Electrodermal activation in first-episode psychotic patients and their first-degree relatives.

We hypothesized that electrodermal deviations evident in patients with schizophrenia would also be present in their biological relatives and examined the specificity of abnormal EDA to schizophrenia patients and their families. One hundred and thirty-five first-episode psychotic patients with either schizophrenia or other psychotic disorders; 104 non-psychiatric comparison subjects; 178 relatives of these subjects; and a comparison group of 61 patients with chronic schizophrenia had their EDA monitored while they listened to auditory stimuli. Electrodermal non-responding, regardless of the nature of the stimulus, was common to all patient groups and tended to run in families. However, non-responding did not differentiate the relatives of the psychotic patients from those of non-psychiatric subjects. Responders in both the chronic and first-episode schizophrenia patients showed an excessively high rate of non-specific fluctuations (NSFs), as did the first-degree relatives of the first-episode patients. Patients with major depression had more NSFs than normal, but significantly so only during one of the tone series. Their relatives, however, had a high NSF rate in both tone series. The results indicate that a high NSF rate may represent a psychophysiological marker of risk for schizophrenia and psychotic depression. Electrodermal non-responding is not specific to schizophrenia and is not likely to be useful as an indicator of genetic risk.