In my previous post, I reviewed recent meta-analyses about the effectiveness of tDCS administered in clinical settings for treating depression. Click here to read that post.
Based on the effectiveness, safety profile, and relatively low cost of treating depression with tDCS, more companies are manufacturing and selling home-based tDCS devices. These devices are typically quite different from the more expensive devices used by researchers in clinical settings. A relevant concern is whether home users can effectively and safely operate a home device and if they can understand where to place the electrodes to ensure effective treatment of depression. Although few studies have been published regarding the effectiveness of these devices, the use of home-based devices increased during the pandemic and for those who cannot complete daily treatments at a clinic.
As of May, 2023, over 17 clinical trials, and many other non-clinical studies, have been published on the use of home-based tDCS devices for treating other conditions, such as for treating pain. Kumpf and colleagues published a 2023 review of research on home-based devices for treating major depressive disorder (the first such study was published in 2018) and to present results of a randomized controlled trial of home-based treatment.
In the trial, 16 subjects each were assigned to tDCS or sham (placebo) treatment groups. All subjects completed a minimum of 30 TDCS sessions over 6 weeks using the F3/F4 montage, 30-mins daily at 2 m/A. Those in the sham group felt electrical stimulation during ramp-up and ramp-down times to simulate actual treatment. All subjects had been diagnosed with major depressive disorder, and some subjects were taking anti-depressant medication or receiving psychotherapy. Only 11 subjects completed the study due to dropouts from receiving burns from the device.
There were no significant differences between treatment and sham groups for depression reduction at the end of the 6-week treatment and at a follow-up assessment at 10 weeks. Both groups experienced symptom reduction, which points to a placebo effect.
Takeaway: due to the small number of people who completed the trial, the results tell us very little. The number of burns experienced by users calls in to the question the safety of the device chosen for the study. It further highlights concerns with providing home-based treatments to severely depressed individuals who may struggle with proper use of the equipment.
Citation: Kumpf, U., Palm, U., Eder, J., Ezim, H., Stadler, M., Burkhardt, G. Dechanstreiter, E., & Padberg, F. (2023). TDCS at home for depressive disorders: An updated systematic review and lessons learned from a prematurely terminated randomized controlled pilot study. European Archives of Psychiatry and Clinical Neuroscience, 1-18. https://doi.org/10.1007/s00406-023-01620-y.
A single-blind study investigated the effect of home-based tDCS treatment on major depressive disorder. All participants were diagnosed with major depressive disorder, and all took an anti-depressant (escitalopram) during the study. Twenty-nine participants each were assigned to treatment and sham (placebo) groups. However, 9 participants in the treatment group and 4 in the sham group dropped out before completing the study. Participants used a home-based TDCS device once daily for 30 mins/day for 6 weeks. Those in the treatment group received 2 m/A of current during treatments; those in the control group received current only in 30-second ramp-up and ramp-down periods. Electrodes were placed in the F3/F4 positions. At two-week intervals, participants completed objective and subjective depression and mental status assessments at the hospital.
Participants in both groups experienced improvements in depression scores over the 6-week treatment period. Scores on only one of the depression inventories differentiated those in the treatment group from the control group: treatment group participants had significantly lower scores on the Beck Depression Inventory-II. These effects were greatest in the early stages of treatment (2-4 weeks) then flattened out toward the end of the study. Scores on the other two depression inventories were not significantly different between groups. There were no significant differences between groups on mental status assessments.
Only 3 out of 45 subjects reported negative side effects: one had a headache and two had mild electrical burns from treatment.
Takeaway: since all participants were being treated with an anti-depressant during the study, this may explain the lack of significant between-group differences on two depression inventories. This points to the possibility of a placebo effect or that tDCS as an add-on to medication does not improve outcomes. Given that the steepest declines in depression occurred in the first 2-4 weeks (completion of 10-20 sessions), this may indicate a ceiling for number of tDCS sessions needed to achieve results.
Citation: Oh, J., Jang, K. I., Jeon, S., & Chae, J. H. (2022). Effect of self-administered transcranial direct stimulation in patients with major depressive disorder: A randomized, single-blinded clinical trial. Clinical Psychopharmacology and Neuroscience, 20(1), 87-96. https://doi.org/10.9758/cpn.2022.20.1.87
In a follow-up study, Oh and colleagues conducted a single-arm (no control group) study of home-based tDCS treatment for depression. This study initially enrolled 61 participants 19-65 years old who had a diagnosis of unipolar major depressive disorder. Participants were not permitted to take anti-depressants during the study. TDCS was self-administered at home for 6 weeks, with a protocol of 1.5-2 m/A intensity to the DLPFC (anode), 5-7 sessions per week, 30-minutes per session, for a total of 30-42 treatment sessions at the end of the study. Depression scores and anxiety scores were assessed at 2-week intervals. Forty-three participants completed the full 6-week treatment. Depression scores were significantly lower at the end of the study compared to baseline, and significant decreases occurred at each 2-week interval. Surprisingly, depression remission rates were not related to the number of treatment sessions, although there were small numbers of participants in the lowest-compliance groups.
Takeaway: this study’s simple design ensured that the effects of tDCS home-based treatment for depression could be isolated without the potential confounding effect of anti-depressant medication. Without a control group, it is possible that the placebo effect occurred. However, with the similarity in results to other studies using a control group (see Oh et al., 2022), it is likely that the tDCS device caused beneficial improvements in brain functioning.
Citation: Oh, J., Jeon, S., Ha, T. H., Myung, W., Lee, S. H., Ko, Y. H., Kim, D. H., Lee, H. Y., & Chae, J. H. (2023). Effect of home-based self-administered transcranial direction stimulation in patients with mild to moderate major depressive disorder: A single-arm, multicentral trial. Clinical Psychopharmacology and Neuroscience, 21(2), 271-278. https://doi.org/10.9758/cpn.2023.21.2.271.
Do people suffering from epilepsy, depression, and anxiety experience improvement in their psychiatric functioning as a result of tDCS administered at home? The results of a 2021 study found the answer to this question to be YES: for both treatment and control groups! Twenty-six participants with epilepsy and depression were recruited for this randomized clinical trial. For the first 4 weeks of treatment, participants self-administered TDCS 5 times per week (once daily) using the F3/F4 montage at 2 m/A for 20 minutes. After the first 4 weeks, participants received three additional once-a-week sessions in a lab (for 23 total TDCS sessions). Twenty-two participants were taking psychiatric medications during the study. The blinding procedures were effective as only three participants believed they were in the placebo group (more on that later).
Participants were evaluated for various symptoms including depression and anxiety at day 1, 15, 30, 60, and one year after the study. Three dropped out of the study. There were no adverse effects on seizure rates from the tDCS treatments. Participants in both treatment and control groups experienced decreasing depression scores over the course of the study. For the placebo group, there was a slight uptick in depression scores at the 60-day and one-year follow-up. Ultimately, there were no significant differences for depression or anxiety between groups, pointing to the role of the placebo effect.
Takeaway: although the results point to the placebo effect (all but three participants thought they were receiving tDCS), not all participants in the treatment group received all 23 tDCS sessions. Perhaps additional sessions could have differentiated the group outcomes.
Citation: Mota, S. M., de Castro, L. A., Riedel, P. G., Torres, C. M., Bragatti, J. A., & Brondani, R. (2021). Home-based transcranial direct current stimulation for the treatment of symptoms of depression and anxiety in temporal lobe epilepsy: A randomized, double-blind, sham-controlled clinical trial. Frontiers in Integrative Neuroscience, 15, 1-12. https://doi.org/10.3389/fnint.2021.753995
A 2022 open-label (no control group) study of 26 participants assessed the effectiveness of home-based devices at treating depression in participants who were either taking antidepressants (12 subjects) or completing CBT psychotherapy (14 subjects). Thus, tDCS was the only change in treatment during the course of the study. All participants were clinically depressed at the study’s initiation based on current assessments. The course of treatment lasted for 6 weeks: 5 sessions of TDCS per week were administered for 3 weeks, followed by 2 sessions per week for 3 weeks (a total of 21 sessions). Treatments consisted of 30-minute sessions of 2 m/A of current in the F3/F4 montage: 23 participants used the Flow Neuroscience device, 3 used the Neuroelectrics Starstim 8 device. Sessions were monitored either in person or via video-call to ensure correct use of the device.
Twenty-four participants completed the 6-week treatment and 18 responded to the 6-month follow-up. Depression scores continued to drop across the 6-week treatment period, followed by very little variation in scores between 6-weeks, 3-months, and 6-months. At the end of the 6-week treatment, almost 92% had reduced symptoms of depression and almost 88% had achieved full remission. The treatment effects held even to the 6-week follow-up with 91% still showing reduced symptoms and almost 74% in full remission. “The high rates of remission were maintained at 6 months, reflecting the long-term effects of the treatment, and participants reported a noticeable impact in their lives” (p. 200).
Participants answered questions about usefulness and effectiveness of the home devices. Asked if they would recommend the use of TDCS to others, almost 90% said they would strongly or very strongly recommend the treatment at the 6-month follow-up and 83% said the treatment was very or quite helpful.
Takeaway: results showed that tDCS home-based application was effective as an add-on for either psychotherapy or anti-depressant medication. Since participants were already participating in these other treatment modalities, it allowed the research team to assess the improvement in depressive symptoms resulting from tDCS treatment (all participants were clinically depressed at baseline). However, in the absence of a control group, the placebo effect cannot be ruled out. Compared to other studies that had a high drop-out rate for home-based devices, this study experienced only a 7.7% dropout rate, most likely because each session was monitored in person or by video. Home-based devices that are easy to operate (correct placement of electrodes is essential to successful outcomes) and include in-person instruction and/or monitoring are likely to reduce unpleasant side effects.
Citation: Woodham, R. D., Rimmer, R. M., Young, A. H., & Fu, C. H. Y. (2022). Adjunctive home-based transcranial direct current stimulation treatment for major depression with real-time remote supervision: An open-label, single-arm feasibility study with long-term outcomes. Journal of Psychiatric Research, 153, 197-205. https://doi.org/10.1016/j.jpsychires.2022.07.026
In my next post, I will discuss ways to improve safety and efficacy using home-based tDCS devices.