Late onset involuntary movements in chronic schizophrenia: relationship of 'tardive' dyskinesia to intellectual impairment and negative symptoms.

Intellectual impairment, negative symptoms, and medication history were assessed in chronic schizophrenic patients with and without abnormal involuntary movements (tardive dyskinesia). Patients with involuntary movements had received neither longer nor more intensive treatment with neuroleptics or anticholinergics. However, the presence or absence of involuntary movements was prominently associated with the presence or absence of intellectual impairment/negative symptoms; these features are characteristic of the defect state/type II syndrome of schizophrenia, in which structural abnormalities of the brain may be over-represented. The role of subtle organic changes in conferring vulnerability to the emergence of such involuntary movements should be re-evaluated.