Heart rate variability before and after treatment with electroconvulsive therapy.

It has been suggested that depression may be associated with decreased parasympathetic activity. Based on this work, we tested the hypothesis that treatment of depression with electroconvulsive therapy (ECT) would result in a relative increase in cardiac vagal (parasympathetic) activity. Changes in respiratory sinus arrhythmia, a marker of cardiac parasympathetic activity, were examined in nine patients with depressive episodes before and after ECT using spectral analysis. Hamilton Depression Rating Scale scores decreased significantly. In terms of the heart rate measures, RR interval tended to decrease and the amplitude of respiratory sinus arrhythmia decreased significantly following the course of ECT. This reduction in respiratory sinus arrhythmia contributed to the overall decrease in RR interval variability. Additionally, the magnitude of symptom improvement as measured by the Hamilton Scale correlated with the decrease in amplitude of the respiratory sinus arrhythmia. We report that treatment of depression with ECT was associated with a relative decrease in parasympathetic activity, in contrast to our initial hypothesis of a relative increase. This finding may not be related to the ECT per se but rather to the resolution of depression, as there was a significant correlation between the decrease in Hamilton Depression Rating Scale scores and decrease in parasympathetic activity. Further work is necessary to better understand the autonomic changes associated with depressive illness and the clinical risks and benefits associated with various treatment modalities.