Electrodermal Responsivity and Suicide Risk

To the Editor.—  Edman et al¹ reported that patients at the Karolinska Hospital, Stockholm, who had a history of "violent" suicide attempts were electrodermally hyporesponsive to repetitive acoustic stimulation. In fact, all had ceased to respond within ten stimulus presentations. Their results are in agreement with data from a previous study by Spiegel.²

Patients and Methods.—  In a series of studies of the electrodermal activity in 59 depressed patients at the University Hospital in Linköping, Sweden, and 59 normal controls matched for age and sex,^3-6 we were able to validate Edman and colleagues'¹ findings. Of the depressed patients, 16 had a history of a previous suicide attempt. According to DSM-III criteria, 15 (94%) of these patients were suffering from a major depressive episode. The subjects took part in a standard habituation experiment with 37 tone stimuli (1 kHz; 1 s; 90 dB above 0.0002 dyne/cm²