Abnormal nonlinear Brain-Heart interactions in major depressive disorder: Evidence from Resting-State EEG and ECG.

OBJECTIVE

Major depressive disorder (MDD) disrupts the interactions between the brain and heart, yet the underlying mechanisms remain poorly understood. This study aims to investigate the abnormal nonlinear brain-heart interactions in MDD from a nonlinear perspective.

METHOD: Resting-state EEG and ECG signals were recorded from 38 MDD patients and 32 healthy controls. Convergent cross mapping (CCM) was used to explore the bidirectional interactions between EEG oscillations and heart rate variability (HRV). Pearson correlation assessed the relationship between abnormal brain-heart interactions and clinical symptoms. Feature ranking identified the key brain-heart interactions features for MDD.

RESULTS

MDD patients showed significantly attenuated heart-to-brain interactions in the high δ and θ bands, indicating a disrupted bottom-up interoceptive information flow. Heart-to-high δ interaction negatively correlated with the HAMD-24 score (r = -0.500, p = 0.008), linking impaired heart-to-brain interactions with depression severity. HRV control analysis confirmed that the impairment in heart-to-high δ interactions was associated to depression severity, not to autonomic dysfunction. Feature ranking emphasized the critical role of heart-to-brain interactions in low-frequency EEG oscillations.

CONCLUSION

Abnormal heart-to-brain interactions play a substantial role in the pathophysiology of depression.

SIGNIFICANCE: These findings highlight the importance of brain-heart dynamics in MDD and provide new insights into its underlying physiological mechanisms.