Some patients with tardive dyskinesia fit the cholinergic-dopaminergic
imbalance theory, but some do not. In an attempt to study his heterogeneity
further, the authors measured the responses of 10 patients with tardive
dyskinesia to intravenous challenge doses of drugs that facilitate or
inhibit acetylcholine transmission (physostigmine or benztropine,
respectively). They then measured the response of these patients to an open
outpatient deanol trial. They found that the responses of half of the
patients followed the classic theory, 2 responded paradoxically, and 3
responsed inconsistently. They suggest that there is a subgroup of tardive
dyskinesia patients who fit the theory but that more research is needed to
identify the subgroups who do not.Abstract Teaser