Heart rate variability in patients with major depression.

This study compared cardiac autonomic modulation in physically healthy patients with major depressive disorder to that in mentally healthy heart transplant recipients and physically and mentally healthy comparison subjects by using a nonlinear measure and a conventional measure of heart rate variability. No significant differences in cardiac autonomic modulation were noted between the depressive group and the transplant recipients, but both of those groups had significantly lower mean values for heart rate variability measures relative to the healthy comparison subjects. The results support the hypothesis that cardiac autonomic imbalance (reduced vagal modulation) to the extent of cardiac neuropathy is present in depression.