THE BEHAVIORAL-EFFECT OF M-CHLOROPHENYLPIPERAZINE (MCPP) AND METHYLPHENIDATE IN FIRST-EPISODE SCHIZOPHRENIA AND NORMAL CONTROLS

Although there has been renewed interest in the serotonin (5-HT) syste m in schizophrenia, direct evidence for 5-HT dysfunction is limited. T his study compares the responses of m-chlorophenyl-piperazine (mCPP), a 5-HT agonist, in first-episode schizophrenia and a known psychotogen ic dopamine agonist, methylphenidate. Eighteen patients experiencing t heir first episode of psychosis and eight healthy controls received me thylphenidate (0.5 mg/kg) and mCPP (0.1 mg/kg) intravenously. Behavior al assessments were done before and after the procedure, and a peak re sponse to each agent tons rated. Methylphenidate, but not mCPP, produc ed psychotic symptoms in patients. mCPP did decrease anxiety, hallucin ations, and anger and increased agitation, somatic concern, and impair ed understanding. Both agents had limited effects on controls. In conc lusion, unlike methylphenidate, mCPP did not produce psychotic symptom activation in schizophrenic patients in, and its effects appeared to be nonspecific. (C) 1997 American College of Neuropsychopharmacology.