In a placebo-controlled, double-blind crossover study of 14 male chronic schizophrenic patients, high doses of the opiate antagonist naloxone were given intravenously. Hallucinations measured on a verbal-report scale were significantly decreased after naloxone administration. The authors suggest that this apparent action of naloxone is mediated by central opiate receptors and that it may result from an interaction between central endorphin systems and central catecholaminergic neurons.
