Buyer beware. For US$249 a company in the United States is promising to send curious and competitive players of computer games an unusual headset. The device, the company claims, will convert electronic gamers into electronic-gamers. At the touch of a button, the headset will send a surge of electricity through their prefrontal cortex. It promises to increase brain plasticity and make synapses fire faster, to help gamers repel more space invaders and raid more tombs. And, according to the publicity shots on the website, it comes in a choice of red or black.

The company is accepting orders, but says that it will not ship its first headsets to customers until next month. Some are unwilling to wait. Videos on the Internet already show people who have cobbled together their own version with a 9-volt battery and some electrical wire. If you are not fussy about the colour scheme, other online firms already promise to supply the components and instructions you need to make your own. Or you could rummage around in the garage.

That’s ‘could’ as in ‘you might be able to’, by the way; not ‘could’ as in ‘it’s a good idea’. In fact, to try to boost cognitive performance in this way might be a very bad idea indeed. Would it work? It might or it might not. Nobody knows. All we know for sure is that the technology, known as transcranial direct-current stimulation (tDCS), is likely to soon get into the hands, and onto the heads, of many more people.

Experimentation with electricity to improve human performance is not new. Scribonius Largus, court physician to the Roman emperor Claudius, suggested in ad 46 that a live electric ray could be applied to the head of a patient with a headache. The recent surge in interest in tDCS piggybacks on an increasing number of academic studies of its potential to boost cognitive ability, which themselves build on decades-old work using electrical stimulation of the brain to treat ailments such as depression (see Nature 472, 156–159; 2011).

Nor are unorthodox tests of this technology unusual. When Michael Nitsche, a clinical neurologist at the University of Göttingen in Germany, wanted to investigate a related technique called transcranial magnetic stimulation more than a decade ago, he got permission from university ethics boards but still found a shortage of volunteers. Instead, Nitsche experimented on the brains of himself, his father and his sister.

The scale of at-home tDCS use is unclear at present.

In an opinion piece published earlier this month, Nicholas Fitz and Peter Reiner of the National Core for Neuroethics at the University of British Columbia in Vancouver, Canada, argue that scientists and regulators can no longer ignore the amateurish meddling with tDCS (N.FitzandP.ReinerJ.Med.Ethics;2013). “The challenge for the field,” they write, “is to develop policy that thoughtfully deals with the issues stemming from people using tDCS devices at home.”

Such home use of experimental laboratory kit puts neuroethicists, and journals such as Nature, in a bind. To draw attention to it could promote and accelerate its use, and so increase the risk of a mishap. To ignore it leaves the risks unexplored. The scale of at-home tDCS use is unclear at present. It might fizzle out. Or, as scientific interest in the power of electrical stimulation of the brain grows, it might appeal to more enthusiasts, just as the fascination and potential of synthetic biology has spawned a parallel DIY community known as biohackers. The scientific interest is certainly there.

Last month, researchers at the University of Oxford, UK, published a study suggesting that random electrical stimulation of the brain could improve mathematical abilities (A. Snowball et al. Curr. Biol. 23, 987–992; 2013). And there is no lack of exposure. Drawn by the ease of access and the killer copy, science journalists are queuing up to try tDCS for themselves and to write about the effects.

Fitz and Reiner are not the first to raise concerns over the DIY tDCS community. Brain researchers flagged the problem last year, as part of a discussion on the broader ethics of using non-invasive brain-stimulation (R. Cohen Kadosh et al. Curr. Biol. 22, R108–R111; 2012). The researchers even raised the prospect of the ultimate in pushy parents: those who would use the technology on their children to try to boost their cognitive function. And back in 2011, scientists working on tDCS told Nature that they were concerned for the safety of those who tried it at home.

It is easier to raise these questions than to answer them. Fitz and Reiner have some sensible suggestions, ranging from greater reporting of the possible long-term risks of tDCS to mimicking the open communication and education strategy with which the life-sciences field has started to engage biohackers. The first step is to acknowledge the issue to get a sense of how widespread the demand for home electrical self-improvement really is. The next few months will tell us more.