Neuroleptic effects on autonomic activity in schizophrenia: Between-group and within-subject paradigms and comparisons with controls

Effects of fluphenazine on electrodermal activity (EDA) and heart rate (HR) were studied in patients with schizophrenia and normal control subjects du ring rest periods, presentation of innocuous tones, and a reaction time (RT ) task. Two types of analyses were used: (1) between-group analyses-patient s taking placebo were compared with patients taking fluphenazine and with c ontrol subjects using only data from the first test session; and (2) within -subject analyses-the same patients were tested when taking fluphenazine an d when taking placebo. Results showed higher resting EDA and HR and smaller increments to task performance In placebo patients than in control subject s. Fluphenazine attenuated EDA levels but not the tonic response. Fluphenaz ine attenuated the HR response but did not affect FIR level. Placebo patien ts were electrodermally hyporesponsive to the RT stimuli but not to simple tones. Fluphenazine markedly attenuated responsivity to simple tones but it attenuated responsivity less for RT stimuli. Testing medicated patients ma y thus produce misleading results with respect to many, but not all, purpor ted autonomic markers of diagnosis in schizophrenia studies.