Comparative neurochemical investigation of tardive dyskinesia and neuroleptic-induced chronic parkinsonism.

Cerebrospinal fluid (CSF) homovanillic acid (HVA), cyclic adenosine 3', 5'-monophosphate (cAMP), and serum prolactin were measured in schizophrenic male patients with tardive dyskinesia (TD) and in those exhibiting the symptoms of chronic neuroleptic parkinsonism (P). The patients (nine TD and eight P) were chronic paranoid schizophrenics. Levels of HVA in CSF were found to be significantly higher in the TD group. Normal prolactin levels were observed in both groups and are indicative of tolerance developed in the hypothalamic tuberoinfundibular dopaminergic system.