[Electrodermal hypoactivity in depression: psychobiological marker or differential psychophysiologic disposition?].

Research about the dominating hypoactivity in electrodermal system in affective disorders led to the assumption that electrodermal activity (EDA) could be an important biopsychological trait in the etiology of depression. However, experimental results are contradictory. Some studies find nosological validity, other studies an influence of psychomotor status on EDA or correlations to clinical improvement, etc. Most of these results are based on laboratory conditions (habituation experiment with tones). The person-situation-environment interaction and their dynamic process regulation on electrodermal activity are neglected. Also lacking is a comparable description of nosology, psychomotor status and experimental design. After discussing the neuropsychological background of the habituation paradigm which led to the "traditional" assumptions of the correlation between electrodermal activity and depression, results of different samples are shown tested over years using always the same classification and experimental methods. None of our assumptions could be verified. Although low levels in SCL dominate, we could not find results of high sensitivity and specificity in contrast to controls. However we found differences in other, more complex experiments containing personality traits and reactions to emotional words. In a multi-level process-oriented stress paradigm of the success/failure type we found a delay in regeneration of psychological and electrodermal measures after failure. This results demonstrate that investigation in electrodermal activity needs more complex and process-oriented experimental designs. EDA probably has not the quality of a biological marker, but seen in the context of person and situation factors it differentiates depressed states.