Heart rate variability in subthreshold depression and major depressive disorder

Area of Science:

• Cardiology
• Psychiatry
• Biomedical Engineering

Background:

• Major depressive disorder (MDD) and heart rate variability (HRV) relationship is established.
• Subthreshold depression (SubD) poses a risk for MDD but lacks HRV research.
• SubD presents significant societal challenges.

Purpose of the Study:

• Investigate HRV in SubD.
• Compare HRV in SubD, MDD, and healthy controls (HC).
• Identify HRV as a potential biomarker for early depression detection.

Main Methods:

• Compared resting state HRV in 128 MDD patients, 131 SubD individuals, and 222 HC.
• Assessed depression, anxiety, and sleep quality using PHQ-9, GAD-7, and PSQI.
• Utilized Kruskal-Wallis test, Spearman correlation, and logistic regression for analysis.

Main Results:

• HRV showed increasing trends across MDD, SubD, and HC groups.
• Standard deviation of the Poincaré plot perpendicular along the line of identity (SD2), standard deviation of all RR intervals (SDNN), and low frequency (LF) were top HRV indices correlated with symptoms.
• Lower HRV was linked to increased MDD risk; LF, SDNN, and SD2 showed associations between SubD and HC.

Conclusions:

• This study pioneers HRV exploration in SubD.
• HRV changes are observable in SubD, with indices lower than HC but higher than MDD.
• SDNN, LF, and SD2 show promise as early depression biomarkers.