.