Bilateral electrodermal habituation-dishabituation and resting EEG in remitted schizophrenics

This study examined bilateral electrodermal responding, heart rate, and resting EEG in schizophrenics who were not psychotic at the time of testing. Twenty-four carefully diagnosed, remitted schizophrenics were compared to 22 medical outpatient controls. Subjects were exposed to 17 pure tones; the 16th tone differed in frequency and duration from the others. Prior to the tone series, subjects engaged in 2 minutes of respiratory maneuvers followed by a 5-minute rest period during which EEG was recorded. Consistent with past reports examining chronic, hospitalized patients, the schizophrenics divided evenly into responding and nonresponding groups and skin conductance responding was associated with a higher rate of spontaneous activity, elevated tonic conductance levels, and more responding during the respiratory exercises. When those responding in the control and schizophrenic groups were compared for number and amplitude of tone-elicited responses, no group differences emerged. There were no differences in dishabituation between these two groups. A variety of analyses failed to reveal any evidence of electrodermal or cerebral asymmetry. There were no differences between the two schizophrenic groups in measures of heart rate or resting EEG. However, consistent with other reports using hospitalized patients, the schizophrenics as a group produced less EEG alpha and more delta than the normal subjects. These results are consistent with the hypothesis that the electrodermal and EEG phenomena identified in psychotic, hospitalized patients represent stable traits characteristic of schizophrenia.