The Truth About Electrical Brain Stimulation

A blow to the scalp with two damp sponges and electrodes is a pastime. A procedure called transcranial direct current stimulation (tDCS) has been shown to help you learn math , improve your language skills, and even work harder for longer . But scientists are divided over whether tDCS can actually do what it claims.

Some scientists are enthusiastic about the technology and say it has significantly fewer side effects than psychotropic drugs. Numerous studies show that it can improve our ability to learn anything, and there seems to be evidence that mild shock to the brain can help treat certain mental disorders.

Clinical trials are currently testing tDCS for the treatment of a long list of disorders, including depression, pain, insomnia, Parkinson’s disease, schizophrenia, and drug addiction. A community of biohackers and self-experimenters has sprung up in garages and online forums tocreate your own devices , or you can order a kit and test the technology yourself.

But other researchers are more skeptical, doubting that tDCS is as safe and effective as proponents claim. Despite promising laboratory results, none of the medical benefits have been confirmed by the FDA, and recent studies have questioned the technology’s ability to alter brain activity at all. Critics have expressed concern about the small size of the studies and the effects of placebos , as well as the potential for side effects such as skin burns.

Jason Forte, a cognitive neuroscientist at the University of Melbourne, says he is particularly worried about the potential dangers of using tDCS at home. “If the device is used incorrectly, there is a risk of damage to the skin at the electrode insertion site. Poorly designed devices, used incorrectly, can disrupt heart function, although this has not been reported. “

Within academia, this debate is normal. A new drug or device appears every ten years or so, capturing researchers and imagining the public. Before it’s released, scientists are conducting hundreds of studies to find out if the method is safe, how best to use it, and what it might be most useful for.

However, due to the relative safety and ease of assembly, tDCS bypassed most of the normal testing process and moved from the lab to the living room. Private startups such as The Brain Stimulator , TransCranial Technologies, and Halo Neuroscience are now selling DIY tDCS devices to curious experimenters and desperate patients. The shift has alarmed some researchers and regulatory experts, while others say they see no harm in sharing technology.

How brain stimulation works

TDCS shocks the brain with a simple, direct electric current — usually 1 to 2 milliamperes — for 20 to 30 minutes a day. The stimulation is felt as a tingling sensation or a slight tingling sensation at the site of the electrode application. Neurons communicate through electrical and chemical signals. Scientists believe that the small amount of current that neurons receive from tDCS increases the likelihood that they will trigger an electrical impulse, causing the neurotransmitter to travel to the brain.

tDCS is just one of several types of mild electrical brain stimulation. Other options include transcranial alternating current stimulation (tACS) and cranial electrotherapy stimulation (CES). In tACS, the keyword is “interleaving”. Unlike tDCS, the current in tACS is constantly changing, fluctuating between positive and negative. Scientists believe that tACS does not work by altering individual neurons, but by altering the electrical frequency of the entire brain, which could optimize it for various conditions such as sleep or attention.

In a related technology, CES, the current is also pulsed. Fisher Wallace, the company that sells CES devices, claims the technology can increase neurochemical levels in the brain, including serotonin, but there is little evidence that this is true. Of the three, this is the only device approved by the FDA for the treatment of depression, anxiety, and insomnia. But it hit the market before the FDA required proof of the effectiveness of Class III medical devices, so it hasn’t undergone the same testing that such devices face today.

tDCS has received more attention from researchers than other types of brain stimulation, including ongoing clinical trials, and therefore more experimenters trying to mimic them.

Device requirements have not been thoroughly tested

Michael Oxley was inspired to create his first brain stimulator device after reading a New Scientist article on tDCS in 2012. The mechanical engineer hoped that gentle stimulation of his brain would boost his energy levels and improve concentration. Five years later, Oxley sold tens of thousands of tDCS headsets through his company foc.us , which claim to “increase alertness, improve concentration and improve learning ability” and even “help you run farther and faster.”

However, Oxley acknowledges that the foc.us devices have not undergone any formal external testing or clinical trials, and instead base their claims on experimentation with themselves and the broader scientific literature.

These cognitive and physical performance claims are cleared by the FDA because they do not contain any medical claims. But Anna Wexler, a biomedical ethicist at the University of Pennsylvania, says they may be regulated by the FTC.

“[The FTC] has taken action against a number of companies claiming cognitive enhancement, both in the supplement world and in the brain training world, so they have shown a willingness to get involved,” she says. “They did not take any action against tCDS, but in practice they basically could.”

Oxley stressed that he does not advertise his product for the treatment of any mental illness, not only out of fear of an FDA retaliation, but also because he considers it irresponsible. However, in reviews of foc.us devices, several customers report using the product to treat their depression. Wechsler’s research confirms this; in a forthcoming study, she shows that a third of home users use the technology to self-medicate for conditions such as depression.

Possible benefits of tDCS

Marom Bixon, professor of biomedical engineering at the City College of New York, says tDCS alone doesn’t do much. Its true value comes in combination with training. He recommends using this technology before or while learning a new activity, such as playing the piano.

The neurons that fire together connect together. By increasing the likelihood that a neuron will fire, tDCS helps the brain make new connections during learning – a process called plasticity. Thanks to this ability to influence learning, tDCS is positioned to have such a wide range of potential applications.

“When you apply DC stimulation, you can change the current plasticity. Not creating plasticity, but changing plasticity, which is already happening, ”says Bixon. “DC stimulation can increase this plasticity, which basically makes learning more effective.”

With this type of functional targeting, Bixon says it doesn’t really matter where the sponges and electrodes are placed, because tDCS will only affect neurons that undergo plasticity.

In contrast, in conditions such as anxiety and depression, researchers seek to increase activity in a specific area of ​​the brain, the dorsolateral prefrontal cortex, which is inactive in people with depression. Daily stimulation of this area with tDCS returns neuronal activity to normal levels, which is believed to help improve mood in people.

A large study published earlier this year found tDCS to be more effective than placebo in treating depression. These results mean that tDCS may indeed improve symptoms of depression, but research has also shown that it is not as effective as traditional medications like SSRIs.

What could go wrong

Areas just a few millimeters apart can serve a wide variety of functions. With tDCS, the sponges that are applied to the scalp span several centimeters, so it is difficult to ensure that you are stimulating the desired area. Some researchers have raised concerns about the off-target effects of tDCS, especially in the treatment of psychiatric disorders that require activation of a specific area. The brain is like real estate: it all depends on location, location, location. Off-targeting effects are especially important for DIY brain stimulants, which may not be experienced in neuroanatomy.

“You target large groups of neurons, which then influence their interactions with other neural populations and networks, so electrode placement is really critical,” says Tracy Wannorsdall, a neuropsychologist at Johns Hopkins University School of Medicine. “We know that very small changes in the mounting of the electrodes – where we place them in the brain – can have vastly different effects in terms of cognitive outcomes.”

Research has shown that increasing function in one area of ​​the brain can actually decrease performance in another area. Less dramatic, but perhaps more relevant, are reports of home users experiencing burns or skin damage at the electrode site.

Another problem is that the technique may not do anything at all. Many studies report no effect on either behavior or brain activity when using tDCS. Perhaps in the most unique test of technology, scientists have demonstrated that only 10 percent of the electrical current travels into the skull of a corpse and reaches its brain. These results indicate that tDCS has much less of an effect on the brain than the researchers originally hoped, and perhaps not enough to significantly affect neuronal behavior.

So, should you do this?

Want to try it yourself? Rather than investing a couple hundred dollars on his own device, neuropsychologist Wannorsdall recommends joining one of 700 tDCS clinical trials listed on Clinicaltrials.gov, involving both patients and healthy people. “I think it’s too early for people to experiment with themselves,” she says.

But Bixon, a biomedical engineer, thinks experimenting with yourself isn’t all bad. Five years ago, his “harsh reaction [as] a researcher in the academic ivory tower [was] this is my toy, don’t touch it.” But now his position has softened. “I really hesitate to tell someone who is really suffering or whose loved one is suffering whether or not to do something,” he says. “I’m not going to approve of him, but I’m not going to condemn them either. Obviously, many of us in the clinical and basic research communities believe these technologies can be effective. ”