For years, gamers, athletes and even regular people trying to improve their memory have resorted, with electrified enthusiasm, to "brain zapping" to gain an edge.
The procedure, called transcranial direct current stimulation (tDCS), uses a battery and electrodes to deliver electrical pulses to the brain, usually through a cap or headset fitted close to the scalp.
Proponents say these currents are beneficial for a range of neurological conditions like Alzheimer's and Parkinson's diseases, stroke and schizophrenia, but experts are warning that too little is known about the safety of tDCS.
"You might end up with a placement of electrodes that doesn't do what you think it does and could potentially have long-lasting effects," said Matthew Krause, a neuroscientist at the Montreal Neurological Institute.
A Montreal connection
All functions of the brain—thought, emotion and coordination—are carried out by neurons using pulses of electricity. "The objective of all neuroscience is to influence these electrical processes," Krause said.
The brain's activity can be influenced by drugs that alter its electrochemistry or by external electric fields.
While mind-altering headsets may seem futuristic, tDCS is not a new procedure. Much of the pioneering work in the field was done in Montreal by Dr. Wilder Penfield in the 1920s and 30s.
Back then, Penfield cut patients' skulls open to apply electrodes directly to their brains. By the 1960s, neuro-stimulation technology became much less invasive.
"Now, a kit can fit in your pocket. You could rig up one with a battery and cotton balls for less than $50," Krause said.
A wave of popularity
Krause said the current wave of interest in electrical neuro-stimulation research began more than a decade ago with studies that found gains in various brain functions.
He studies the effects of tDCS on monkeys with colleagues in Montreal and the United States.
"[The procedure] seems to slightly improve their memory and coordination, but we don't yet know how or why," he said. And that, according to Krause, is the crux of the problem—too much remains unknown.
While scientists are being cautious, public enthusiasm for the procedure is growing. The Internet is full of blogs extolling its benefits. A Reddit forum gives tips on how to make homemade equipment and videos of amateur brain zappers are all over YouTube.
Krause warns that there are few laws in place to protect consumers. In research settings, tDCS is strictly controlled, reviewed by peers and subject to approval by ethics committees. But it is not approved for general clinical use in Canada or the United States.
"If tDCS was sold as a medical device, it would have to jump through many hoops. But it's being sold as an enhancer, so regulatory approval isn't needed," said Krause.
"You use it at your own risk."
Too little regulation, too many unknowns
The risks can be quite serious.
"With the do-it-yourself approach, there is a risk of the current being too strong. That could trigger a seizure," Krause warned.
Other risks of tDCS are subtler. Closely-packed parts of the brain perform dramatically different functions. "Applying current to the wrong place could have negative effects," Krause said, adding that being even a few millimetres off can impair memory and performance.
Krause advised people to talk to their doctors if they are considering tDCS. He said there are lots of trials going on for many different conditions, from anxiety to Parkinson's and researchers are always looking for people to participate in their studies.
The scientific consensus is that the procedure is promising but still poorly understood.
"You only have one brain. Wait for the research to catch up with all the hype," Krause said.