['To determine if there were differences in CSF-TRH concentrations among several acute major psychiatric disorders and to investigate the effects of antipsychotic treatment on CSF-TRH levels.', 'CSF-TRH concentrations were measured in 62 psychiatric inpatients during an acute phase of illness after a drug-free period. CSF-TRH measurements were repeated in 14 of these patients after 4 weeks of antipsychotic treatment.', 'Post-hoc tests (Tukey HSD) revealed significant differences among patients with schizoaffective disorder and both schizophrenia (P<0.03) and major depression (P<0.01). There were no significant differences between pre and posttreatment levels of CSF-TRH in the 14 patients treated with conventional agents for 4 weeks (1.54 pg/ml vs. 1.47 pg/ml). However, patients with a reduction in CSF-TRH concentration had a significantly better symptom response measured by the Brief Psychiatric Rating Scale (BPRS) positive factor (61% in six subjects) vs. those who had an increase in posttreatment CSF-TRH (29% in eight subjects; t=2.2; d.f.=12; P<0.04).'] Do cSF thyrotropin-releasing hormone concentrations differ in patients with schizoaffective disorder from patients with schizophrenia or mood disorders?