All you need to know about transcranial Direct Current Stimulation (tDCS)
What is tDCS?
tDCS delivers a gentle electric current through two electrodes placed on the scalp. This is what a tDCS headset looks like:
A brief history of brain stimulation and tDCS
So far, we’ve learned that tDCS is a gentle form of brain stimulation that treats depression. But where does it come from? Is there research to support it? And does it actually work?
Ancient time: Electric fish could relieve pain
Greek and Roman physicians observed that electric currents could relieve headache and joint pain. They used electric discharges from the “torpedo fish”! (Largus, 1529)
1998-2000: tDCS was reappraised!
The interest in brain stimulation increased among researchers and tDCS was reappraised. Two important studies showed that tDCS could help activate the brain’s cortex. (Priori et. al, 1998; Nitsche & Paulus, 2000)
After that, several studies used tDCS to investigate different brain areas or as a treatment for psychiatric disorders
2006: Research proved the antidepressant effects of tDCS
An RCT* study by Fregni and colleagues showed that tDCS could have antidepressant effects. The group of patients that received tDCS treatment had a 58.5% mood improvement, measured with the Hamilton Depression Rating Scale (HDRS), whereas the placebo group had a 13.1% mood improvement. (Fregni et. al, 2006.)
2010-2012: tDCS proved to be as effective as other depression treatments
RCT* studies by Loo and colleagues, Palm and colleagues and Blumberger and colleagues examined the effects of tDCS for depression. The results were included in a meta-analysis** by Brunoni and colleagues in 2016, showing that tDCS was comparable to rTMS and antidepressant medication when treating depression in primary care. (Loo et. al, 2010; Palm et. al, 2012; Loo et. al, 2012; Blumberger et. al, 2012; Brunoni et al., 2016)
2012: Experts recommended tDCS as depression treatment
- Kalu and colleagues performed a meta-analysis** of earlier studies, suggesting that tDCS has antidepressant effects, at the same time noting that future studies should use larger patient samples for clearer results. (Kalu et. al, 2012)
- Brunoni and colleagues concluded that tDCS is a suitable treatment for depression and can be used in clinical practice because the technique is noninvasive, has a low rate of side effects, is low-cost and portable.
“tDCS is a technique with a low rate of reported side effects, relatively easy to apply and less expensive than other neuromodulatory techniques — appealing characteristics for clinical use. In the past years, 4 of 6 phase II clinical trials and one recent meta-analysis have shown positive results in ameliorating depression symptoms.”
2013: Researchers found tDCS and medication to be a powerful combination
Brunoni and colleagues conducted an RCT* study. The researchers discovered that combining tDCS and antidepressant medication made both treatments more effective. The main scores on the Montgomery-Asberg Depression Rating Scale (MADRS) differed significantly between the group of participants that received medication and tDCS in combination and the group that received medication only (mean difference: 8.5 points). The scores also differed significantly between the combined treatment group and the group that received tDCS only (mean difference: 5.9 points) and between the combined treatment group and the placebo group (mean difference: 11.5 points). (Brunoni et. al, 2013)
2016: Researchers proved that tDCS is 100% safe to use
- Brunoni and colleagues performed a meta-analysis**, showing that tDCS was comparable to rTMS and antidepressant medication when treating depression in primary care. (Brunoni et. al, 2016)
- Through a meta-analysis**, Bikson and colleagues found that tDCS is safe to use and has never been associated with brain damage.
“To date, the use of conventional tDCS protocols in human trials (≤40 min, ≤4 milliamperes, ≤7.2 Coulombs) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions and 1000 subjects with repeated sessions. This includes a wide variety of subjects, including persons from potentially vulnerable populations.”
2017: Again, tDCS proved to be much more effective than placebo
Brunoni and colleagues found that 41% of depressed people noticed that at least half of their symptoms disappeared within 6 weeks of using tDCS. Only 22% in the placebo group experienced similar results. (Brunoni et. al, 2017)
2018: Researchers found the most effective ways to use tDCS
- Nikolin and colleagues performed a meta-analysis** showing that tDCS is safe to use and that injuries do not increase with higher levels of tDCS exposure. (Nikolin et. al, 2018)
- Pavlova and colleagues found that a combination of tDCS and antidepressant medication is an effective treatment for mild to moderate depression. Also, a treatment with 30-minute stimulation sessions is more effective than one with 20-minute sessions. (Pavlova et. al, 2018)
- Loo and colleagues conducted an RCT* study and found no difference between depressed participants given active tDCS treatment (2,5 mA) and those given sham tDCS (0.034 mA and two 60-second current ramp ups to 1 and 0.5 mA). According to the researchers, one possible explanation for the finding was that the weak current in the sham group affected participants’ moods. (Loo et. al, 2018)
2019: tDCS was found to be as effective, but less expensive than other treatments
- Mutz and colleagues compared different types of brain stimulation techniques to find out if they should be used as treatments for depression. The researchers found tDCS to be efficacious and a less expensive treatment than TMS, ECT or psychotherapy.
“…we found tDCS to be efficacious across outcomes in both pairwise and network meta-analyses. Given that tDCS tends to be a less expensive treatment than transcranial magnetic stimulation, ECT, or psychotherapy, this finding is particularly relevant for policy makers who might consider tDCS as a clinical therapy outside the research setting.”
- Flow Neuroscience introduces the first medically approved tDCS device for home use.
*An RCT (Randomised Controlled Trial) study is a type of research method used to make sure that results are as reliable as possible.
**A meta-analysis is a research method that combines results from multiple studies. This means that the results from a meta-analysis are particularly reliable.
Modern brain stimulation techniques
What is transcranial direct current stimulation (tDCS) and how is it different from other forms of brain stimulation? Hopefully, these questions can help clear things up.
What do tDCS, TMS and ECT look like?
What is tDCS, TMS and ECT?
tDCS: Transcranial direct current stimulation (tDCS) is a non-invasive, non-pharmacological and painless form of brain stimulation.
What drives the stimulation?
tDCS: Electric current.
TMS: Electromagnetic induction.
ECT: Electric current.
Where is tDCS, TMS and ECT used?
tDCS: tDCS is approved for treating depression and chronic pain in the EU, including the UK. It’s available for home use. Flow Neuroscience offers the first medically approved device for at-home depression treatment.
TMS: In 2009, TMS was approved by the US Food and Drug Administration (FDA) for depression treatment. Today, TMS is used in hospitals in the UK, the USA and Sweden.
ECT: ECT is used both in the EU and the USA to treat the most severe cases of depression. The technique is very different from tDCS and can only be used in hospitals under general anesthesia.
How do the techniques work?
tDCS: tDCS delivers a weak direct current (0,5-2 mA) to specific brain areas via electrodes placed on the scalp. It helps the cortex of the brain become more easily excited. tDCS can be used at home or at health care clinics.
TMS: Instead of direct electric current, TMS uses electromagnetic fields to alter the activity in specific areas of the brain’s cortex. TMS is administered by healthcare professionals and doesn’t require anesthesia.
ECT: An electric current passes through the brain to induce a generalised seizure in anesthetized patients. The current used in ECT is 400 times stronger than with tDCS and should only be used to treat the most severe cases of depression.
What brain area is stimulated?
tDCS: In the treatment of depression, the electrodes are placed to target the DLPFC (dorsolateral prefrontal cortex) of the brain.
TMS: TMS targets basically the same brain area as tDCS in depression treatment, that is the DLPFC (dorsolateral prefrontal cortex).
ECT: In the treatment of depression, electrodes are most commonly placed over the temporal cortex of the brain on both sides of the scalp.
What are the side effects from tDCS, TMS and ECT?
tDCS: Side effects are less severe than those from medication, TMS and ECT.
Side effects include mild stinging sensations under the electrodes and mild headaches that pass after 30 minutes.
TMS: Side effects are less severe than those from medication or ECT. Side effects include headaches and a small risk of seizures.
ECT: Side effects include confusion, memory loss and physical pain.
Is it available for home use?
Why should I trust Flow Neuroscience?
You don’t have to. Flow has been examined by external experts selected by the British Standards Institution (BSI). The Flow headset is CE-marked and medically approved for use in the EU. To get this approval, the manufacturer must prove that the device is clinically equivalent. This means that external experts on brain stimulation and health technology examined the headset and made sure it’s doing the same thing as the devices in the research studies. The CE certification ensures that Flow is based on scientific evidence, that the treatment reduces depressive symptoms and that the headset is safe to use.