Electrodermally differentiated subgroups of anxiety patients. I. Automatic and vigilance characteristics.

A total of 32 anxiety patients (agoraphobia, panic syndrome, generalized anxiety syndrome) selected according to the DSM-III criteria were compared with 16 controls to determine distinguishing features of autonomic response patterns to a sequence of verbal and acoustic stimuli. In addition sensorimotor tasks were performed. The anxiety patients were classified into electrodermally stabile and labile subgroups on the basis of two reliably measurable psychophysiological parameters: the rate of electrodermal habituation to neutral stimuli and non-specific electrodermal activity. The electrodermally labile anxiety group was characterized by a high degree of variability in respiratory and pulse rate during the autonomic activation procedure. Within the control group the electrodermally labile subjects were characterized by a significantly higher pulse rate during the entire autonomic activation procedure. The reduced habituation capacity of the labile subgroup of anxiety patients compared to the controls was reflected in both retarded habituation and long durations of electrodermal responses to all verbal stimuli. This group also tolerated monotony; their performance did not drop during the 256 sensorimotor reaction time tasks and even exceeded the performance of the control group by the end of the test. The stabile anxiety subgroup had a significantly longer reaction time in all reaction time tasks than the labile subgroup of anxiety patients.