Real-world effectiveness of self-administered transcranial direct current stimulation (tDCS) for depression: A retrospective cohort study

Background: Flow FL-100 is a transcranial direct current stimulation (tDCS) device self-administered by users at home. The retrospective analysis examined real-world usage and effectiveness of Flow tDCS treatment using data from 14,726 users collected by Flow Neuroscience AB between 2020 and 2024. Methods: Self-reported user background information and Montgomery-Åsberg Depression Rating Scale Self (MADRS-S) scores up to week 50 of the treatment were analysed. Effectiveness metrics (remission, response, and relapse rates) were assessed at pre-treatment baseline followed by week 3, 6, 10, 15, 20, and 50. Repeated-measures ANOVA, post-hoc and between-subject analysis were used to examine the change in MADRS-S over time and the influence of user background factors. Outcomes: The reported mean MADRS-S score decreased from a moderate level before treatment to a mild level at week 10 and then plateaued thereafter. Response and remission rates increased between week 3 and week 10, then stabilised through to week 50. A repeated measures ANOVA and post-hoc test reveal statistically significant differences (p < 0.0001) in MADRS-S scores across multiple time points. Reduction in reported depressive symptoms was observed during the initial weeks of treatment, these levels were maintained throughout the subsequent weeks. User adherence and background factors were significantly associated (p ≤ 0.005) with changes in MADRS-S scores during the first 10 weeks of treatment. Interpretations: Users of self-administered Flow tDCS treatment reported a rapid initial improvement and long-term reduction of depressive symptoms. Observed variability in adherence and response across diverse user groups suggests potential benefits from personalised treatment protocols and support.