Concentration of cholecystokinin in cerebrospinal fluid is decreased in psychosis: relationship to symptoms and drug response.

1. Cholecystokinin (CCK) is a neuropeptide which is co-localized within some mesolimbic and mesocortical dopamine neurons. 2. CCK resembles an antipsychotic drug in some pharmacological and behavioral tests. 3. Levels of CCK in the cerebrospinal fluid (CSF) are reduced in eleven drug-free schizophrenics in comparison with six controls. 4. Schizophrenic males have lower CSF CCK levels than females. 5. Rapidity of antipsychotic response to haloperidol appeared to be inversely related to drug-free baseline CSF CCK levels.