The effect of transcranial direct current stimulation (tDCS) on cerebellum in reduction of the symptoms of obsessive-compulsive disorder

Abstract

ABSTRACT Obsessive-Compulsive Disorder (OCD) is one disabling psychiatriccondition. Investigations reported theeffectiveness of trans-cranial direct current stimulation (tDCS) in regulatingorbito-fronto-striato-pallido-thalamic network activity in OCD patients. Inthese patients, hypo- or hyper-activity of different brain areas includingorbitofrontal cortex (OFC), pre-supplementary motor area (pre-SMA), cingulategyrus, putamen, thalamus, parietal cortex and cerebellum have been reported.Thepurpose of this study is determination the efficacy of three different tDCSprotocols and finding the best one to mitigate OCD symptoms. This study was a quasi-experimental research with pre-test-post-test and a one-month follow-up. Of thepatients that referred to Brain and Cognitive Clinic in Tehran, 40 OCD subjectswere randomly selected and assigned into four groups (three experimental groupsand one control group). Of the mentioned patients, those who scored 16 or aboveon the Yale-Brown obsessive-compulsive scale were chosen. tDCS was delivered overa period of 5 days at an intensity of 2 mA for 15 minutes twice a day. In the three intervention groups, tDCSwas delivered in one of the following electrode montages: (i) anode over theright cerebellum (O2) and cathode over the supplementary motor area (pre-SMA; c3/c4); (ii)anode over O2 and cathode over the left OFC (FP1); or (iii) anode over O2 and cathode over the left cerebellum (O1). The controlgroup received sham stimulation (anode over O2 and cathode over the left FP1). Analysisof covariance (ANCOVA) was used to evaluate the results. The results showed that two of the tDCS protocolsreduced OCD symptoms (P < 0.001). Data also revealed that the effect of theanodal stimulation of the O2 led to better outputs as compared to O1. .