Transcranial direct current stimulation (tDCS) devices, which apply low-intensity direct current to the scalp, are becoming popular at-home tools used to improve mental clarity while combating symptoms associated with COVID-19, ADHD, and even Alzheimer's disease.

Research into tDCS has picked up steam in recent decades, leading many to want to take advantage of the purported health benefits. But tDCS is not without its risks. If your patients are interested in so-called “brain zapping,” it’s important to discuss with them both the potential benefits and risks.

 

A brief history of tDCS

 

The use of tDCS has a long history, with early studies dating back to the early 19th century.

However, the specific technique of tDCS, involving the application of low-intensity direct current to the scalp, gained prominence as a non-invasive brain stimulation method in recent decades. Its potential benefits were first identified in an influential 2000 paper that demonstrated the modulatory effects of tDCS on cortical excitability in humans, sparking further interest and research in the field.

Stagg CJ, Nitsche MA. Physiological Basis of Transcranial Direct Current Stimulation. The Neuroscientist. 2011;17(1):37-53.

Since then, tDCS has been the subject of numerous studies exploring its effects on various cognitive, motor, and neuropsychiatric conditions. Its potential as a research tool and therapeutic approach continues to be investigated and refined, with ongoing advancements in understanding the underlying mechanisms and optimizing stimulation protocols.

 

All of this “buzz” may be leading patients to purchase devices that can offer tDCS—or “brain zapping”—from the comfort of their own home.

 

A deeper dive into the mechanics of brain zapping

 

Transcranial direct current stimulation works by applying a low-intensity direct current to specific areas of the scalp, which modulates cortical excitability and activity in the brain, according to an article in Restorative Neurology and Neuroscience.

Nitsche MA, Paulus W. Transcranial direct current stimulation--update 2011. Restor Neurol Neurosci. 2011;29(6):463-92. doi: 10.3233/RNN-2011-0618. PMID: 22085959.

 

The process involves the application of a weak electrical current, typically ranging from 1 to 2 milliamperes (mA). This current flows between two or more electrodes placed on the scalp. The electrodes used in tDCS consist of an anode (positive electrode) and a cathode (negative electrode). The anode is usually positioned over the target region of the brain, while the cathode serves as the reference point.

This polarization influences the resting membrane potential of neurons, which is the electrical charge difference between the inside and outside of the neuron. Anodal stimulation increases the neuronal membrane potential, making the neurons more likely to fire, while cathodal stimulation decreases the membrane potential, making the neurons less likely to fire.

By modulating the resting membrane potential, according to the Restorative Neurology and Neuroscience authors, tDCS can affect the firing rates and excitability of neurons in the targeted brain region. This modulation leads to changes in neural activity and communication within the brain networks. 

 

The benefits of this method, as cited by the authors of an article published by JSTOR Daily, include improvements in mood, increased creativity, memory enhancement, and accelerated learning.

Perkowitz S. Can zapping your brain really make you smarter? JSTOR Daily. November 27, 2019.

These benefits are purportedly available to patients at home, upon purchase of any of various tDCS devices, available online for a couple hundred dollars or less.

 

The devices are compact, handheld machines featuring two electrical leads capped with sponges. When ready to use, users dip the sponges into a saline solution and apply them to the head.

These devices are being used in the hope of achieving a bit of a “boost.” For some patients, this provides them with relief from symptoms associated with depression, ADHD, long COVID, and other conditions, according to an article from Harvard Health Publishing.

Shmerling R. Can electrical brain stimulation boost attention, memory, and more? Harvard Health Publishing. March 3, 2023.

 

 

Know the risks

 

Most tDCS devices are not yet FDA approved to treat specific conditions. The FDA has cleared tDCS devices for the treatment of major depressive disorder in adult patients who have failed to respond to antidepressant medications. (Note: FDA clearance means that the device has demonstrated safety and effectiveness for a specific intended use, while approval generally refers to broader recognition of a treatment as safe and effective.)

The specific tDCS device approved for this indication is the Soterix Medical 1x1 tDCS System.

FDA Grants Soterix Medical IDE Approval for Home-based tDCS-LTE Trial for Depression. Soterix Medical. July 7, 2020.

 

The article in JSTOR Daily notes that tDCS devices sold for at-home use may produce unintended effects.

“One model tested in a university lab actually impaired memory,” the authors wrote. “Incorrect use and placement of the electrodes can also produce unreliable results. All this could diminish any good effects from tDCS.”

On the other hand, as the authors of an article in Frontiers in Neuroscience note: “There are no reported indications of any serious adverse effects with the use of 1–2 mA tDCS. However, mild temporary side effects may occur, such as headache, a cutaneous sensation at the stimulation sites, moderate fatigue, redness of the skin under the electrode pad, difficulty concentrating, acute mood changes and nausea.”

Thair H, Holloway AL, Newport R, et al. Transcranial direct current stimulation (tDCS): a beginner’s guide for design and implementation. Frontiers in Neuroscience. 2017;11.

 

 

Effects on different patient populations

 

In particular, the side effects that tDCS may induce in children are largely unclear.

According to a study published by Frontiers in Human Neuroscience, the “degree of excitability” that tDCS may create in the brains of children is difficult to predict.

Auvichayapat N, Auvichayapat P. Transcranial direct current stimulation in treatment of child neuropsychiatric disorders: ethical considerations. Frontiers in Human Neuroscience. 2022;16.

 

As a result, researchers can’t rule out the potential for this treatment to induce seizures in young patients—though they believe it to be unlikely among the majority.

All things considered, tDCS could be a tool that patients can use to enhance memory, boost mood, and fight symptoms of depression and other mental health conditions. Research, however, has yet to confirm the efficacy of at-home tDCS use. For now, you may keep patients informed about the potential benefits—and risks—associated with it.