Bullet Summary: tDCS for Depression

Updated Aug 2023
©Jennie Dilworth, Ph.D

HISTORY

Galen (circa 129-200 A.D.) is credited with experimentally applying torpedo fish (which produce an electric charge) to treat headache and epilepsy.
Modern application of tDCS for depression began in the early 21^st century.
First randomized controlled trial published in 2006.

DESIRABILITY

Non-invasive, safe treatment with few side-effects
Can be administered in a clinic or using a home-based device
Affordable due to new home-based devices that require no prescription
May be better tolerated than antidepressants for some people
Faster results and less expensive than psychotherapy
Mechanism of action: tDCS restores brain to normal activity by increasing cortical activity and neuroplasticity in the DLPFC. May affect serotonin and dopamine.

TREATMENT EFFECTIVENESS: CLINIC/DOCTOR SUPERVISED*

(Meta-analyses published after 2019)

Sham (placebo) control condition simulates tDCS session with short electrical burst at beginning and end to simulate electrical current. Can be blinded or double-blinded.
2020 meta-analysis of 23 studies found tDCS was superior to sham for reducing depression, with small to medium effect sizes. tDCS was more effective as a stand-alone than an add-on treatment to existing therapies. (Razza et al., 2022)
2021 review of 15 clinical trials of tDCS for major depressive disorder: about half of these studies showed a positive result for tDCS effectiveness compared to controls (sham or another therapy). Meta-analysis of 13 studies showed that anodal placement on the left DLPFC location was most effective at treating depression. (Fregni et al., 2021)
2022 meta-analysis of 17 studies of tDCS and TMS combined with psychotherapy found these non-invasive brain treatments were less effective alone compared to combining them with psychotherapy. (He et al., 2022)
2022 meta-analysis of 208 randomized controlled trials of tDCS and TMS for various mental disorders found tDCS was significantly better than sham at reducing depression, substance-use disorder and schizophrenia symptoms. (Hyde et al., 2022)
Effect sizes for symptom improvement are comparable to those for antidepressant treatment alone
Mixed findings for combining it with pharmacotherapy
Less effective in people with treatment-resistant depression
A maintenance phase post-treatment of twice weekly sessions reduces relapse
Women and older adults show greater responsiveness to tDCS
No serious side effects: common side effects include tingling, burning sensation at electrode site, headache, drowsiness
Contraindicated for people with epilepsy, migraines, seizures, metallic implants, scalp conditions

*Note: meta-analyses referenced here have different foci but may include some of the same studies.

TREATMENT EFFECTIVENESS: HOME-BASED DEVICES

As a safe, effective treatment for depression, more companies are manufacturing home-based devices. They are optimal for people who cannot receive daily treatment in a clinic and were particularly useful during the pandemic.
Research on home-based devices emphasizes that failure to comply with treatment protocols impacts outcomes.
The first study using home-based devices was published in 2018; no meta-analyses to date.
2021 RCT compared tDCS to sham for depressed patients with epilepsy. Twenty-six patients completed 4-week active then 3-week follow-up sessions. Subjects in both groups had depressive symptom reduction with no significant differences between groups. Improvements remained for up to 1 year for some patients (Mota et al., 2021).
2022 RCT compared tDCS with sham. All subjects took an anti-depressant during study. Treatment group had significantly lower depression scores compared to sham group on BDI-II (Oh et al, 2022).
2022 open-label (no control group) study provided home tDCS to 26 subjects for 21 sessions. All subjects were being treated with anti-depressants or psychotherapy prior to tDCS treatment. At the end of treatment, 92% had significant symptom reduction and 88% were in remission. High remission rates maintained at 6-month follow-up (Woodham et al., 2022).
2023 single-arm (no control group) study tested tDCS effects on depression in 61 subjects who received 30-42 tDCS sessions. Subjects did not take anti-depressants during study. Depression scores were significantly lower at end of study; depression scores dropped at each 2-week interval (Oh et al., 2023).
2023 RCT of home tDCS device recruited 16 subjects comparing tDCS to sham. Only 11 subjects completed the trial due drop-outs receiving burns from the device. No significant differences between treatment and sham groups, however, all reported reduction in depressive symptoms (Kumpf et al., 2023).

PROTOCOLS

Strength: 1-2 mA
Session Duration: 20-30 minutes
Research has not established the minimum number of sessions to get results
Treatment Length: 3 or more weeks recommended to see results for home-based devices
Dose-response effect: current x duration x # of sessions
Electrode Placement: montage varies based on desired result
Anodal (+) electrode has an excitatory effect; cathodal (-) electrode is inhibitory
Electrode size: typically 5×5 cm or 5×7 cm
For accurate placement of electrode, measure scalp and follow 10/20 EEG system
Montage for Depression: For right-handed people, to target left dorsolateral prefrontal cortex, typically F3 (anode) and F4 (cathode) placement based on 10/20 EEG system. Cathode can also be placed over right supraorbital area.
Electrodes should be placed at least 7-8 cm apart to prevent shunting across scalp
Sponges on electrodes are wetted with saline solution (0.9%) and sponge should be damp but not dripping. Sponges need to stay wet during treatment to ensure conductance.
When placing electrodes on scalp, part hair to get as much contact with skin as possible
Do not place electrodes on areas with cuts or damaged skin
Gradually ramping up to higher voltage may decrease skin discomfort
Do not use with benzodiazepines

Sources:

Aparicio, L. V. M., Rosa, V., Razza, L. M., Sampaio-Junior, B., Borione, L., Valiengo, L., Lotufo, P. A., Besenor, I. M., Fraguas, R., Moffa, A. H., Gattaz, W. F., & Brunoni, A. R. (2019). Transcranial direct current stimulation (tDCS) for preventing major depressive disorder relapse: Results of a 6-month follow up. Depression and Anxiety, 1-7. doi: 10.1002/da.22878

Brunoni, A., Nitsche, M., & Loo, C. (Eds). (2016). Transcranial direct current stimulation in neuropsychiatric disorders. Clinical principles and management. Springer.

Brunoni, A. R., Moffa, A. H., Fregni, F., Palm, U., Padberg, F., Blumberger, D. M., Daskalakis, Z. J., Bennabi, D., Haffen, E., Alonzo, A., & Loo, C. K. (2016). Transcranial direct current stimulation for acute major depressive episodes: Meta-analysis of individual patient data. The British Journal of Psychiatry, 208, 522-531.

DaSilva, A. F., Volz, M. S., Biksom, M., & Fregni, F. (2011). Electrode positioning and montage in transcranial direct current stimulation. Journal of Visualized Experiments, 51, e2744. doi:10.3791/2744

Fregni, F. et al. (2021). Evidence-based guidelines and secondary meta-analysis for the use of transcranial direct current stimulation in neurological and psychiatric disorders. International Journal of Neuropsychopharmacology, 24(4), 256-313. doi:10.1093/ijnp/pyaa051

He, J., Tang, Y., Lin, J., Faulkner, G., Tsang, H. W. H., & Chan, S. H. W. (2022). Non-invasive brain stimulation combined with psychosocial intervention for depression: A systematic review and meta-analysis. BMC Psychiatry, 22: 273, 1-13

Hyde, J., Carr, H., Kelley, N., Seneviraten, R., Reed, C., Parlatini, V., Garner, M., Solmi, M., Rossin, S., Cortese, S., & Brandt, V. (2022). Efficacy of neurostimulation across mental disorders: Systematic review and meta-analysis of 208 randomized controlled trials. Molecular Psychiatry, 27, 2709-2719.

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

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. doi: 10.3389/fnint.2021.753995

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.

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.

Palm, U., Hasan, A., Strube, W., & Padberg, F. (2016). TDCS for the treatment of depression: A comprehensive review. European Archives of Psychiatry and Clinical Neuroscience, 266, 681-694.

Razza, L. B., Palumbo, P., Moffa, A. H., Carvahlo, A. F., Solmi, M., Loo, C. K., & Brunon, A. R. (2020). A systematic review and meta-analysis on the effects of transcranial direct current stimulation in depressive episodes. Depression and Anxiety, 1-15, https://doi.org/10.1002/da.23004

Thair, H., Holloway, A. L., Newport, R., & Smith, A. D. (2017). Transcranial direct current stimulation (tDCS): A beginner’s guide for design and implementation. Frontiers in Neuroscience, 11, 1-13.

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