tDCS Research in a World With FDA Regulation

Wexler and Hamilton's (2017) editorial on crowdsourced transcranial direct current stimulation (tDCS) research discusses the potential for such research to produce scientifically valuable information, the methodological obstacles to it actually doing so, and related ethical concerns. For example, a central concern is that because of the variability in the devices themselves and in what individuals aim to achieve through their tDCS use—including a range of enhancement and treatment goals—it may be difficult to draw any general conclusions from aggregated information about individual use. Wexler and Hamilton ultimately observe that some entity would need to take control over crowdsourced tDCS research to overcome the myriad methodological obstacles.

Building on their observations, this commentary begins to explore how U.S. Food and Drug Administration (FDA) regulation of tDCS products might affect both industry-sponsored and crowdsourced studies of commercially produced tDCS products intended for home use. Specifically, this commentary makes the case that the FDA exercising its authority to regulate in this area may have informational benefits by incentivizing greater research rigor. If realized, these benefits would be socially valuable because there is great hope for and hype about tDCS use, and consumers, currently, can access these products with relative ease. However, few clinical trials have studied the home use of tDCS (Bikson et al. 2016) such that its efficacy and long-term safety are uncertain.

THE FDA'S AUTHORITY

tDCS products currently exist in something of a gray regulatory area in the United States because extant federal and state laws that could apply to commercially marketed tDCS products generally have not been enforced (Wexler 2015). The Federal Food, Drug, and Cosmetic Act (FD&C Act), the FDA's enabling statute, is one such law. There is little question that commercial tDCS products marketed for disease treatment (e.g., for depression) meet the law's definition of devices subject to the FDA's authority. But perhaps less intuitively, tDCS products marketed for wellness and enhancement, whether cognitive or physical enhancement, likewise generally meet the definition of devices within the FDA's jurisdiction (Wexler 2015; Zettler 2016). This is because, under the FD&C Act, FDA-regulated devices include products “intended to affect the structure or any function of the body,” and the FDA has long interpreted the kinds of claims that wellness and enhancement tDCS companies typically make—such as “increase your attention span” or “activates the motor cortex”—to constitute such structure/function claims (or even to be implied disease treatment claims, in certain contexts) (Zettler 2016). The FDA, therefore, has broad authority to regulate commercial tDCS products, whether they are marketed for enhancement, wellness, or conventional medical uses.

EXPLORING THE IMPACT OF FDA REGULATION ON tDCS RESEARCH

A 2015 public workshop suggests that the FDA might be considering exerting its authority in the tDCS space. The prospect of FDA regulation of commercial tDCS products raises numerous questions (Zettler 2016), including how FDA oversight would affect research on these products. One answer might be that FDA oversight would help to encourage scientifically credible industry-sponsored and crowdsourced studies of commercial products—an effect that would be most apparent for industry-sponsored research.

Devices are subject to varying FDA requirements depending on their risks, with higher risk devices subject to stricter controls and some form of premarket review. Because tDCS devices have the potential for negative long-term effects on the brain (although, thus far, seemingly unrealized) (Bikson et al. 2016; Maslen et al. 2014), companies are likely to be required to obtain agency authorization to market their products through one of several regulatory pathways—including premarket approval (PMA) or premarket notification (510(k)). Which particular premarket authorization pathway a given product will follow will depend on various factors. But regardless of a product's particular pathway to marketing authorization, a company may be required to submit meaningful safety and effectiveness data to obtain FDA marketing authorization because tDCS devices’ technological characteristics and indications may differ from those of previously FDA-authorized, noninvasive electric stimulation devices.

Such a requirement would encourage industry to conduct research designed to produce scientifically credible information. Although certain home-use tDCS companies have made data available on their websites, the absence of FDA review or peer review may raise suspicions as to whether those data provide strong scientific support for companies’ claims about their products. For example, the scientific evidence that dietary supplement companies develop to support structure/function claims about their products—which, as with tDCS products in the current regulatory environment, are not subject to FDA premarket evaluation—frequently has been found to be of low quality. Indeed, although the FDA's premarket authorization authority for drugs and devices is often understood as a mechanism for protecting patients and consumers from unsafe and ineffective products, it is also a critical tool for incentivizing industry to conduct rigorous research that creates meaningful information about the effects of their products (Eisenberg 2007).

Although not as straightforward an incentive in the context of crowdsourced research, FDA oversight may also encourage those involved in such research to mitigate the methodological limits of the research to the extent feasible. The FDA, arguably, relies on crowdsourced research in certain contexts. For example, the agency's MedWatch program, which allows patients and consumers to voluntarily report problems associated with medical products, has been characterized as a means of collecting crowdsourced observational data (Darrow 2014). Similarly, if the kinds of crowdsourced research that Wexler and Hamilton (2016) discuss were sufficiently sound (and focused on relevant commercial products), the FDA might find regulatory uses for the information that research produced. Affecting the FDA's decision making seems most plausible in contexts in which the agency has suggested that it is willing to consider “real world evidence” in its regulatory decisions for devices, such as postmarket monitoring (FDA 2016). This potential to influence the FDA's thinking and regulatory decisions may motivate patients and consumers to collectively attempt to address some of the methodological concerns about crowdsourced research. Alternatively, and perhaps the more likely outcome, the potential for such research to affect the agency's decisions may create incentives for companies to become more involved in influencing how crowdsourced research is carried out.

CONCLUSION

Although crowdsourced studies of tDCS use may seem an appealing way to derive information from what consumers are already doing, they are an unlikely source of scientifically sound information because of various methodological and ethical concerns. To the extent that there is useful knowledge to be gleaned, however, FDA regulation may be one way to motivate those involved to address the concerns about crowdsourced research to the extent possible. A more certain informational benefit of FDA oversight of commercial tDCS products may be that such regulation would give commercial tDCS companies a compelling reason to conduct scientifically sound research on the effects of their products. Although FDA oversight in this area raises numerous questions and possibly concerns about regulatory burden, the potential informational benefits to FDA involvement are worth consideration.

CONFLICTS OF INTEREST

The author served as an attorney in the Food and Drug Administration's Office of the Chief Counsel from 2009-2013. ▪