Transcranial direct current stimulation in obsessive-compulsive disorder: emerging clinical evidence and considerations for optimal montage of electrodes

Abstract

Background: Neuromodulation techniques for obsessive-compulsive disorder (OCD) treatment have expanded with greater understanding of the brain circuits involved. Transcranial direct current stimulation (tDCS) might be a potential new treatment for OCD, although the optimal montage is unclear.

Objective: To perform a systematic review on meta-analyses of repetitive transcranianal magnetic stimulation (rTMS) and deep brain stimulation (DBS) trials for OCD, aiming to identify brain stimulation targets for future tDCS trials and to support the empirical evidence with computer head modeling analysis.

Methods: Systematic reviews of rTMS and DBS trials on OCD in Pubmed/MEDLINE were searched. For the tDCS computational analysis, we employed head models with the goal of optimally targeting current delivery to structures of interest.

Results: Only three references matched our eligibility criteria. We simulated four different electrodes montages and analyzed current direction and intensity.

Conclusion: Although DBS, rTMS and tDCS are not directly comparable and our theoretical model, based on DBS and rTMS targets, needs empirical validation, we found that the tDCS montage with the cathode over the pre-supplementary motor area and extra-cephalic anode seems to activate most of the areas related to OCD.

Keywords: computer-based modeling; non-invasive brain stimulation; obsessive–compulsive disorder; repetitive transcranial magnetic stimulation; transcranial direct current stimulation.

Figures

Figure 1

Flow chart or assessed studies in our review, according to PRISMA guidelines.

Figure 2. Estimated current flow for various transcranial direct current stimulation electrode configurations

These montages were optimized to achieve maximal stimulation intensities on the following bilateral targets (numbers indicate MNI coordinates): (A, B) inferior ventral striatum (±9, 9, −8); (C) ventral putamen (±20, 12, −3); (D) orbitofrontal cortex (±24, 58, −1); (E) supplementary motor area (±15, 17, 61). (B) The result from an individual head model using the inferior ventral striatum as the target. First column indicates locations of anode (dark red) and cathode (dark blue). For case (A) and (B), the anode is extra-cephalic. Stimulation here was 2 mA through small, ‘high-density’ electrodes. Axial, coronal and sagittal slices pass through the target (cyan circle). Color indicates intensity of electric field relative to the maximum value (same value for each row, shown above the slices).