Response to The Electric Brain

Transcranial direct current stimulation (tDCS) is a technique for stimulating the brain in the hopes of achieving therapeutic benefits and/or intelligence enhancement. At home do-it-yourself (DIY) tDCS is growing in popularity and online forums such as we reddit.com and youtube.com are posting instructional content for tDCS users. Alarmed by this behavior, in The Electric Brain, Colton Smith sought to generate a dialogue around the potential risks of such activity and the role the neuroscience community should be playing with DIY tDCS users. He suggests that tDCS, especially when employed in a DIY fashion, may be invasive, unsafe, could unintentionally stimulate unintended areas of the brain, could impair development of the brain, or lead to some form of addiction. Smith argues that members of the neuroscience community should have a duty to inform the public about potential risks of tDCS. Because compulsory obligations imposed on professionals are typically in the form of regulation, including certifying boards and statutory standards of conduct, we respond here with some concepts about if, and how, DIY tDCS fits into existing regulatory frameworks. We believe that because Smith’s safety concerns are extreme, regulators should not regulate DIY use of tDCS at this time. Rather, we suggest that more robust research is warranted and that any decision to proceed toward regulation should be based on solid scientific evidence.

Before we discuss whether and how tDCS might be regulated (should the evidence suggest that such government intervention is necessary), it is important to understand Smith’s underlying concerns about safety and why they might or might not warrant regulation. At the core of Smith’s argument are two theses: (1) tDCS may not safe; and that as a consequence of such risks (2) neuroscientists should have a duty to inform DIY users of said potential risks. We disagree. We pose that the evidence does not currently support a need for alarm about tDCS safety. We also believe that neuroscientists educating users on the potential risks would likely be ineffective and superfluous.

A. Safety risks and research

The existing research on tDCS has been inconsistent but recently most researchers assessing the effect of tDCS note only minor safety concerns including transient adverse effects such as skin sensitivity, generic discomfort, and headache, if anything.

In 2011, researchers reported a lack of conclusive information on tDCS effects. Led by psychiatrist Andre Brunoni, of the Department of Neurosciences and behavior, Institute of Psychology, University of Sao Paulo, a team of researchers concluded that the existing body of research lacked evidence on adverse effects of tDCS, not that these effects did not exist (Brunoni et al. 2011). Through a meta-analysis of 172 tDCS studies, the researchers found that previous studies had not been designed to appropriately and systematically assess the adverse effects of tDCS (Brunoni et al. 2011). They recommend ‘that future clinical research explores [adverse effects] in an active, systematic fashion, in order to guarantee that tDCS is a safe and sham-controllable technique’ (Brunoni et al. 2011, 1143).

Since Brunoni published, researchers have designed studies to catalog the adverse effects of tDCS with mixed results. For example, journalist David Noonan recently reported on tDCS’ potential to benefit people with brain injuries and generally improve concentration (2016). In an ongoing study conducted in collaboration with Air Force Research Laboratory, 1000 healthy volunteers between ages 18 and 44 receive 30 minutes of tDCS. ‘Researchers say they haven’t seen significant side effects, just some skin sensitivities from the electrodes. Some subjects who receive tDCS report headaches afterward, but so do some of those who received sham treatments’ (Noonan 2016). Although Aron Barbey, Director, Decision Neuroscience Laboratory, Beckman Institute, University of Illinois, the primary researcher featured in the article, is ‘put off by the suggestion that it’s possible to become smarter by just flipping a switch,’ he raises no concerns for harm to users of commercially available tDCS devices (Noonan 2016).

Also, similar to Brunoni, in 2016 Marom Bikson, of the Department of Biomedical Engineering at The City College of New York, et al. (2016) also conclude a lack of evidence of harms in a study on the evidence of supervised tDCS use safety.

To date, based on over a total 33,000 sessions and over 1000 subjects who received repeated tDCS sessions, there is no evidence for irreversible injury produced by conventional tDCS protocols within a wide range of stimulation parameters … . This analysis consolidates and adds to existing evidence on tDCS safety and facilitates further research of tDCS in human subjects. (Bikson et al. 2016, 657)

Neuroscientists Laura Steenbergen, an associate professor in the Cognitive Psychology Unit at Leiden University, and her colleagues had entirely different findings and recently reported that a tDCS device sold commercially impaired cognitive performance (Steenbergen et al. 2016). In a study of 24 healthy young volunteers, test subjects reported burning sensation at the electrode location, generic discomfort, and headache at statistically higher rates than sham subjects. The authors concluded that

even if the consequences of long-term or frequent use of the device are yet to be demonstrated, our findings provide strong support for the claim that the scientific community should play a more critical and active role in validating and testing far-reaching claims made by the brain training industry. (Steenbergen et al. 2016, 641–642)

The variation among the different studies demonstrates the lack of consistency (in method and findings) and long-term effect research on tDCS. Perhaps Smith is correct and there are potential serious health complications that are unknown to the neuroscience community at this time. However, so far the research points only to either relatively benign usage or only transient side effects such as itching or slight burning sensation. The user could quickly notice and respond to issues that occur at time of tDCS use by simply ceasing use. Furthermore, none of the reported studies thus far have demonstrated serious injury, death, or other major long-term consequences. For this reason, we argue that at this time the need for alarm is minimal.

B. Public perception of risks

Even if tDCS does have as-yet unarticulated potential dangers, requiring neuroscientists to educate the masses about potential risks may be ineffective and superfluous. One of Smith’s bases for arguing neuroscientists need to inform the public about the tDCS risks is that DIY users may be unaware of the health and safety risks he discusses. However, in 2016 in an open letter concerning DIY tDCS users, 39 people and organizations in the neuroscience community, led by Rachel Wurzman in the Department of Neurology at the University of Pennsylvania, told readers that the research on tDCS is incomplete and listed potential dangers to DIY users (Wurzman et al. 2016). It is not clear that this letter, published in Annals of Neurology, reached a wide audience. However, an online search engine search on 22 June 2017 for ‘warning tDCS’ returned this letter as the first non-sponsored result.

In publishing and distributing these cautions that can be tapped using a straightforward Internet search, members of the neuroscience community have already done what Smith proposes. We believe that continuing to repeat this will be unsuccessful without proposals on how to reach new audiences, methods to improve reception of the information, or more substantial and concrete research conclusions.

Additionally, many people using tDCS likely already understand and accept some degree of risk. Even for those who have not read the neuroscientists open letter, the tDCS subreddit page for tDCS (address: https://www.reddit.com/r/tDCS/) explicitly presents the following disclaimer:

Disclaimers

1. Using a tDCS device safely requires (at minimum) a basic understanding of how electric current interacts with the body. If you don’t understand why you can be killed by a 9 V battery, you probably shouldn’t be tDCSing yourself.

2. tDCS (and related technologies) are experimental. In most cases, there are options available for treating medical and psychiatric problems which have more demonstrated efficacy and safety than tDCS. If you are concerned about some aspect of your mental or physical health, please consult a medical professional before using tDCS.

Nothing posted here should be considered valid medical advice, everything is discussed in a strictly scientific context, if you choose to use a tDCS machine, it is your responsibility to ensure that it works correctly and your usage is within reasonable limits.

Warnings like this demonstrate that, at the very least, some members of the tDCS community are more informed about tDCS’s potential risks than Smith gives them credit for. The reddit users who wrote or read the disclaimer have been made aware – at least in theory – that the safety and efficacy of DIY tDCS are not guaranteed.

However, one can argue that it is likely many of the reddit users skipped over the disclaimer as useless legal jargon akin to terms and conditions accepted on a website. And it is equally likely that many of those who read the disclaimer did not thoughtfully contemplate each of the hypothetical hazards and internalize the impact they may have. The disclaimer certainly does not provide robust detail about electricity risks nor does it explain demonstrated or hypothesized side effects of tDCS. Further, Smith hypothesizes some side effects of tDCS – such as addiction – that the average person might not anticipate as a potential hazard.

On the other hand, people who ignore disclaimers may be the same people who would equally ignore neuroscientists trying to persuade them with data. Smith’s recommendations about neuroscientists educating the populace may be no more effective than the reddit disclaimer. More to the point, most people have been raised around electricity. Anyone who has felt a jolt pulling a cord out from a socket or been burned by a hot light bulb has a rudimentary understanding that electricity has the potential to be dangerous – even if they do not understand the exact mechanisms or degrees of injury. The people placing electric probes on their scalp bring with them experiences from living around electricity and are likely choosing to use tDCS in acceptance of some risks, rather than in complete ignorance of them.

C. Innovation vs. safety

Even if we accepted Smith’s concerns about tDCS and the need to inform the public, to have any force his proposals would need to be implemented in the form of regulation. Regulation comes with its own challenges as evidenced by the ongoing policy debate around innovation policy and safety. In many instances, the public hopes for new advancements to rush to market, but also demands safe, effective products. Ludlow, Bowman, and Kirk (2009) (Ludlow, an Associate Professor of Law Resources at Monash University) argue, using nanotechnology as their case study, that new technology will go through periods of over and under regulation and that finding the appropriate balance is a challenge. Under-regulation may yield human, environmental, and health implications while over-regulation can serve as a barrier to innovation, technical progress, and industry competitiveness (Ludlow, Bowman, and Kirk 2009). The authors also note that it is difficult to accurately identify if something has been appropriately regulated because the technology and the regulatory framework are often both in flux (Ludlow, Bowman, and Kirk 2009). Arriving at just the right amount of regulation is exceedingly challenging and attempts to do so will often fall down to the timing of this so-called evaluation and perspective of the evaluator (Ludlow, Bowman, and Kirk 2009).

It is important to recognize that every new technology or development, no matter how beneficial or seemingly benign, presents risk in some form whether real or perceived. The creation of bicycles led to scrapes, bruises, and more serious accidents; prescription and over-the-counter drugs frequently have adverse side effects, and there are reports that cell phone use leads to cancer. Yet despite these harms, each of these provides great value to society. The challenge for regulators is to determine the level of risk posed – frequently with little empirical data on the potential risks – in comparison to the possible benefits to society. This cost/benefit analysis occurs at multiple different points in a development process. Prohibiting or stringently regulating in an early phase of development could directly prevent or be cost-prohibitive to those researching, inventing, and improving a product or process. Such action stifles innovation and prevents progress. In many circumstances, like in the case of bicycles, we as a society have accepted a certain level of risk of harm in exchange for the benefits provided.

However, the desire to promote innovation has limits. When public safety is in clear, obvious danger, any use could have serious negative repercussions. The classic example is the government stepping in when a person shows signs of attempting to build a bomb in his garage. In such circumstances, the potential value is negligible and harm great. The challenge is finding where the line between acceptable and unacceptable risk lies – somewhere between bicycles and bombs. There are many points in the spectrum where the line becomes less clear, such as when tinkering in the name of innovation involves animals, may inspire curious children to take risks, or when experimentation could impact third parties.

Fortunately, today we do not need to define this line; we believe DIY tDCS lies squarely in the ‘bicycle’ realm. This is not to say there are no possible dangers, but that based on the existing body of scientific evidence, such risks are personal, reasonable, and manageable, and do not outweigh the potential benefits for some individuals. Claims of DIY tDCS success stories range from mental health to improved memory and learning ability. If there is even slight truth to these claims, DIY tDCS could markedly improve the quality of life for some individuals. Dramatically so in the case of those individuals with brain injury and depression who respond positively to tDCS treatment. In contrast, testing results have not demonstrated any substantial need for alarm at this point. The harm from allowing DIY tDCS experimentation to proceed seems less substantial than the harm suffered from loss of the body of knowledge and potential therapeutic benefits from continuing discovery. Of course at any point should it become clear that there are serious health risks associated with tDCS, this balance will no longer weigh in favor of advancing the body of knowledge and regulators may need to take action.

In reading The Electric Brain, we are reminded of other DIY therapies that have been sprouted to the public, through one medium or another, all of which claim to improve health or ameliorate painful conditions. One ‘therapy’ that may provide an analogy to tDCS is the use of the ‘shoe-fitting fluoroscope’ in shoe sales departments in the early to mid-twentieth century in the United States and Great Britain (ORAU n.d.). When shopping for shoes, people of all ages were invited and encouraged to step into a ‘fluoroscope’ – a box fitted with an X-ray tube and viewing windows (ORAU n.d.). Information from the X-ray image was used to select the most suitable shoes. The fluoroscopes certainly had a novel, hi-tech appeal and probably were welcomed by people who truly had trouble getting a good fitting shoe. Unfortunately, a foot X-ray provides no information useful to shoe-fitting that is not readily evident from visual inspection and physical measurement of the foot, and the device grew to be viewed as a sales gimmick by people in the industry (ORAU n.d.). Alarm and warning against the use of the device due to concerns about radiation exposure were sounded as early as 1950 by medical professionals (Lewis and Caplan 1950). Several US states had banned or regulated the shoe-fitting fluoroscope by 1970 and the device fell out of use in the United States and Great Britain (ORAU n.d.). There are no definitive studies and no evidence that use of the shoe-fitting fluoroscope resulted in any specific cancers or higher rates of cancer among shoe-buyers (ORAU n.d.). The shoe-fitting fluoroscope was a case of the danger becoming known and the device regulated by law or by the industry before extensive public harm occurred.

Or could it be that tDCS is more akin to copper bracelets advertised to provide arthritis relief? Journalist Glenda Taylor (2013) says the ‘proposed benefits [of copper bracelets] focus on reducing joint inflammation and easing pain’ but no scientific evidence backs this up. The theory behind the bracelets’ efficacy is the transdermal uptake of minerals that support joint health (Weathers 2015). The bracelets can cause skin irritation for some people (Taylor 2013) and may be quite dangerous to the very small number of people with Wilson’s disease – a rare inherited disorder that causes too much copper to accumulate in the liver, brain, and other vital organs (Mayo n.d.). These are specific populations that can readily self-select to avoid copper bracelets. All-in-all, the bracelets are innocuous if not potentially helpful as a placebo for the large majority who endure arthritis, and probably rightly not regulated for any reason of safety or health.

D. Difficulty regulating

In contemplating government intervention in DIY tDCS technology, it quickly becomes clear that DIY tDCS would be extremely difficult to regulate. First, the device can be constructed from readily available components by following a step-by-step guide available on YouTube (address: https://www.youtube.com/watch?v=X8PFqNTcrdA). Internet or other public discussions of how to construct a tDCS device cannot be regulated under any existing statute in the way that something like bomb-making can be. In the United States, explosives are regulated under the authority of existing law by the Bureau of Alcohol, Tobacco, Firearms and Explosives (U.S. Department of Justice 2012). No parallel legal authority has been granted to any government agency to regulate the use of low-voltage stimulation devices. And second, even absent the reddit forum discussed by Smith, there are plenty of people who remember elementary school science experiments and shenanigans that included inducing electric current in a paper towel tube with a magnet and licking 9-volt batteries to feel that tingle on the tongue. In short, electricity is too fascinating and accessible for curious lay persons not to tinker with. And while people have certainly been electrocuted to the point of serious injury and even death, the voltage supplied by a 9-volt battery typical of tDCS devices and the current that flows across the head or other body regions during tDCS will not cause serious electrocution injuries.

If evidence of widespread or particularly grievous harm among users comes to light, then the discussion of regulation may become germane based on the known risks. At that juncture, we could imagine regulation of the sale or possession of tDCS devices, similar to illegal drug paraphernalia. Alternatively, because the tDCS devices can be constructed from readily available components, the sale of those components might be regulated, similar to restrictions that exist in many jurisdictions on the sale of cold medicines that contain ingredients used in the manufacture of methamphetamine. At this time, given that the devices are readily constructible and used in the privacy of people’s homes, and that there is no evidence of serious health risk, regulation seems both challenging and unnecessary.

A third reason DIY tDCS is difficult to regulate at this time is that the devices that are manufactured for sale do not fall within any category of current regulations. Certain contexts already have applicable regulations. For example, when used in clinical research trials, they are regulated to an extent. In Steenbergen’s research, she noted compliance with Netherlands’ Federal Code of Regulation’s testing standards for electronic equipment (Steenbergen et al. 2016). Similarly, if tDCS devices were to be marketed as medical devices, this would bring them under the jurisdiction of the Food and Drug Administration (FDA) in the United States, the Medicines and Healthcare Products Regulatory Agency in England, or equivalent agency in other nations. If the clinical promise of tDCS pans out and it is developed as a medical therapy, at the point that tDCS devices are sold and marketed as medical devices providing health treatments, they will be subject to FDA (or internationally equivalent) regulations that proscribe who can provide the treatment, how many treatments of tDCS are appropriate, which populations are at greatest risk, etc. At the moment though, it is simply too early for regulators to begin making determinations on these unknown factors and in the further-out-of-regulatory-reach-DIY context.

In spite of the lack of evidence of health and safety risks and the challenges to be faced in attempting to regulate DIY tDCS, some researchers already have embarked on a path toward regulation based on professional concerns like those raised by Smith. Fellows at Oxford University have called for regulation of tDCS and other cognitive enhancement devices (CEDs) under the Medical Devices Directive or a new directive specific to CEDs rather than the General Product Safety Directive where they currently fall (Maslen et al. 2014). These researchers lay out a systematic approach to regulating CEDs in the European Union that includes gradated regulation, prohibition of high-risk devices, criminal sanctions, and special protections for children. They also have recommendations for the United States and other jurisdictions, and for manufacturers of CEDs. Any path toward regulation is rightly a difficult and studied one. Information available at this time points toward slow advancement in that direction for the DIY use of tDCS.

E. Moving forward: DIYer beware

In a perfect world, DIYers would have the scientific background and access to universally agreed-upon research results to make informed decisions about their tDCS use. Unfortunately, many users have little more than a YouTube link or reddit page for guidance, and a cursory internet search for safety information produces varied opinions. However, Smith’s suggestion that neuroscientists should take it upon themselves to inform the public may not be the solution to preventing potential tDCS-use risks. Imposing a duty on neuroscientists to spread the word to potential tDCS users may be more of a burden than benefit. Where would they begin? Who would they speak to? Would this ethical obligation extend to every potentially risky new technology or medicine? Even more problematic, what would they say since the research does not support the conclusion that tDCS is a pressing danger. If neuroscientists feel personally compelled to warn people about the potential risks suggested by Smith, of course they are free to share their thoughts, but we believe there should be no ethical or professional obligation to do so.

Instead, neuroscientists can best advance the cause of promoting safety by continuing to conduct long- and short-term research on the effects of tDCS. Rather than relying on anecdotal Internet testimonials, a robust body of scientific studies can help facilitate the understanding of DIY tDCS benefits and dangers. And publication in peer-reviewed journals is the obvious way neuroscientists can spread their findings at this time.

Until there is more information, smart DIYers should approach tDCS with skepticism and carefully consider the disclaimers made by the reddit posters. Just as an individual is free to take a spoonful of honey and a glass of lemon water to attempt to cure a cold, at home DIYers may attempt tDCS use for therapeutic benefits. But in both cases there is a certain understanding that there is no guarantee of results. Further, no one is guaranteeing their safety in the process.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Lane Conrad is a J.D. candidate, class of 2018, at the Sandra Day O'Connor College of Law.

Nancy Craig is a J.D. candidate, class of 2019, at the Sandra Day O'Connor College of Law.