Transcranial Direct Current Stimulation (tDCS): The Definitive Guide [2020]

If you want to learn about Transcranial Direct Current Stimulation (tDCS), why tDCS is so powerful and how to study this cutting edge technology, then this is the guide for you.

Important Note: having some basic understanding of neuromodulation can be helpful in tackling this topic.

Transcranial direct current stimulation is a non-invasive neurostimulation method used to deliver current to targeted areas of the brain via the scalp. Transcranial direct current stimulation is heavily related to Transcranial Alternating Current Stimulation (tACS) and Transcranial Magnetic Stimulation (TMS), but differs in that tDCS focuses on the use of stimulating the brain with direct current, instead of alternating current or magnetics.

A wide range of potential applications of tDCS are being explored that include the treatment of depression and diseases like schizophrenia, and the use of the technology for cognitive repair and enhancement.

Practices typically involve the use of “tDCS devices”, and this method of brain-hacking has seen over 4,000 different research papers published since a paper published by Nitsche and Paulus in 2000 that sparked the first contemporary interest in the area of noninvasive brain-stimulation.

What is Transcranial Direct Current Stimulation?

Transcranial direct current stimulation (tDCS) is a popular brain stimulation technique that uses constant, low-level direct current delivered via electrodes on the head. A current between 1 and 2 mA is typically applied, and tDCS works by facilitating the depolarization or hyperpolarization of neurons.

tDCS is related to, but distinct from, many other forms of neuromodulation that include Transcranial Alternating Current Stimulation (tACS), Transcranial Random Noise Stimulation (tRNS), Transcranial Magnetic Stimulation (TMS) and Transcutaneous Electrical Nerve Stimulation (tENS).

Use of electric current for medically-based reasons has been in practice since earlier than the 16th century. There are historical accounts of Roman and Greek physicians using the torpedo fish in order to deliver a naturally occurring electric current to patients in order to heal gout and relieve pain. Developments that led to our ability to create and store electric current allowed scientists from the 16th century onwards to begin experimenting with the ability to use electricity to heal.

In the year 2000, a research paper by Nitsche and Paulus called “Excitability changes induced in the human motor Cortex by which transcranial direct current stimulation” sparked an interest in the scientific community to look at new ways of stimulating the brain with electricity. Since then until now there has been a flurry of academic research within the field where over 4000 papers on tDCS have been published since then.

With growing exposure in the mainstream and the consistently dropping cost for the equipment involved in the process of tDCS, stimulating the brain with electrical current for the purposes of improving cognition moved out of the realm of academia and into the hands of hobbyist neuro-hackers around the time of 2010.

A wide range of new startups exploring the possibilities of using tDCS in the consumer market began to emerge and provide interested users with access to affordable, yet high-quality, equipment to use at home. Since then until now, many startups around the world are exploring the applications of tDCS that include South Korean company YBrain, BrainGate, Modius, NuCalm, and Sweden-based startup Flow Neuroscience.

Why is Transcranial Direct Current Stimulation so powerful?

tDCS improves learning and skill acquisition.

tDCS has been found to improve the abilities of users to learn new skills and tasks for a variety of different areas. These include improved number processing and numeric skills, improved motor skills learning and motor task execution, improved driving ability and improved general learning rate.

tDCS improves the ability to learn new languages.

Research shows that the use of tDCS not only improves the ability to learn new languages, but also for users with impaired language skills to regain some of the previous abilities they had prior to injury. Skills such as word retrieval and the detection of mismatches, as well as the detection of grammatical errors all showed improvements with the use of tDCS.

tDCS has shown to be an effective tool to alleviate the symptoms of depression.

In a range of studies, tDCS has been shown to markedly increase the mood of patients suffering from major depressive disorder. In one randomly controlled trial it was found that three weeks of anodal stimulation in patients with depressive symptoms resulted in significant improvements in mood, attention and working memory.

tDCS has been shown to be an effective tool to other fight against food cravings.

Studies have consistently found that stimulation of the prefrontal cortex using tDCS reduces the cravings for sugar and high carbohydrate foods. The technology has even been shown in research to reduce the food cravings of individuals with severe eating disorders such as binge eating disorder (BED).

Studies have demonstrated that using tDCS to stimulate the dorsolateral prefrontal cortex significantly improves working memory.

While this finding has been consistent throughout a range of studies, stimulating other areas of the brain did not have the same effect on working memory. These findings were significant considering the importance of working memory in a variety of cognitive tasks.

tDCS improves stroke recovery times.

The simulation of a variety of areas of the brain using tDCS has been found in research to have a dramatic effect on the reduction of recovery time for stroke victims period in one study, after daily tDCS sessions 5 times a week for 2 weeks, patience saw an increase in verbal comprehension that was significantly higher in comparison to the recovery of the skill set by the control group did not receive tDCS.

A study in the journal of cognitive enhancement by Anna Wexler was conducted in order to determine who uses tDCS and why. The study aimed to provide an examination of those who purchase tDCS consumer devices, how they learnt about tDCS, the way in which they used tDCS and what motivated them to do so.

The study conducted in 2016 analysed the data from a survey distributed by 7 different consumer-facing tDCS companies, and surveys were provided to customers that made purchases. The study found that the majority of respondents were men from North America who are wealthy, liberal, in their forties and highly educated. Respondents also generally prescribed to being early adopters of technological trends.

Almost 75% of those who took the survey reported to be using tDCS with the aim of enhancing their cognition, roughly 40% use tDCS for some form of treatment and one quarter reported to be using the technology for the restoration of lost cognitive abilities in relation to age.

Within the group that used to tDCS for treatment, a majority reported using the technology with the aim of combating depression. Interestingly, while those who used tDCS for treatment purposes generally found the technology to be effective, the opposite was true for those aiming for cognitive enhancement or restoration.

Medical Professionals

Historically, physicians have experimented with tDCS to treat a range of ailments. Nowadays illnesses that are both neurological and psychological are being treated with tDCS.

Neurologists at the Johns Hopkins Physical Medicine and Rehabilitation centre use tDCS and other forms of brain stimulation to treat a range of conditions, including traumatic brain injury (TBI) and stroke, and for dealing with symptoms related to a wide range of issues that include language disorders, movement disorders, chronic pain and various forms of cognition impairment.

The neuromodulation directory, Neuromodec.com, lists a number of different physicians across the US that use tDCS to treat patients. As the knowledgebase surrounding tDCS grows, we can expect to see wider numbers of medical professionals also adopting this technology.

Researchers

Once the electric battery was discovered in the 18th century, early researchers such as Welsh (1773), Galvani (1791) and Volta (1792) all recognised potential for treatment using electricity and its ability to create different psychological states in patients.

Consistently since the 18th century until today researchers have continued to use tDCS as a way to treat patients, and have also continued to explore new applications of the technology as their ability to understand its effects and the neurology of the brain has improved.

Today many universities and research institutes focus either fully or in-part on researching the effects of the electrical stimulation of the brain. These include the Clinical Research Center in Kanazawa University Hospital, the Burke Medical Research Institute in White Plains, New York, and the Centre for Addiction and Mental Health at Campbell Family Mental Health Research Institute in Toronto.

Areas of research surrounding neurostimulation include combating addictions, the effect it has on mood, combating pain, and the effects that tDCS has on the motor cortex and muscle function.

What are the tools of Transcranial Direct Current Stimulation?

tDCS Headsets

tDCS headsets are apparatus worn by users that allow for the positioning of electrodes in order to target specific parts of the brain with electric current. The quality of the design of the headset is critical to ensure that the electrodes remain in place and do not move during the process.

Typically tDCS headsets consist of a band across the top of head, however with more advanced setups, headsets can consist of apparatus that fully covers the skull and allows for targeting of multiple areas of the brain at once.

With the use of a tDCS headset, different areas of the brain may be targeted that correspond to various desired results and issues, such as combating insomnia, improved motor function and the improvement of sleep.

tDCS Devices

tDCS devices create low levels of electrical direct current, that are passed through the scalp and into targeted areas of the brain. These devices simply channel the power from batteries into wires that are connected 2 moitened sponge pads that are connected to the user’s head.

tDCS devices differ from devices used in practices such as Deep Brain Stimulation (DBS) in that tDCS devices are fully non-invasive and do not enter the skull, where DBS devices are essentially implants that are surgically placed within the brain.

tDCS Electrodes

In the process of tDCS, electrodes are used to conduct direct current to the scalp of the user. There are three different types of electrodes which can be selected for use in tDCS: these are either rubber carbon pads, sponge electrodes, or self-adhesive pads.

Self-adhesive electrodes are cheap and easy to use. While this is beneficial, the drawback of the use of self-adhesive electrodes is that they can’t be used on areas that have any hair. Self-adhesive electrodes are also not optimal for use in tDCS with higher current range than 1.5 mA.

Rubber carbon electrodes require a conductivity gel in order to be used effectively and are more expensive than self-adhesive electrodes. Other equipment such as either a headband or other mechanism to prevent movement is important when using rubber carbon electrodes in tDC.

Sponge electrodes of the highest quality electrodes available for use in tDCS, and this is reflected in their significantly higher price on the open market. Other considerations are required when using sponge electrodes, such as additional preparation measures compared to using other electrodes. Saline solution must be used to soak the sponges prior to usage in order to gain the highest levels of efficacy, and again, using a headband to prevent movement is the critical for optimal results.

How can you learn about Transcranial Direct Current Stimulation?

Universities and Colleges

Universities known for their neuroscience faculties:

• Harvard University
• Stanford University
• University College London (UCL)
• University of California, San Francisco
• Massachusetts Institute of Technology (MIT)
• Columbia University
• University of Oxford
• University of Pennsylvania
• Washington University in St. Louis
• Johns Hopkins University

Universities that conduct tDCS research:

• University of Michigan Depression Center, US
• Johns Hopkins Physical Medicine and Rehabilitation, US
• Université Libre De Bruxelles, Belgium
• Federal University of Rio Grande do Sul, Brazil
• University of Sheffield, UK
• Jagiellonian University Medical College Krakow, Poland

Other Sources

Informational Youtube videos:

• tDCS for cognitive enhancement, Dr. Vince Clark, Professor of Psychology and Neuroscience at the University of New Mexico (55 minutes)
• Electrode Positioning and Montage in Transcranial Direct Current Stimulation, Dr. Pedro Schestatsky

Guides for placement and usage:

• tDCS montage guides, charts 7 resources, Caputron
• tDCS Electrode Placement Montage Guide, TotaltDCS

What is the future of Transcranial Direct Current Stimulation?

Although modern tDCS began with a paper in the year 2000, the origins of this technology began much earlier than that. Through Roman and Greek history, the torpedo fish was studied by the scientists of the time, as observations were made as to the medicinal benefit of using the electric current created by this animal to heal ailments including gout and other painful illnesses.

The 16th century philosopher Dawud al-Antaki also use the torpedo fish to treat vertigo in his patients, and it was in 1660 the German scientist Otto Von Guericke first invented a hand cranked electrostatic generator which became the first controllable form of artificial electricity to be discovered.

Later inventors and scientists such as Anton de Haen and Benjamin Franklin also used electric generators and devices known as Leyden jars for their healing benefits.

However as we’ve moved into the 21st century, the real potential of targeted electrical stimulation of the brain is beginning to unfold. Significant advances in EEG technology and other areas of neural imaging over the past 20 years have allowed researchers and physicians to study and apply tDCS in ways that were previously unimaginable.

Because tDCS is relatively inexpensive in comparison to other treatments, completely non-invasive, and has been shown from many research studies to have limited (if any) side effects, tDCS has risen to become a prime candidate for replacing many pharmacological treatments in rehabilitation settings.

In particular, tDCS looks to have the potential to become a common treatment for preventative disorders such as strokes and depression, and in the correction of disorders relating to the diminishment of neuronal function such as Alzheimer’s disease.

What has also become a trend now over the past decade especially, is the exploration of the use of tDCS in non-medical areas such as gaming and the military, along with the enhancement of athletic performance in a range of different sports.

While the many new applications of tDCS have so far been seen to have mixed results in terms of performance improvements, the technology consistently shows to be able to affect the way in which electrical information is processed and used throughout the brain, and has demonstrated the clear potential for neuromodulation in the future of medicine and beyond.

Originally published at https://emerging.technology on July 19, 2019.