Evaluation of Autonomic Nervous System, Saliva Cortisol Levels, and Cognitive Function in Major Depressive Disorder Patients

Table 3

Results of heart rate variability (HRV) in time domain and frequency domain analysis from ECG recording.

Domains	Control group	MDD group	value
	Mean ± SEM	Mean ± SEM
Mean HR (beat/min; BPM)	73.48 ± 2.01	87.42 ± 3.17	0.0045
SDHR	5.49 ± 0.46	11.67 ± 1.65	0.0017
Mean NN (ms)	0.87 ± 0.02	0.73 ± 0.05	0.0286
SDNN (ms)	68.66 ± 0.52	56.52 ± 1.04	<0.0001
HF (Hz)	0.63 ± 0.02	0.40 ± 0.03	<0.0001
LF (Hz)	0.36 ± 0.02	0.60 ± 0.03	<0.0001
LF/HF (Hz)	0.64 ± 0.08	1.77 ± 0.17	<0.0001

Note. The time domain analysis of HRV showed both mean HR and SDHR in the MDD group was significantly higher than the control group whereas MDD showed a significantly lower value of mean NN and SDNN when compared with normal participants. For frequency domain analysis, MDD patients displayed a significant decrease in HF value when compared with normal subjects. Contrastingly, MDD group showed significantly higher LF component value than participants in the control group. MDD patients consequently exhibited a significantly larger LF/HF ratio than that of the normal subjects; significant difference between the control group and MDD group ); high significant difference between the control and MDD group ; high significant difference between the control and MDD group ; HRV: heart rate variability; ECG: electrocardiogram; HR: heart rate; SDHR: standard deviation of heart rate; MDD: major depressive disorder; mean NN: mean of R-R intervals; SDNN: standard deviation of R-R intervals; HF: high frequency power; LF: low frequency power; LF/HF: low frequency/high frequency.