Are there health risks associated with tDCS?
To date, no seizure or life-threatening conditions have been described with the use of tDCS. However, the first modern tDCS studies in major depression were carried out only in 2005, and, therefore, this method might have unknown side effects and/or risks.
What is a typical tDCS session?
Patients sit in a comfortable chair or lay down in a comfortable bed. At the beginning of each tDCS session, two water-soaked electrodes are applied to the patient’s scalp. Their location is determined according to a procedure 10-20 International System for Electroencephalography (EEG). Based on these measurements, the anode/positive electrode is placed on the left side of the front of the head (i.e.,“prefrontal cortex”), and the cathode/negative electrode is placed on the right side of the forehead (i.e., “supraorbital area”). Specially-designed rubber bands are used to fix these electrodes in their proper position. The stimulation intensity is 2 milliAmperes delivered constantly for 20 minutes. Patients are monitored continuously to ensure correct positioning and comfort level.
Should I stop taking my current medications before starting tDCS treatment?
No. Patients are supposed to continue taking the exact same meds that they were taking before tDCS treatment (i.e., no changes in the medication regimen while doing tDCS treatment).
What are the most common side effects associated with tDCS?
Less than 15% of patients experience mild and transient headache for less than an hour after the first tDCS sessions, but common analgesics usually relieve it.
During tDCS there are minimal or no scalp sensations with stimulation and subjects tend to get used to it after a few seconds. Less than 20% of patients describe a slight tingling and/or a short-lived sensation of mild burning with the onset of stimulation (underneath the electrodes). In a recent large study, none of the subjects requested tDCS to be terminated or needed any medical intervention during or after sessions.
Transient redness of the skin where the electrodes were applied is observed in 5% of patients, and it usually lasts less than 40 minutes.
A small number of patients complain of short-lived fatigue, difficulty concentrating, and/or nausea during and/or just after the stimulation period.
Finally, tDCS has not been shown to be associated with cognitive impairment, such as memory loss or inability to concentrate. On the contrary, the treatment might even enhance some aspects of cognitive functioning, such as working memory.
How does tDCS compare with rTMS and with electroconvulsive therapy (ECT) in terms of its efficacy and tolerability?
Unfortunately, there are no published studies to date comparing tDCS to either rTMS or ECT.
When is tDCS treatment offered at the Douglas Institute?
Currently, tDCS is offered from Mondays to Fridays (except on holidays), from 11:00 AM to noon.
How long is a tDCS treatment?
Patients typically receive 10 to 20 tDCS sessions over 2 to 4 weeks.
Unless there is reasonable justification, patients who miss more than 2 tDCS sessions in a row or 3 tDCS sessions in total will not be able to continue with tDCS treatment. Furthermore, patients must arrive on time to their tDCS session and no delays will be tolerated. This policy is strictly enforced and we encourage patients who are considering tDCS to make sure that they will be able to follow the intensive schedule involved.
Am I going to be assessed during tDCS treatment?
Yes. Keep in mind that tDCS is currently offered only in an experimental/research context. Thus, at baseline, Week 2, and possibly Week 4, you will meet with a psychiatrist/researcher and be asked questions that will help determine whether tDCS is being effective and safe for you. More specifically, you will answer:
- Self-report questionnaires: Inventory for depressive symptomatology, Beck Anxiety Scale, WHOQOL BREF for quality of life, and FISER-GRSEB for side effects
- Clinician-administered questionnaires: Hamilton Depression Rating Scale, and Hamilton Anxiety Scale.
What is transcranial direct current stimulation (tDCS)?
tDCS is a non-invasive and portable neuromodulation technique in which weak electric currents are applied to the brain via scalp electrodes. It has been recently shown to be effective and well-tolerated for treating major depression, appearing to benefit up to half of the patients who have received it.
Although Health Canada has approved the device, tDCS is still an experimental procedure.
What are the main advantages of tDCS?
tDCS is a non-invasive procedure that requires no anesthesia or sedation. Thus, during tDCS sessions, patients remain awake and alert, and afterwards can return almost immediately to their regular activities.
Furthermore, tDCS treatment is not usually associated with the systemic side effects typically seen with the use of medications (e.g., weight gain, dry mouth, gastrointestinal discomfort). For these reasons, tDCS could be particularly interesting for people who have not experienced significant relief from medications and/or standard rTMS or who have had difficulties tolerating their side effects. However, tDCS is not right and does not work for everyone.
How does tDCS works?
tDCS delivers weak direct electric currents of 1 to 2 milliAmperes to the brain via two water-soaked scalp electrodes. These electric currents are able to "stimulate" or "inhibit" specific brain regions, depending on the polarity of the electrode (positive or negative). More specifically, the anode/positive electrode usually produces neuronal "stimulation", whereas the cathode/negative electrode usually produces neuronal "inhibition".
