The objective of the study is to compare the efficacy of intranasal oxytocin versus intranasal placebo to improve symptoms in schizophrenia patients who have residual symptoms despite being on adequate treatment with antipsychotic medication.

Schizophrenia patients treated with even the best currently available antipsychotic drugs continue to experience significant symptoms. There is a strong need for better treatments including treatments that can safely be given as adjunct to current antipsychotics in order to improve overall efficacy of treatment. Oxytocin is a neurohypophyseal peptide best known for its role as a neurohormone involved in parturition and lactation. In addition to these well established peripheral effects, there is a compelling body of converging evidence indicating that oxytocin plays a critical role in the regulation of a number of diverse centrally-mediated behavioral and cognitive processes that are highly relevant to Schizophrenia, including social attachment and memory , (see Argiolas and Gessa 1990; McCarthy and Aaltemus 1997).Furthermore, several lines of research suggest that oxytocin receptors may be an important target for development of novel treatments for schizophrenia. Oxytocin and its receptors exist in several areas of the brain which have been heavily implicated in the pathophysiology of schizophrenia, such as the nucleus accumbens and the hippocampus, (Van Leeuwan et al 1985). Oxytocin administered peripherally inhibits dopamine transmission in the mesolimbic pathway (Sarnyai 1992) et al, 1990). Antipsychotics have been found to elevate the secretion of oxytocin in rats (Uvnas-Moberg et al 1992a) suggesting that endogenous oxytocin may play a role in the therapeutic effects of antipsychotic drugs. Each subject will be enrolled for 6 week treatment period after a screening phase Study procedure involves weekly clinic visits as an outpatient. Forty patients will be randomly assigned to either 40 IU oxytocin twice daily or vehicle placebo. After 3 weeks, treatments will be crossed over such that subjects that received oxytocin will receive placebo and vice versa. The study ratio is 1:1. Dose of oxytocin is based upon previous studies in humans showing improvement in schizophrenia related changes in behavior and brain function (Kosfeld et al, 2005; Kirsch 2005; Heinrich M 2003). The total study duration for each individual subject will be approximately 7 weeks, which includes up to 7-day screening period, a baseline (randomization) visit, three week treatment period, 1 week washout, baseline, and three weeks cross over treatment.