System identification of skin conductance response in depression - an attempt to probe the neurochemistry of limbic system.

Abstract

OBJECTIVE: Choice of antidepressant is a daily problem in clinical work. Clinical predictors of therapeutic response to antidepressants are not yet available. We explored the possibility of using a signal analysis of skin conductance response (SCR) in specifying the imbalances of the neurotransmitter systems in the brain. SUBJECTS AND METHODS: The method consists in application of the system identification theory in analyzing the regulation of SCR. Eleven short stories from the contemporary literature have been used to elicit emotional arousal in subjects. Participants were divided into two groups, a group of depressed patients (n=57), and a healthy control group (n=52). RESULTS: The resulting mathematical model of SCR revealed two feedback loops. Significant differences have been found between depressed patients and healthy subjects in the sense of stronger signals in both identified feedback loops in depression. We considered these results in the context of the data regarding: (i) the functional neuroanatomy of SCR, and (ii) the neurochemical characteristics of depression. CONCLUSION: The methodological approach that is still to be examined could be useful in prediction of response to a specific antidepressant.