Transcranial direct current stimulation or tDCS refers to the delivery of a constant, low current directly to an area of interest in the brain with the help of small electrodes for neurostimulation purposes.

Though the procedure was originally developed for helping people who have suffered injuries to the brain such as strokes, tests carried out on healthy individuals have provided some indications about its usefulness in improving cognitive performance of individuals depending on which part of the brain is being stimulated. It is believed that tDCS helps to enhance language as well as mathematical skills, attention span, memory, problem solving capability and coordination.

This has led to the availability of devices, including kits that can be assembled at home for less than $10, that are capable of providing tDCS. Designs for making tDCS machines are available online for free. Further, you can buy the components you need at hobbyist stores. For main stream consumers, companies that offer nicely designed as well as packaged stimulation machines priced at around $250 are available now. It may be difficult for you to believe the claims of the device makers, but there is some scientific evidence to support their usefulness.

How do tDCS machines work?

The transcranial direct current stimulation device sends a steady, low direct current to the area of interest in your brain through the small electrodes. Typically, the current applied for approximately 10 to 20 minutes is several hundred times smaller compared to that made use of in electroconvulsive therapy for providing seizure-inducing shocks. This current helps to induce an intracerebral current flow which works to either increase or decrease the neuronal excitability based on the type of stimulation used. It is the change in neuronal excitability that leads to the alteration of the brain function at the area of interest.

The theory behind the working of tDCS is that the weak direct current serves to alter the electrical potential of the nerve membranes present within the brain. On the basis of the direction in which the current is applied, it makes it either easy or difficult for the neurons in your brain to fire. You need to properly position the electrodes and send the right current in order to enjoy the beneficial effects. Manufacturers claim that the tDCS machines increase the plasticity of your brain and make the neurons fire faster.

The claims of the manufacturers are not totally unfounded because reports presented by some researchers show that tDCS helps to reduce pain, treat Parkinson’s disease and autism, ease depression, control cravings for drugs and alcohol, repair damage caused by stroke, recover faster from brain injuries, and improve memory, fluency and reasoning. Researchers have also observed that some effects persist for days and even months. This is because the increased neuron activity at the time of using the device modifies the functioning of the synapses to ensure longer lasting after effect.

However, the changes are dependent on several factors including whether anodal (positive) or cathodal (negative) current is used. While the positive current increases neuronal activity, negative current suppresses neuronal activity.

Are tDCS devices safe to use?

Online communities that are dedicated to tDCS contain a good number of success stories. Many people claim to have experienced cognitive enhancements. They also claim that it has given them an edge over others at work or games. Surprisingly, negative reports are rare. Of course, some people seem to have experienced headaches, confusion, nausea and sleeplessness after using tDCS. Reports of mild skin burns and temporary visual effects are fairly common, but there no reports of serious injuries, seizures, or deaths so far.

This, however, does not mean that there are no risks involved. Peter Reiner, co-founder of British Columbia University’s National Core for Neuroethics, says that incorrect electrode placement by DIY users might stimulate the wrong area in their brain or cause the polarity of current to be reversed. Polarity reversal could impair the very functions that they are striving to improve. Further, no one is clear as regards the interaction between tDCS and chemical stimulants/recreational drugs such as marijuana or pre-existing conditions such as epilepsy. Sometimes, wrong usage can even alter their brain’s functional organization. Many neuroscientists are also of the opinion that tDCS can affect long-term neural development if used by children and young adults.

Manufacturers of tDCS devices have been able to address some of these concerns. They have made it impossible for users to apply excess currents, use it for a longer time or place electrodes in an incorrect manner by designing different headsets for improving different functions such as concentration and reaction time in the case of videogaming, performance and motivation when exercising, etc. However, the fact is that even the slick products are not safer than the DIY products. This is because the consumer products are not evaluated by an official body for effectiveness and safety, unlike those that are used for clinical research and medical trials.

Further, a paper published recently by the University of Oxford’s Institute for Science and Ethics points out that tDCS devices manufactured for the consumer market are functionally and mechanically equivalent to those that are used for medical neurostimulation. Therefore, these devices should also be regulated. However, Dr. Reiner of the University of British Columbia regulatory control would drive the technology underground and the cost of consumer tDCS devices higher.

Finally it is difficult to prove the effectiveness of stimulation. The results of the 2013 study carried out by Roi Cohen Kadosh and Teresa Iuculano, Department of Experimental Psychology, University of Oxford, showed that the human brain is actually well balanced. An improvement in performance experienced in one cognitive realm because of stimulation caused the aptitude in another realm to decline. Further, a study published by Dr. Cohen Kadosh last year showed that variations in individual responses to tDCS overshadowed the general effects. A meta-analysis carried out by Jared Horvath, a neuroscientist from the University of Melbourne, Australia, showed that tDCS is effective only in providing electrical response of muscles to stimulus. However, the indication is that even response will eventually disappear when the techniques become more mature. Though studies conducted by Dr. Jamie Tyler, professor, Arizona State University, show opposite results, he agrees that one out of four people may not experience any benefit immediately.

All said and done, the relief from certain medical conditions (for which conventional therapies are neither effective nor affordable) that tDCS devices promise to provide might tempt consumers to try them out. People may experiment with tDCS devices to improve their cognitive performance, but their safety should be ensured through regulatory control.