Brain causality alterations in major depressive disorder treatment

Area of Science:

• Neuroscience
• Computational Psychiatry
• Biomarkers

Background:

• Major depressive disorder (MDD) lacks objective biomarkers for treatment selection and monitoring.
• Current treatments for MDD include pharmacotherapy and neurostimulation, but early prediction of response remains challenging.

Purpose of the Study:

• To investigate distinct alterations in directional brain connectivity patterns induced by pharmacological and neurostimulation treatments within the first week of therapy.
• To identify baseline brain connectivity differences between treatment responders and nonresponders in MDD patients.

Main Methods:

• Information theory-based causality analysis was applied to electroencephalography (EEG) recordings from 176 MDD patients.
• Directional information flow was quantified across 19 EEG channels in five frequency bands (delta, theta, alpha, beta1, beta2) at baseline and one week post-treatment initiation.
• Global (FLOW) and local (INFLOW/OUTFLOW) metrics were used to analyze brain connectivity patterns.

Main Results:

• Pharmacological treatment increased information transmission in the beta2 band, with right-hemisphere dominance.
• Neurostimulation treatment increased information flow in the delta band, originating from the left hemisphere.
• At baseline, non-responders to pharmacological treatment showed higher alpha band information flow, particularly right-to-left hemisphere transmission, compared to responders.

Conclusions:

• Pharmacological and neurostimulation treatments engage distinct neural oscillatory mechanisms within the first week.
• Elevated baseline alpha-band causal transmission may identify patients unlikely to respond to pharmacological treatment, suggesting alternative interventions.
• Phase-based causality metrics show potential as biomarkers for early treatment stratification and monitoring in MDD.