TMS VS tDCS

Fisher Wallace Is NOT TMS Therapy

If you are comparing TMS therapy to Fisher Wallace’s at-home brain stimulation device, then this article will help you learn the differences. Both TMS therapy and Fisher Wallace Stimulator’s end goal is to stimulate the brain and cause neuromodulation. The similarities end there. Fisher Wallace Stimulator is NOT a TMS device. Instead, it is a tACS device. There are tens of other at-home brain stimulation that are either tACS or tDCS devices. You just didn’t hear of them because they don’t make the misleading notion of being a TMS therapy device at home. 

For the last few years, I notice an apparent confusion among patients looking into brain stimulation therapy for depression and anxiety about the difference between rTMS and CES (tACS and tDCS) devices. Though CES (tACS and tDCS) could have significant medical use. Fisher Wallace as a leader and all other CES (tACS and tDCS) devices are not TMS therapy. They shouldn’t be marketed as “at home TMS device”. Below I will explain some of the differences between the two.

How does tDCS work?

Transcranial direct current stimulation (tDCS) involves a low amplitude electrical direct current applied through electrodes on the scalp, targeting superficial areas of the brain. Although tDCS does not trigger action potentials, it modulates cortical excitability by shifting the neural membrane resting potential. Anodal stimulation is hypothesized to cause depolarization and increase neural excitability, whereas cathodal stimulation would cause hyperpolarization and decrease cortical excitability. Some devices use direct current and called tDCS, while others use alternate current and called tACS. Both tDCS and tACS are under the classification of Cranial Electrotherapy Stimulator or CES for short by the FDA classification.

How does TMS work? Click here to learn more

Early studies used 20-min sessions of 1 mA anodal stimulation over the left DLPFC, the cathode being placed over the right supraorbital region. More recent trials support the use of longer sessions (30 min) of tDCS delivered at a higher intensity (2 mA) with the cathode placed over the right DLPFC.

The antidepressant effect of anodal tDCS of the left DLPFC was first described in 2006. Since then, more than 10 sham-controlled RCTs were published in this context, and various open-labeled studies and case reports. 

Since 2011, the antidepressant efficacy of tDCS was appraised in various meta-analyses, with the response and remission rates as primary and second outcome measures, including the calculation of effect sizes. In these works, an antidepressant response was usually defined as a 50% reduction in post-treatment scores on the Hamilton Depression Rating Scale (HDRS) or the Montgomery–Asberg Depression Rating Scale (MADRS). In the first meta-analyses, active tDCS showed no or only modest superiority compared to the sham condition. More recent meta-analyses (Shiozawa et al., 2014; Meron et al., 2015) and an analysis of individual patient data (Brunoni et al., 2016a), including the sizeable SELECT-TDCS trial conducted by Brunoni et al. (2013b), suggest the superiority of active tDCS compared to sham treatment. 

In the SELECT-TDCS trial, the combination of tDCS with sertraline hydrochloride (50 mg/day) was superior to each treatment considered solely or to placebo, suggesting an additive interaction of tDCS and antidepressant pharmacotherapy. The effect of tDCS may be mediated by pharmacological modulation of serotonergic and noradrenergic neurons located in deep brain structures, although they are not directly affected by the superficial current flow generated by tDCS (Brunoni et al., 2014b).

Click here to learn more about TMS for depression

The European Chapter of the International Federation of Clinical Neurophysiology commissioned a group of experts to investigate the therapeutic use of transcranial direct current stimulation (tDCS). The group explored the use of tDCS for pain, Parkinson's disease, movement disorders, motor stroke, post-stroke aphasia, multiple sclerosis, epilepsy, consciousness disorders, Alzheimer's disease, tinnitus, depression, schizophrenia, and craving/addiction. 

The group concluded the following: Current evidence does not allow making any recommendation of Level A (definite efficacy) for any indication of tDCS. 

Level B recommendation (probable efficacy) is proposed for:

• Major depressive episode without drug resistance: Anodal tDCS of the left dorsolateral prefrontal cortex (DLPFC) (with right orbitofrontal cathode) in major depressive episode without drug resistance.

• Fibromyalgia: Anodal tDCS of the left primary motor cortex (M1) (with right orbitofrontal cathode) in fibromyalgia.

• Addiction/craving: Anodal tDCS of the right DLPFC (with left DLPFC cathode) in addiction/craving.

The bottom line, tDCS is probably helpful in depression that is not treatment-resistant (no previous failure of medications). tDCS is probably NOT helpful in treatment-resistant depression or TRD (depression that didn’t respond to psychotherapy and antidepressant medications)

That is the main difference between rTMS and tDCS. rTMS is backed up by a huge amount of clinical evidence supporting its efficacy and safety in treating Treatment Resistant Depression. On the other hand, tDCS lacks clinical evidence to support its efficacy for Treatment Resistant Depression.