Electrodermal activity in schizophrenia: A quantitative study using a short interstimulus paradigm

Background: Electrodermal activity in response to short interstimulus inter val (ISI) stimulation allows aspects of information processing to be examin ed, but such paradigms cause skin conductance responses (SCRs) to overlap. A signal decomposition method was developed and employed to score the overl apped SCRs. This is the first application of the method to the study of sch izophrenia. Methods: Electrodermal activity of 30 medicated patients with schizophrenia and 50 normal controls was obtained using a conventional auditory oddball paradigm with an ISI of 1.3 sec. Tonic skin conductance level (SCL), phasic SCRs, SCR temporal dynamics, and a range of SCR variables in response to t arget tones were examined Results: The schizophrenic group showed reduced response rate, proportion o f responders, SCR amplitude, rise time, peak latency, and steady-state resp onse amplitude over the trial compared with controls. There were no between -group differences in SCL or SCR onset time. Conclusions: The combined use of a conventional short ISI paradigm and the new SCP scaring method demonstrated new facets of electrodermal hyporeactiv ity in medicated patients with schizophrenia. The hyporeactivity could not be attributed to changes in tonic arousal or dysfunctions in peripheral sym pathetic nerve conductance. Biol Psychiatry 1999;45:127-135 (C) 1999 Societ y of Biological Psychiatry.