Heart rate variability (HRV) is reduced in patients with Major Depressive Disorder (MDD). We examined the sensitivity of a new nonlinear parameter, the Complex Correlation Measure (CCM) in patients with depression. Two-minute ECG recordings at rest with eyes-closed were analyzed. CCM was higher (0.36±0.1) in control participants compared to MDD (0.29±0.1), indicating a decrease in temporal variability associated with decreased parasympathetic function (Cohen’s d = 0.7, p=0.0008). CCM also demonstrated a larger effect size than SD1 (Cohen’s d = 0.5, p =0.0005) and SD2 (Cohen’s d = 0.2, p = 0.015). These results highlight that depressed patients display a dampening of oscillations between parasympathetic and sympathetic input indicative of reduced functionality and increased risk of sudden cardiac death. CCM is a more sensitive measure of HRV, which provides additional information on HRV dynamics compared to SD1 and SD2 of the Poincaré plot distribution.
Jelinek, H.F., Khandoker, A.H., Quintana, D.S., Imam, M.H., Kemp, A.H. (2011). Complex correlation measure as a sensitive indicator of risk for sudden cardiac death in patients with depression. Computing in Cardiology, 38.