Plasma prolactin and homovanillic acid as markers for psychopathology and abnormal movements after neuroleptic dose decrease

Plasma prolactin concentration (pPRL), plasma homovanillic acid concentration (pHVA), and symptomatology were measured in 24 male subjects with schizophrenia during maintenance haloperidol treatment. Fourteen subjects subsequently underwent 50 percent dose decreases under placebo- controlled, double-blind conditions. At baseline, a significant inverse correlation was found between pPRL and both tardive dyskinesia (TD) and 'thinking disorder'; pPRL was directly correlated with negative symptoms. No such relationship was found with pHVA. In the patients who underwent a dose decrease, no relationship was found between baseline pPRL or pHVA and any clinical variable after the decrease. These data do not support the use of baseline pPRL or pHVA as markers of central dopamine function subsequent to a neuroleptic dose decrease.