October 21, 2024

expert reaction to study looking at a home-based transcranial direct current stimulation treatment (tDCS) and major depressive disorder

A study published in Nature Medicine looks at home-based brain stimulation as a possible treatment for major depressive disorder. 

Dr Julian Mutz, King’s Prize Research Fellow, King’s College London, said:

“Depression is a common mental health condition that carries a significant disease burden.  While medication and psychotherapy are effective, they do not work for every patient and sometimes cause unwanted side effects.  Non-invasive brain stimulation techniques, such as transcranial magnetic or electrical stimulation, offer alternative treatment options.  A barrier to more widespread use is the need for frequent visits to the clinic, usually five times a week for several weeks.  There is considerable interest in transcranial direct current stimulation (tDCS) due to its potential for home-based use.  However, data from randomised clinical trials are limited.  Prior studies have supported its feasibility but more data are needed to establish efficacy, an important gap that this study addresses.  In this phase II trial of 174 patients, the authors show that tDCS was efficacious over a ten-week period, a longer duration than prior home-based trials.  Nearly half of the patients receiving tDCS achieved clinical remission, compared to just over 20% in the control group.  The treatment also showed a good safety profile, which will provide reassurance to both clinicians and patients.  Given that two of the largest randomised controlled trials of tDCS yielded negative results, this trial will undoubtedly contribute to the ongoing discussions about tDCS as a treatment option for depression.

“This is a well-designed trial of tDCS, with sample sizes comparable to those of the largest tDCS trials in the clinic.  The trial had appropriate procedures in place to mitigate potential risks of bias and the authors carefully monitored and reported on adverse events and safety.  The assessment of efficacy was not limited to clinician ratings but also included patient reported outcomes.

“tDCS is different from electroconvulsive therapy (ECT).  ECT involves inducing a seizure and is applied under general anaesthesia.  ECT is generally reserved for the most difficult-to-treat patients when other treatment approaches have been unsuccessful.  tDCS applies mild electrical stimulation to the scalp while the patient is fully awake.”

Prof Jonathan Roiser, Professor of Neuroscience & Mental Health, UCL, said:

“This paper reports on a moderately large clinical trial of transcranial direct current stimulation (tDCS) for depression.  tDCS is a non-invasive brain stimulation method that has been tested in many previous depression trials – with mixed success – and involves delivering a mild electric current to a specific brain region (often, as in this study, to the prefrontal cortex, with electrodes placed on the forehead).  tDCS was delivered several times per week for 10 weeks, for half an hour each time.  In the “sham” (i.e. placebo) group, patients received only very brief stimulation to mimic the sensation of the active tDCS on the skin, in an attempt to introduce blinding.  What was relatively new in this study was the use of a commercially available device patients could use at home by themselves, with remote support from the study team.  Patients were told to use the machine five times each week for the first three weeks, reduced to three times each week for the remaining seven weeks.  Around two-thirds of the patients were taking antidepressant medication.  Some of the study investigators had a financial interest in the company that makes the tDCS device.

“On average, both groups had quite substantial reductions in depressive symptoms (rated by the research team using a standard clinical interview) over 10 weeks.  However, there was a greater reduction in the active stimulation group, around half of whom got completely better.  This improvement was statistically better than in the sham group, around one-quarter of whom got completely better.  The size of the difference was in the small-to-moderate range, which is quite similar to trials of antidepressant medication.  The major challenge in interpreting this otherwise promising finding relates to problems with blinding: around three-quarters of the active stimulation group correctly guessed their treatment allocation, while less than half did so in the sham stimulation group.  This was probably due to minor side effects caused by the stimulation device; mostly skin redness, which occurred in nearly two-thirds of those receiving active stimulation, but also skin irritation and cognitive problems (trouble concentrating) in a small number of patients.  If there was clear skin redness on the forehead, it is possible that the researchers conducting the clinical interviews might also have also guessed the treatment allocation.  It is worth noting that a couple of the patients had more serious side effects, specifically skin burns which may have been caused by incorrect use of the device.”

‘Home-based transcranial direct current stimulation treatment for major depressive disorder: a fully remote phase 2 randomized sham-controlled trial’ by Rachel D. Woodham et al. was published in Nature Medicine at 16:00 UK time on Monday 21 October 2024.

DOI: 10.1038/s41591-024-03305-y

Declared interests

Dr Julian Mutz: “I do not have any COIs to report.  I have co-authored publications with the senior author in the past, but have not been involved in any collaboration recently.”

Prof Jonathan Roiser: “No interests to declare.”