Efficacy of pre-supplementary motor area transcranial direct current stimulation for treatment resistant obsessive compulsive disorder: A randomized, double blinded, sham controlled trial

Clinical advances in obsessive-compulsive disorder: a position statement by the International College of Obsessive-Compulsive Spectrum Disorders

“…The SMA and OFC are key targets. A randomized sham-controlled trial (n = 24 treatment-resistant OCD subjects) demonstrated efficacy for anodal tDCS administered over bilateral pre-SMA and cathodal tDCS over right supraorbital regions (Gowda et al, 2019). However, another randomized crossover trial (n = 12) found clinical improvement with cathodal tDCS over pre-SMA, while anodal tDCS was ineffective (D'urso et al, 2016).…”

Could Transcranial Direct Current Stimulation Join the Therapeutic Armamentarium in Obsessive-Compulsive Disorder?

“…In fact, radiological studies have suggested abnormalities within a cortico-basal ganglia-thalamo-cortical loop that includes orbitofrontal-prefrontal areas, basal ganglia, thalamus, but also cerebellum, anterior cingulate cortex, insula, and temporal, parietal, and occipital regions [1,4]. In some of the studies that have adopted functional neuroimaging techniques, OCD was associated with abnormal activity in the orbitofrontal cortex (OFC), supplementary motor area (SMA), pre-SMA, and cerebellum [2,[6][7][8][9][10]. Therefore, one may hypothesize that improving obsessive-compulsive (OC) symptoms could be possible by targeting these cerebral areas.…”

“…tDCS literature in the context of OCD includes case reports, open-label studies, and few randomized controlled trials [2,[6][7][8][9][10]. Assessment included OC symptoms, by means of the Yale-Brown Obsessive and Compulsive Scale (YBOCS), as well as other comorbidities (i.e., anxiety and depressive symptoms).…”

“…Although interesting, the results are limited by the absence of sham intervention. Another randomized parallel-arm sham-controlled trial in 25 SSRI-resistant medicated OCD patients documented beneficial clinical effects, following five consecutive days of anodal tDCS over the left pre-SMA (two 20-min sessions per day, current intensity: 2 mA, electrodes size: 35 cm 2 , cathode over right supra-orbital area) [9]. Beneficial tDCS effects documented in the two abovementioned studies might be due to the modulation of what is known as "the response inhibition", a key function of the pre-SMA, and by doing so tDCS could have enhanced patients' capacity to suppress unwanted thoughts and behaviors.…”

“…The inter-study difference in anodal effects might be due to the difference in tDCS montage (including cephalic vs. extracephalic reference), cohorts' characteristics, sample size, and the presence/absence of sham condition. Interestingly, the right OFC might not be an inert reference, and therefore, it is not possible to formally eliminate effects emerging from cathodal stimulation of this area [9]. One may also wonder how bilateral cathodal and anodal tDCS over the pre-SMA could lead to significant clinical improvement.…”