==== Front Indian J Psychol MedIndian J Psychol MedIJPsyMIndian Journal of Psychological Medicine0253-71760975-1564Medknow Publications & Media Pvt Ltd India IJPsyM-40-39310.4103/IJPSYM.IJPSYM_112_18Letters to EditorComments on “Efficacy of Transcranial Direct Current Stimulation in the Treatment: Resistant Patients Who Suffer from Severe Obsessive-compulsive Disorder” Suhas Satish Banwari Girish 1Tharayil Harish M. 2Karia Sagar 3D’Cruz Migita M. Nagendrappa Sachin Andrade Chittaranjan 4Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India1 Department of Psychiatry, Dr. Ismail Polyclinic and National Medical Center, Dubai, UAE2 Department of Psychiatry, Government Medical College, Kozhikode, Kerala, India3 Department of Psychiatry, Lokmanya Tilak Municipal Medical College and General Hospital, Mumbai, Maharastra, India4 Department of Psychopharmacology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, IndiaAddress for correspondence: Dr. Satish Suhas, Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bengaluru - 560 029, Karnataka, India. E-mail: suhasedu@yahoo.inJul-Aug 2018 40 4 393 394 Copyright: © 2018 Indian Psychiatric Society - South Zonal Branch2018This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. ==== Body Sir, Najafi et al.[1] described a nonblind, uncontrolled evaluation of 15 once daily, 5 per week sessions of transcranial direct current stimulation (tDCS) in 42 patients with severe, treatment-resistant obsessive–compulsive disorder (OCD). We urge that readers view their results with considerable caution. The authors did not provide a complete operational definition of treatment resistance. They did not describe the clinical characteristics of the sample. They did not provide information about concurrent medications during and after the tDCS course. Their description of electrode positioning in the 10–20 electroencephalography system does not correspond with the anatomical sites they named. Their description of the inferential statistical procedures suggests that they had difficulties with interpreting the analysis. Unusually, there were no dropouts from among 42 patients in a 3-week trial with daily sessions and a 3-month follow-up. Finally, they obtained results that are at considerable variance with clinical experience. OCD is hard to treat, and an adequate clinical trial is suggested to require 2–3 months; attenuation of OCD ratings by 25%–35% is commonly set as the threshold for response.[234] Yet, Najafi et al.[1] found that the sample as a whole showed >50% response in just 2 weeks and >75% improvement at a 3-month follow-up. In fact, at the final assessments, the patients were almost in remission, a rare event in OCD research.[234] Such dramatic outcomes are especially difficult to understand because tDCS is a mild treatment that does not stimulate or inhibit the underlying cerebral cortex; it is merely a neuromodulator that facilitates or inhibits depolarization of the underlying cortex.[56] In this context, it must be recognized that OCD is believed to more involve not the cortex but subcortical structures such as the thalamus and basal ganglia and associated subcortical neurocircuits;[78] these are poorly targeted by tDCS.[56] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. ==== Refs REFERENCES 1 Najafi K Fakour Y Zarrabi H Heidarzadeh A Khalkhali M Yeganeh T Efficacy of transcranial direct current stimulation in the treatment: Resistant patients who suffer from severe obsessive-compulsive disorder Indian J Psychol Med 2017 39 573 8 29200551 2 Soomro GM Altman D Rajagopal S Oakley-Browne M Selective serotonin re-uptake inhibitors (SSRIs) versus placebo for obsessive compulsive disorder (OCD) Cochrane Database Syst Rev 2008 CD001765 3 Pittenger C Bloch MH Pharmacological treatment of obsessive-compulsive disorder Psychiatr Clin North Am 2014 37 375 91 25150568 4 Hirschtritt ME Bloch MH Mathews CA Obsessive-compulsive disorder: Advances in diagnosis and treatment JAMA 2017 317 1358 67 28384832 5 Nitsche MA Cohen LG Wassermann EM Priori A Lang N Antal A Transcranial direct current stimulation: State of the art 2008 Brain Stimul 2008 1 206 23 20633386 6 Brunoni AR Nitsche MA Bolognini N Bikson M Wagner T Merabet L Clinical research with transcranial direct current stimulation (tDCS): Challenges and future directions Brain Stimul 2012 5 175 95 22037126 7 Mulders AE Plantinga BR Schruers K Duits A Janssen ML Ackermans L Deep brain stimulation of the subthalamic nucleus in obsessive-compulsive disorder: Neuroanatomical and pathophysiological considerations Eur Neuropsychopharmacol 2016 26 1909 19 27838106 8 Gürsel DA Avram M Sorg C Brandl F Koch K Frontoparietal areas link impairments of large-scale intrinsic brain networks with aberrant fronto-striatal interactions in OCD: A meta-analysis of resting-state functional connectivity Neurosci Biobehav Rev 2018 87 151 60 29410103