Cardiac autonomic regulation is impaired in girls with major depression

We aimed to study short-term heart rate variability (HRV) as an index of cardiac autonomic control in never-treated major depressive disorder (MDD) adolescent patients using linear and nonlinear analysis.

We have examined 20 MDD girls and 20 healthy age-matched girls at the age of 15 to 18yr. The ECG was recorded in three positions: the 1st supine rest, orthostasis, the 2nd supine position. HRV magnitude was quantified by time and frequency-domain analysis (mean RR interval, SDRR, RMSSD, spectral powers in low [LF] and high frequency [HF] bands). In addition to linear measures, HRV complexity was assessed by nonlinear (symbolic dynamics) indices: normalized complexity index (NCI), normalized unpredictability index (NUPI), and pattern classification measures (0V%, 1V%, 2LV%, 2UV%).

HRV magnitude (RMSSD, SDRR, LF and HF powers) was significantly decreased in MDD group in a supine rest and after posture change. HRV complexity was significantly reduced (lower NCI) in the standing position. Pattern classification analysis revealed significantly higher 0V% and lower 2LV% in MDD group in supine position and orthostasis.

The HRV linear and nonlinear analysis revealed decreased magnitude and complexity of heart rate time series indicating altered neurocardiac regulation in girls with major depression without pharmacotherapy.