The orienting response in schizophrenia and mania

We examined skin conductance (SCR) and finger pulse amplitude response (PULSE) in 53 schizophrenic, 30 manic, and 28 control subjects to provide information on orienting response (OR) dysfunction in severe psychiatric disorders. SCR and PULSE to neutral and task-relevant tones were measured in acutely ill inpatients and normal control subjects on two occasions separated by a 3-week interval. There were no significant group differences in proportions of SCR and PULSE non-responders to neutral tones. PULSE frequency to task-relevant tones in both the schizophrenic and manic patients was lower than that for the control subjects in both OR sessions, but did not differ significantly between patient groups. Although PULSE frequency was inversely related to neuroleptic dose in the schizophrenia sample, reanalysis of unmedicated patients did not change our results. OR frequency to task-relevant but not to neutral tones exhibited test-retest reliability. Certain aspects of OR dysfunction may overlap in schizophrenia and bipolar disorder. Our failure to demonstrate excessive OR non-responding to neutral tones in schizophrenia patients is inconsistent with many previous studies but may be due to a high proportion of OR non-responders among the control subjects.