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In the last decade or so there has been increasing research into non-invasive brain stimulation techniques for a variety of conditions. These include transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), random noise stimulation (tRNS), and transcranial magnetic stimulation (TMS). These techniques alter the excitability of neurons in the brain, seem to have an effect on plasticity (the ability to form new connections), and can modulate the activity of brain networks.

Overall the current research is preliminary but encouraging. Many of the details of exactly how to apply this new technology, however, are still being worked out. One recent review summarizes this complexity:

tDCS can be used to manipulate brain excitability via membrane polarisation: cathodal stimulation hyperpolarises, while anodal stimulation depolarises the resting membrane potential, whereby the induced after-effects depend on polarity, duration and intensity of the stimulation. A variety of other parameters influence tDCS effects; co-application of neuropharmacologically active drugs may most impressively prolong or even reverse stimulation effects. Transcranial alternating stimulation (tACS) and random noise stimulation (tRNS) are used to interfere with ongoing neuronal oscillations and also finally produce neuroplastic effects if applied with appropriate parameters.

In other words – exactly where the electrodes are placed on the scalp, how strong the stimulation is, how long it is applied, and the details of the pattern of electrical activity all potentially affect the net effect on brain function. Anodal tDCS stimulated neuronal firing, while cathodal tDCS inhibits function. Further, there are differences in terms of who is receiving the treatment (someone who is neurologically healthy vs. someone who recently had a stroke), and what other treatments are being given concurrently – such as physical therapy and pharmacotherapy.

Overall this does not seem like the kind of treatment that should be given over-the-counter. That is exactly what is happening, however.

For example, a product called foc.us is being sold with the following claims:

foc.us is a tDCS headset for gamers

Overclock your head!

Overclock your brain using transcranial Direct Current Stimulation (tDCS) to increase the plasticity of your brain. Make your synapses fire faster.

Faster Processor, Faster Graphics, Faster Brain!

They also address the question of whether or not the device is regulated:

No. The foc.us gamer headset offers no medical benefits, is not a medical device, and is not regulated by the FDA.

The FDA does regulate medical devices, including some cranial electrotherapy stimulation (CES) devices. But, according to the FDA, “There is no regulation for therapeutic tDCS,” which it does not consider a CES device because it is too different.

It is very problematic to claim that a device that is explicitly medical in nature is “not a medical device” simply because the claims currently being made for it are performance enhancement, rather than treating a disease or condition. This strategy does not work for drugs. I doubt the FDA would buy the argument that amphetamine is not “medical” if used for performance enhancement.

It seems to me that foc.us is exploiting the current holes in FDA regulations, which have not yet dealt with devices such as tDCS.

Regardless of regulation, I would argue that tDCS technology is not ready for the general consumer.

Effects of tDCS are promising, but largely preliminary. There are studies looking at the treatment of depression, rehabilitation from stroke, and pain relief. Results seem most encouraging for stroke recovery, less so for depression, and are leaning negative for pain relief (but again, this does not necessarily apply to all forms of brain stimulation). In all cases results should be considered preliminary.

In terms of cognitive performance, studies are again preliminary with mixed results, some showing little or no benefit.

All of the studies do tend to agree, however, that tDCS is safe. Potential side effects include local itching or tingling, headache, a burning sensation, and discomfort. However, better reporting of adverse events to more thoroughly evaluate potential side effects is also being recommended.

Conclusion

tDCS is an interesting and potentially very useful treatment designed to alter brain activity, with potential applications to depression, motor function, cognitive function, and pain. Its application is complex, however, and researchers are still working out the effects of numerous parameters.

In my opinion, tDCS is not ready for the over-the-counter market, nor the DIY community. Our knowledge base is simply not detailed enough. Further, even if we did have detailed knowledge of optimal placement, frequency, intensity, duration, etc. it would be difficult for the average user to get all these details correct. Even if these parameters could be fully automated, there is still the issue of the individual medical history of each user and how that might impact the safety and usefulness of tDCS. Meanwhile, regulations lag behind the technology and may never be aggressive.

While generally safe (although more safety data is needed), we still do not have enough information about the net effects of using this technology in various conditions for a long period of time.

It is likely that for the foreseeable future consumers will have to protect themselves from companies selling tDCS devices with unsubstantiated claims. At present I recommend caution.