Fineberg NA, Cinosi E, Smith MVA, Busby AD, Wellsted D, Huneke NTM, Garg K, Aslan IH, Enara A, Garner M, Gordon R, Hall N, Meron D, Robbins TW, Wyatt S, Pellegrini L, and Baldwin DS
Background: Transcranial direct current stimulation (tDCS) is a non-invasive form of neurostimulation with potential for development as a self-administered intervention. It has shown promise as a safe and effective treatment for obsessive compulsive disorder (OCD) in a small number of studies. The two most favourable stimulation targets appear to be the left orbitofrontal cortex (L-OFC) and the supplementary motor area (SMA). We report the first study to test these targets head-to-head within a randomised sham-controlled trial. Our aim was to inform the design of future clinical research studies, by focussing on the acceptability and safety of the intervention, feasibility of recruitment, adherence to and tolerability of tDCS, and the size of any treatment-effect., Methods: FEATSOCS was a randomised, double-blind, sham-controlled, cross-over, multicentre study. Twenty adults with DSM-5-defined OCD were randomised to treatment, comprising three courses of clinic-based tDCS (SMA, L-OFC, Sham), randomly allocated and delivered in counterbalanced order. Each course comprised four 20-min 2 mA stimulations, delivered over two consecutive days, separated by a 'washout' period of at least four weeks. Assessments were carried out by raters who were blind to stimulation-type. Clinical outcomes were assessed before, during, and up to four weeks after stimulation. Patient representatives with lived experience of OCD were actively involved at all stages., Results: Clinicians showed willingness to recruit participants and recruitment to target was achieved. Adherence to treatment and study interventions was generally good, with only two dropouts. There were no serious adverse events, and adverse effects which did occur were transient and mostly mild in intensity. Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) scores were numerically improved from baseline to 24 h after the final stimulation across all intervention groups but tended to worsen thereafter. The greatest effect size was seen in the L-OFC arm, (Cohen's d = -0.5 [95% CI -1.2 to 0.2] versus Sham), suggesting this stimulation site should be pursued in further studies. Additional significant sham referenced improvements in secondary outcomes occurred in the L-OFC arm, and to a lesser extent with SMA stimulation., Conclusions: tDCS was acceptable, practicable to apply, well-tolerated and appears a promising potential treatment for OCD. The L-OFC represents the most promising target based on clinical changes, though the effects on OCD symptoms were not statistically significant compared to sham. SMA stimulation showed lesser signs of promise. Further investigation of tDCS in OCD is warranted, to determine the optimal stimulation protocol (current, frequency, duration), longer-term effectiveness and brain-based mechanisms of effect. If efficacy is substantiated, consideration of home-based approaches represents a rational next step., Trial Registration: ISRCTN17937049. https://doi.org/10.1186/ISRCTN17937049., Competing Interests: Declaration of Competing Interest Prof. Naomi Fineberg reports in the past 3 years she has held research or networking grants from the UK NIHR, COST Action, Orchard; accepted travel and/or hospitality expenses from the BAP, ECNP, RCPsych, CINP, International Forum of Mood and Anxiety Disorders, World Psychiatric Association; received payment from Elsevier for editorial duties and the Mental Health Academy for lecturing. Previously, she has accepted paid speaking engagements in various industry supported symposia and recruited patients for various industry-sponsored studies in the field of OCD treatment. She leads an NHS treatment service for OCD. She holds Board membership for various registered charities linked to OCD. She gives expert advice on psychopharmacology to the UK MHRA. She has participated in a WHO working group focussing on diagnosis and classification of obsessive compulsive or related disorders for the ICD-11. Eduardo Cinosi, Megan Smith, Amanda Busby, Ibrahim Aslan, Arun Enara, Kabir Garg, Matthew Garner, Robert Gordon, Natalie Hall, Nathan Huneke, Daniel Meron, David Wellsted, Solange Wyatt and Luca Pellegrini have no competing interests to declare. Prof. Trevor W Robbins provides consultancy for Cambridge Cognition and receives royalties for CANTAB. He offers consultancy for Arcadia, Takeda, Cassava, Greenfield Bioventures. He has received research grants from Shionogi and GlaxoSmithKline. He has received Editorial Honoraria from Springer, Nature and Elsevier. Prof. David S. Baldwin is a Medical Patron of Anxiety UK and was Clinical Advisor to the National Clinical Audit of Anxiety and Depression (2017–20). He receives an editorial fee from Wiley for his work with Human Psychopharmacology., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)