Feasibility and acceptability of transcranial stimulation in obsessive\u2013compulsive symptoms (FEATSOCS): study protocol for a randomised controlled trial of transcranial direct current stimulation (tDCS) in obsessive\u2013compulsive disorder (OCD)

Eduardo Cinosi,Natalie Hall,Megan V A Smith ,Trevor W Robbins ,Kieran Chillingsworth,Ibrahim H Aslan ,Deela Monji-Patel,Daniel Meron,Nick Sireau,David S Baldwin ,David Adam,Robert C Gordon ,Roisin Mooney,Matthew Garner,David Wellsted,Kabir Garg,Nathan T M Huneke,Sonay Kucukterzi-Ali,Tim M Gale ,Arun Enara,Solange Wyatt,Joanne Mccarthy,Naomi Fineberg

doi:10.1186/s40814-021-00945-6

Abstract

BackgroundObsessive–compulsive disorder (OCD) is a neuropsychiatric disorder which often proves refractory to current treatment approaches. Transcranial direct current stimulation (tDCS), a noninvasive form of neurostimulation, with potential for development as a self-administered intervention, has shown potential as a safe and efficacious treatment for OCD in a small number of trials. The two most promising stimulation sites are located above the orbitofrontal cortex (OFC) and the supplementary motor area (SMA).MethodsThe aim of this feasibility study is to inform the development of a definitive trial, focussing on the acceptability, safety of the intervention, feasibility of recruitment, adherence and tolerability to tDCS and study assessments and the size of the treatment effect. To this end, we will deliver a double-blind, sham-controlled, crossover randomised multicentre study in 25 adults with OCD. Each participant will receive three courses of tDCS (SMA, OFC and sham), randomly allocated and given in counterbalanced order. Each course comprises four 20-min stimulations, delivered over two consecutive days, separated by at least 4 weeks’ washout period. We will collect information about recruitment, study conduct and tDCS delivery. Blinded raters will assess clinical outcomes before, during and up to 4 weeks after stimulation using validated scales. We will include relevant objective neurocognitive tasks, testing cognitive flexibility, motor disinhibition, cooperation and habit learning.DiscussionWe will analyse the magnitude of the effect of the interventions on OCD symptoms alongside the standard deviation of the outcome measure, to estimate effect size and determine the optimal stimulation target. We will also measure the duration of the effect of stimulation, to provide information on spacing treatments efficiently. We will evaluate the usefulness and limitations of specific neurocognitive tests to determine a definitive test battery. Additionally, qualitative data will be collected from participants to better understand their experience of taking part in a tDCS intervention, as well as the impact on their overall quality of life. These clinical outcomes will enable the project team to further refine the methodology to ensure optimal efficiency in terms of both delivering and assessing the treatment in a full-scale trial.Trial registrationISRCTN17937049. (date applied 08/07/2019).Recruitment (ongoing) began 23rd July 2019 and is anticipated to complete 30th April 2021.

Highlights

Obsessive–compulsive disorder (OCD) is a neuropsychiatric disorder which often proves refractory to current treatment approaches
Qualitative data will be collected from participants to better understand their experience of taking part in a Transcranial direct current stimulation (tDCS) intervention, as well as the impact on their overall quality of life
The acceptability of tDCS will be considered throughout the ascertainment ratio, willingness of clinicians to recruit to the study, and the numbers of patients citing tDCS as the reason for refusal (< 20%)

Summary

Introduction

Obsessive–compulsive disorder (OCD) is a neuropsychiatric disorder which often proves refractory to current treatment approaches. Transcranial direct current stimulation (tDCS), a noninvasive form of neurostimulation, with potential for development as a self-administered intervention, has shown potential as a safe and efficacious treatment for OCD in a small number of trials. With a lifetime prevalence of 2–3%, obsessive–compulsive disorder (OCD) represents a leading global cause of functional disability [1, 2]. Regardless of gender and culture, OCD typically has an early onset, follows a prolonged course, and is associated with significant reduced quality of life (QoL) and social and occupational impairment [3]. Chronic OCD is associated with substantial comorbidity and considerable disability. Whereas evidence-based treatments lead to symptomatic improvement and associated improved QoL [10], rates of incomplete recovery and treatment resistance are high: approximately 40% patients do not respond, and 50% need further treatment [4]. New treatments are needed to improve health outcomes [12, 13]

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