Brain Blood Flow Changes Elicited by Oxytocin in Volunteers With and Without Schizophrenia

Schizophrenia is a severely debilitating psychiatric disorder that afflicts approximately 1% of the population (American Psychiatric Association, 1994) and is a serious public health problem. The specific mechanism of schizophrenia remains unknown. Affective responsivity and adaptive social behaviors are fundamental impairments in people with schizophrenia. These features have a detrimental impact on function in many areas of daily life. Unfortunately, the brain mechanisms that underlie these problems are still not understood. This study will use positron emission tomography (PET) and regional cerebral blood flow (rCBF) measures to ascertain the timing (1.5 hour period) of OT action on absolute regional brain activity in schizophrenia (SZ) and healthy control (HC) subjects. Particular focus will be on the amygdala, ventral striatum, anterior hippocampus and hypothalamus (neural regions involved in affliative behavior). Subjects will be studied with intranasally administered oxytocin and placebo while at rest and while making judgments about emotional faces. This approach will tell us to what extent the amygdala and limbic system's physiological response to oxytocin is predictive of a subject's behavioral sensitivity to this neuropeptide. The elucidation of this information may have a significant impact on predicting functional outcome and novel drug treatments in schizophrenia. Functional magnetic resonance imaging (MRI) studies show that oxytocin modulates the amygdala's response during social and emotional decisions. When administered intranasally, OT may be beneficial for the treatment of negative symptoms in schizophrenia by enhancing a person's affiliative behavior and diminishing distrust. It is not, however, known to what extent intranasal oxytocin modifies regional neurotransmission and human brain metabolism. There are at present no studies in animals or humans specifically examining the time course action of OT on whole brain activity.