DIFFERENCES OF HEART RATE VARIABILITY IN FIRST-EPISODE DRUG-NAIVE ADOLESCENTS WITH MAJOR DEPRESSIVE DISORDER

초록

Objectives MDD is quite a common mental disorder affecting adolescents. Therefore, understanding the physiological mechanism of adolescent MDD has important clinical implications for this disorder. Heart rate variability (HRV) studies have observed differences between depressed and healthy comparison participants. In general, HRV is known to be decreased in MDD. Some studies concluded that HRV decrease persists even after remission of depression, whereas other studies reported increase of HRV after successful treatment of depression. However, little is known about HRV in adolescents with MDD. The goal of this study was to determine whether HRV is also decreased in adolescents with MDD relative to normal control group and whether HRV changed significantly after treatment of MDD in the adolescent group. Methods A total of 53 participants were recruited. We recruited patients (ages 13–18 years), who were diagnosed with MDD. We also gathered volunteers from the local community and high school. The participants in the control group have never been treated in psychiatry clinics before. The patients were drug-naïve at the time of the HRV measure. The participants were diagnosed using criteria of the DSM-IV -Text Revision. Subject symptom information for MDD was gathered using the Hamilton Depression Rating Scale (HDRS) and Children’s Depression Inventory (CDI) in all of the participants, including healthy control subjects. Once eligible to participate in our study, we conducted the HRV measure. Each child was individually examined in a quiet room in the supine position for three minutes. Results In time domain analysis of HRV, MDD group did not show a decrease of HRV compared with the normal control group. However, in frequency domain analysis, MDD group showed a decrease in normalized high frequency (HF norm) and an increase in normalized low frequency (LF norm); thus, the LF/HF ratio indicated an increase of sympathetic tone. Score of HDRS and CDI showed positive correlation with LF norm and LF/HF ratio and negative correlation with HF norm. There was no significant change in overall HRV parameters after treatment of MDD with antidepressant. Conclusions In the analysis of HRV of adolescent MDD group, increase of sympathetic tone was significant compared with normal control group. Increase of sympathetic tone might be a meaningful feature of adolescent depression.