Do DIY devices work to stimulate the brain? (2023)

It began more than a decade ago, when engineers and hobbyists began to get excited about jury-rigged electrical technology designed to improve brain function. The movement continues to grow, and brain zappers are no longer just young workshop mechanics, but also older professionals who spend hundreds of dollars on high-quality portable systems. As scientists, physicians, and industry leaders study these intriguing but controversial mind-altering practices, one thing is clear: the idea of ​​applying an electrical current to the scalp to promote learning or to treat illness in the comfort of your own home is gaining traction. But it works?

Known as transcranial direct current stimulation (tDCS), this form of attempted brain hacking isn't as far-fetched as it might sound. The brain runs on electricity. Brain cells accumulate charges that drive chemical signals across synapses, the tiny spaces between neurons. When we learn something, the synapses involved are conditioned to fire more easily, and tDCS supposedly amplifies this process. The tiny electrical currents that tDCS uses, typically one to two milliamps, can't actually trigger the chemical impulse that crosses a synapse, but some researchers believe tDCS strengthens synaptic connections to make learning more efficient. Small laboratory studies suggest it may improve alertness and reaction times. "You get more bang for your buck" by combining tDCS with traditional exercise, says Marom Bikson, a professor of biomedical engineering at the City College of New York.

The birth of the non-invasive brain stimulation movement is widely credited to a 2000 publication by German neurophysiologists Michael Nitsche and Walter Paulus. In a small study of healthy 20-year-olds, scientists showed that they could make neurons more or less excitable by sending weak electrical currents through the brain's motor cortex. The effects lasted minutes after stimulation. Previously, tDCS had only been studied in animals.

A later 2003 study showed that such stimulation could enhance a cognitive skill psychologists call motor sequence learning: the process of training the brain in the precisely sequenced steps needed to interact with the world, such as by Listening or performing a word movement. Several labs at Harvard Medical School and the National Institutes of Health took note of these results and conducted research that indicated tDCS showed promise for stroke and chronic pain rehabilitation.

Back in 2006, Brett Wingeier began looking into this area. Wingeier, who trained in medical devices, was the chief biomedical engineer at NeuroPace, a Silicon Valley company that makes brain implants designed to help fight epilepsy. He had also been working on brain stimulators to relieve cluster headaches and movement symptoms that plague Parkinson's patients. "You may be incapacitated, but you turn on the stimulator and everything goes away. It's amazing," says Wingeier. However, he notes that such devices “are only relevant for patients with relatively serious illnesses. They are surgical implants.”

Wingeier dreamed of using neurotechnology to help more patients, and maybe even healthy people. He was excited to see new tDCS studies, but many "were done with yellow sponges, measuring tape, and headbands," he says. The time seemed right to consider incorporating product design principles into what he calls "a legitimate consumer product" that people can just take out of the box and use.

Further plans took shape as scientists developed the possible mechanisms for how tDCS works. In a series of electrophysiological experiments published in 2009, Bikson and some of his colleagues showed that a weak electric field can synchronize activity in a neural network. These findings inspired Wingeier and other researchers who worked to target tDCS to specific areas of the brain.

Since the 2000 study by Nitsche and Paulus, researchers have published more than 4,000 scientific articles on tDCS, a third of them in the last two years. In the medical field, some studies suggest that brain stimulation could help people with neuropathic pain, as well as depression, schizophrenia, and a variety of other psychiatric conditions. Currently, tDCS is still being tested for medical use in the US, although these devices are approved in Europe to treat pain and depression. More than 800 tDCS trials are listed in the clinicaltrials.gov database, which tracks ongoing drug therapy or medical device trials. In one small study, tDCS appeared to improve the mood effects of mindfulness meditation, and an ongoing clinical trial is investigating whether tDCS can help slow cognitive decline when combined with a computer-based exercise program in older adults.

Additionally, a growing number of studies are testing tDCS in healthy people and suggest that it may improve working memory, attention and decision-making, and stimulate creativity. A 2012 study funded by the US Department of Defense showed that tDCS can improve surveillance by allowing participants to spot bombs, snipers, and other threats in blurry images twice as fast. Since then, four other labs have shown that the technology could improve learning: "one of the few effects of tDCS that has been replicated across institutions," says Vincent Clark, a cognitive neuroscientist and first author of the 2012 paper. Clark directs the Center for clinical psychological neuroscience at the University of New Mexico.

The tsunami of academic literature on tDCS has unleashed a corresponding wave of media articles claiming that brain shocks can improve memory, boost math skills and "bring out the genius in you". An article in theJournal of Medical Ethicscalls tDCS “the Swiss army knife of human neuroscience”. As the potential of tDCS reached the general public, home users flocked to cyberspace. In 2011, tDCS users created a Reddit forum and started a blog the following year. Thousands of home users visit these sites to discuss scientific articles, post educational videos, and ask questions such as: B. where to place the electrodes and how long to stimulate. The Reddit forum has grown from 2,500 to around 11,000 subscribers over the past five years.

In 2013, the first consumer wearable tDCS device, a gaming headset, was released. Since then, more than a dozen companies have started selling tDCS products. Some offer $40 kits that include leads, electrodes, and headbands that the customer assembles at home. At the other end of the spectrum, Halo Neuroscience, the San Francisco-based company Wingeier co-founded in 2013, sells $500 helmets for elite athletes. The device stimulates the motor cortex and, when combined with exercise, promises "gains in strength, explosiveness, endurance, and dexterity." Caputron, which launched in 2014, also sells a line of medical-grade consumer brain stimulation devices. The company distributed more than 10,000 tDCS products in 2015 and more than 20,000 in 2016.

Most consumer tDCS devices are not marketed for clinical use, but for entertainment and cognitive enhancement. None of the consumer kits have officially passed the rigorous testing process that a drug or medical device must undergo in order to be approved by the Food and Drug Administration, and the buyer only has confirmation from the manufacturer that it is fit for its intended use. And the uses can be ambiguous. For example, when companies claim that their tDCS device "increases focus" or "boosts brain function," it's hard to tell whether those devices are under FDA control, says Anna Wexler, who is now a postdoctoral researcher at the University of Pennsylvania and which examines the ethical, legal, and social implications of neurotechnology. The agency defines a medical device as "an instrument designed ... to affect the structure or any function of the body," she says. "How a manufacturer markets the product dictates the regulatory path," adds Wexler, who examined some of these issues in a 2015 report.Journal of Medical EthicsPaper. The claims of improvement have raised suspicions among scientists and led to more controlled laboratory studies. In an experiment published in March 2016, a team from the Netherlands reported that commercial tDCS headphones actually made participants less accurate on an established test of working memory.

Despite the uncertainty about efficacy claims, there is continued interest in tDCS as a tool to optimize mental function. The devices are small and seem relatively safe. Reviewing the literature on human tDCS studies, Bikson and colleagues reported in the fall of 2016 that conventional use in more than 33,200 sessions as well as in 1,000 repeat-session subjects did not cause any serious side effects.

A major issue in evaluating how well the technology works is that the vast majority of research studies use brain stimulation for purposes other than home users of tDCS. Compare home use to the groundbreaking 2000 paper by Nitsche and colleagues that tested whether noninvasive brain stimulation could help people move again after a stroke. "We just wanted to know if we could change the performance of the engine," says Nitsche. "Our question wasn't, 'Does the stimulation protocol induce peak performance?'" Home users of tDCS, on the other hand, are not particularly interested in making new scientific discoveries, says Wexler. "They are interested in self-improvement."

This search for improvements could potentially lead to adverse consequences. In 2016, clinicians and scientists working on tDCS published aAnnals of NeurologyEditorial warning of possible adverse effects. For example, stimulating an area of ​​the brain can help someone learn new material but impairs the ability to process what is learned. Changes in brain activity may last longer than the user expects or extend beyond the regions beneath the electrodes. Furthermore, the effects of tDCS vary greatly between individuals and with small changes in the process. When it comes to electrode placement, "just a few centimeters can be enough to change the effect," says Clark. "How long you stimulate, how much current you inject, whether it's two milliamps or one milliamp or something in between, all of that matters." Genetics, age, and skull thickness also appear to affect response. The technical specifications for medical applications are not yet clearly outlined, let alone the parameters for cognitive enhancement.

At a conference in New York City in the summer of 2017 that Bikson helped organize, tDCS researchers and providers came together to discuss the potential of the technology and concerns surrounding it and other forms of neuromodulation. In 2018, the group released a report designed to help consumers make informed decisions about buying and using these devices. “Right now, consumers are a bit confused. They see a $20 device and they see a $700 device,” says Bikson. "They may not have enough information to understand why the $700 device represents greater value to them."

And it looks like tDCS is just the beginning. In addition to applying direct current to the scalp, brain hacking researchers and do-it-yourselfers are experimenting with other methods, including alternating current stimulation and random noise. These could one day complement more established non-invasive medical technologies like magnetic stimulation and ultrasound to affect brain function and behavior. Transcranial direct current stimulation, says Clark, "is just the tip of the iceberg."