Optimizing Transcutaneous Vagal Nerve Stimulation (tVNS) for Treatment of Major Depressive Disorder using functional near-infrared-spectroscopy (fNIRS) - based Functional Connectivity
Abstract
Introduction:
Neurostimulation techniques targeting specific brain networks are emerging as promising strategies for treating mental disorders. Transcutaneous vagus nerve stimulation (tVNS) has shown potential in modulating the default mode network, particularly in unipolar depression. This study presents a neuroanatomically and functionally guided tVNS intervention for early-stage unipolar depression.
Materials and Methods:
This pilot study involved 40 participants: 20 unmedicated individuals with early-stage unipolar depression and 20 healthy controls. tVNS was applied at 2Hz, 10Hz, 25Hz, and 40Hz in randomized order during resting-state conditions, with simultaneous neuroimaging using functional near-infrared spectroscopy (fNIRS). Whole-brain analysis (89 channels) was conducted to report significant changes in functional connectivity. Regions of interest (ROIs: right frontal pole, right anterior inferior temporal gyrus, and left precuneus) were identified based on functional MRI analyses from 457 early-stage depression patients in the Marburg-Münster Affective Disorders Cohort Study (FOR2107). These ROIs were used to study the effects of different stimulation parameters.
Results:
Significant overlap was observed between the ROIs affected by tVNS and those linked to early-stage major depressive disorder in the FOR2107 cohort. Functional connectivity (FC) increased in depressive patients following 10Hz tVNS, particularly in the right frontal pole, right anterior inferior temporal gyrus, and left precuneus, whereas no such increase was observed in healthy controls. Group-level results showed a clear advantage for 10Hz stimulation compared to other frequencies, although considerable inter-subject variation was noted. Post-stimulation effects during resting-state suggest potential mid- to long-term benefits beyond the immediate session.
Conclusion:
The findings indicate that unipolar depression patients respond differently to tVNS than healthy individuals. Key observations include: (1) altered neural reactivity in depressed patients, (2) greater efficacy of 10Hz stimulation compared to 25Hz, and (3) the potential for individualized tVNS treatments based on fMRI and fNIRS data. This approach could enhance the personalization and effectiveness of depression treatments.
Research Category and Technology and Methods
Translational Research: 12. Vagus Nerve Stimulation (VNS)
Keywords
Transcutaneous Vagal Nerve Stimulation (tVNS), Major Depressive Disorder, functional near-infrared-spectroscopy (fNIRS), Functional Connectivity
