A frontal-vagal network theory for Major Depressive Disorder: Implications for optimizing neuromodulation techniques

Area of Science:

• Neuroscience
• Psychiatry
• Cardiology

Background:

• Major Depressive Disorder (MDD) frequently co-occurs with cardiovascular disease.
• Depressed patients often exhibit elevated heart rate (HR) and reduced heart rate variability (HRV).

Purpose of the Study:

• To propose a frontal-vagal network model linking brain function to cardiovascular changes in MDD.
• To review neuromodulation studies targeting brain regions implicated in depression and their effects on HR/HRV.
• To explore the utility of the frontal-vagal network for understanding depression pathways and guiding neuromodulation.

Main Methods:

• Review of existing literature on MDD, cardiovascular comorbidity, and neuromodulation.
• Analysis of studies targeting key brain nodes like the dorsolateral prefrontal cortex (DLPFC) and subgenual anterior cingulate cortex (sgACC).
• Examination of vagus nerve (VN) stimulation effects.
• Presentation of a meta-analysis of Neuro-Cardiac-Guided Transcranial Magnetic Stimulation (NCG-TMS) studies.

Main Results:

• The proposed frontal-vagal network integrates brain and heart activity in MDD.
• Neuromodulation targeting specific brain regions impacts HR and HRV.
• NCG-TMS demonstrates consistent HR deceleration during frontal stimulation and acceleration during motor strip stimulation, supporting its role in target engagement.

Conclusions:

• Incorporating HR and HRV measurements is crucial for depression research, especially in neuromodulation studies.
• The frontal-vagal network offers a framework for individualizing neuromodulation treatments like rTMS.
• NCG-TMS shows promise as a method for assessing target engagement in neuromodulation therapies for depression.