Acceptability of active and sham home-based transcranial direct current stimulation in major depression: mixed methods qualitative analysis in a randomised controlled trial

Purpose: Transcranial direct current stimulation (tDCS) is a novel non-invasive brain stimulation therapy that is a potential treatment for major depressive disorder (MDD). Acceptability impacts patient preference, treatment adherence and outcomes, however, it has typically been assessed through measures of attrition, self-reported satisfaction levels, or adverse events. We sought to explore participant acceptability using structured questionnaires and individual interviews. Methods: Acceptability was assessed in a fully remote, multisite, double-blind, placebo-controlled, randomized superiority trial of a 10-week course of home-based tDCS for MDD. Questionnaires were conducted at baseline and at the 10-week end of treatment. Participants were 174 adults (120 women) with MDD in a current depressive episode of at least moderate severity. Active or sham tDCS was self-administered over 10 weeks with remote supervision at regular intervals. A thematic analysis was conducted. Results: Four themes were revealed: acceptability, ease of use, side effects, and trial participation. The themes indicated generally high acceptability of tDCS as a treatment of MDD in both the active and sham treatment groups. Some participants noted concerns about the technical functionality of the device and the impact of side effects. Conclusions: The first three themes are central to understanding participant perspectives of tDCS and its feasibility as a treatment option. In addition, the theme of trial participation highlights the value of participant support when introducing a new treatment, which may underscore treatment options in general. Furthermore, acceptability is a dynamic concept as participant views changed during treatment. Trial registration: NCT05202119, registered on 9th January 2022.