Effects of transcranial direct current stimulation for treating depression: A modeling study

Area of Science:

• Neuroscience
• Computational modeling
• Medical engineering

Background:

• Transcranial direct current stimulation (tDCS) targeting the left dorsolateral prefrontal cortex (lDLPFC) is a common treatment for major depressive disorder (MDD).
• The impact of various tDCS protocols across the entire frontal lobe, particularly in large patient cohorts, remains under-investigated.

Purpose of the Study:

• To computationally model the electric field (EF) distribution of different tDCS protocols in 20 frontal regions.
• To compare EF distribution in healthy individuals and MDD patients using 38 head models.
• To evaluate the efficacy of seven bipolar and two multi-electrode 4x1 tDCS protocols.

Main Methods:

• Utilized 38 head models from structural MRI scans of 19 healthy adults and 19 MDD patients.
• Applied computational modeling to simulate tDCS-induced electric fields (EFs) across 20 frontal regions.
• Assessed seven bipolar and two multi-electrode 4x1 tDCS stimulation protocols.

Main Results:

• Bipolar tDCS montages produced comparable EF strengths in both the lDLPFC and medial prefrontal cortex (MPFC).
• EF cortical maps exhibited variability based on stimulation parameters but were similar between healthy controls and MDD patients.
• Multi-electrode 4x1 tDCS protocols resulted in more localized, though weaker, EF effects.

Conclusions:

• Excitability changes in the MPFC, alongside lDLPFC stimulation, should be considered for the clinical effectiveness of bipolar tDCS in MDD.
• Anatomical differences in MDD patients are unlikely to significantly impact tDCS current flow.
• Personalized computational modeling can enhance the precision of tDCS cortical targeting, with future research recommended to differentiate lDLPFC vs. MPFC contributions to therapeutic outcomes.