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NeurostimulationHacking your brain

With a
DIY bundle of electronics or a ready-made device it is possible to stimulate the
brain. But does it work and is it safe?

Print edition |
Technology Quarterly
Mar
5th 2015

“IT’S like coffee times ten,” raves one enthusiast. “I use
it a couple of times a week and problems solve themselves. At the end of the
day, I haven’t wasted hours on frivolous websites. At the end of the week, my
apartment is clean.” This marvel of productivity is not a new energy drink or an
experimental wonder drug but a simple electrical device that he built at home
for less than $10. Whenever this physicist feels like an extra burst of
motivation, he places electrodes on his skull and sends a jolt of electricity
into his brain.

The currents, which are typically applied for ten to 20
minutes, are hundreds of times smaller than the seizure-inducing shocks used in
electroconvulsive therapy. Plans to make such transcranial direction current
stimulation (tDCS) machines are freely available online and their components can
be bought at hobbyist stores. Kits cater to those lacking soldering skills, and
now companies are emerging offering nicely designed and packaged brain zappers
for mainstream consumers.

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Not everyone using tDCS is seeking to become more
efficient in their daily life. Some hope to enhance their concentration for
study or video gaming; others want to boost their memory, speed up learning or
induce meditative calm. Yet more are trying to self-medicate for conditions such
as depression, chronic pain and motor, sensory or neurological disorders. The
benefits might sound implausible, but there is some science to support them. The
idea goes back a long way. Scribonius Largus, a first-century Roman physician,
prescribed the shock of an electric ray for headaches, and in the 19th century
electrical pioneers such as Luigi Galvani and Alessandro Volta toyed with crude
bioelectric experiments. It was not until the 1960s, however, that the first
rigorous studies of electrical brain stimulation took place.

Directing the flow

The theory behind tDCS is that a weak direct current
alters the electric potential of nerve membranes within the brain. Depending on
the direction of the current, it is said to make it easier or more difficult for
neurons in a brain circuit to fire. Position the electrodes correctly and choose
the right current, so the idea goes, and you can boost or suppress all kinds of
things. Some researchers have reported that tDCS can reduce pain, ease
depression, treat autism and Parkinson’s disease, control cravings for alcohol
and drugs, repair stroke damage, and accelerate recovery from brain injuries, to
say nothing of improving memory, reasoning and fluency. Remarkably, some effects
seem to persist for days or even months. And the closer that scientists look at
tDCS, the more they seem to find. Scientific papers about the technology appear
at an ever-faster rate.

Hardly surprising, then, that DIY brain hackers want in on
the action. Christopher Zobrist, a 36-year-old entrepreneur based in Vietnam, is
one of them. With little vision he has been registered as blind since birth due
to an hereditary condition of his optic nerve that has no established medical
treatment. Mr Zobrist read a study of a different kind of transcranial
stimulation (using alternating current) that had helped some glaucoma patients
in Germany recover part of their vision. Despite neither the condition nor the
treatment matching his own situation, Mr Zobrist decided to try tDCS in
combination with a visual training app on his tablet computer. He quickly
noticed improvements in his distance vision and perception of contrast. “After
six months, I can see oncoming traffic two to three times farther away than
before, which is very helpful when crossing busy streets,” he says.

Online communities dedicated to tDCS are full of similar
stories. More still claim to have gained cognitive enhancements that give them
an edge at work or play. Users follow the latest scientific papers avidly and
attempt to replicate the results at home, discussing the merits of different
currents, waveforms and “montages” (arrangements of the electrodes on the
skull).

Happiness and health may always be
more than just a 9-volt battery away

Dissenting voices are rare. Here and there are tales of
people who experienced headaches, nausea, confusion or sleeplessness after tDCS,
while temporary visual effects and mild skin burns are fairly common. There have
been no reports of seizures, serious injuries or deaths. But that does not mean
it is without risk, says Peter Reiner, co-founder of the National Core for
Neuroethics at the University of British Columbia. He says DIY users may place
electrodes incorrectly, thus stimulating the wrong part of their brain, or
reverse the polarity of current, potentially impairing the very things they are
trying to improve. No one really knows how tDCS interacts with chemical
stimulants or recreational drugs like marijuana, or with pre-existing conditions
like epilepsy. Even something as fundamental as being left-handed can alter the
functional organisation of the brain. And if the benefits of tDCS can persist
for weeks, perhaps its side-effects can linger, too. Many neuroscientists are
particularly worried that the use of tDCS by children and young adults could
affect their long-term neural development.

Some of these concerns can be addressed by manufacturing
tDCS devices to make it difficult, or impossible, to exceed recommended currents
or to apply the electrodes incorrectly. One such product already exists. The
Foc.us V2, made by Transcranial, a London company, is advertised as a $199
pocket-sized controller that pairs with a $99 headset intended to help with
concentration and reaction speed while videogaming. Donning the headset
automatically positions the electrodes on the left and right temples, and both
the duration and maximum current are capped. A second headset provides a
different montage aimed at improving performance and motivation while
exercising.

In reality, however, there is no guarantee that even slick
products are any safer than a pocket-money brain stimulator assembled at home
from a 9-volt battery, electrodes, a few wires and other components. Unlike the
tDCS machines used for medical trials and clinical research, consumer versions
may not have been assessed by any official body for safety or effectiveness. If
the maker insists they are for use only by healthy adults to enhance cognition
or leisure activities and make no diagnostic or therapeutic claims, such
“wellness” devices have slipped under the regulatory radar of both the Medical
Devices Directive in Europe and the Food and Drug Administration (FDA) in
America.

That worries some experts. A recent paper from the
Institute for Science and Ethics at the University of Oxford points out that
consumer tDCS products are mechanically and functionally equivalent to medical
neurostimulation devices that require licensing. Why regulate the version that
is likely to be operated responsibly by health professionals, and not the one
freely available to unskilled and inexperienced users? The Nuffield Council on
Bioethics agrees, recommending in 2013 that the European Commission should
consider regulating all such gadgets under its medical devices regime,
regardless of the purposes for which they are marketed.

The Institute for Science and Ethics proposes a graded
regulation system that errs on the side of consumer choice for tDCS devices,
requiring comprehensive, objective information about risks and benefits to allow
users to make informed decisions. But it wants supplying brain zappers to
children to be made illegal. Last year the FDA allowed transcutaneous electrical
nerve stimulator (TENS) machines for headache relief as it rated them as low-to
moderate-risk devices. TENS devices use a different waveform to tDCS and target
cranial nerves rather than the brain itself, but they rely on a similar
controller and head-mounted electrodes. Before allowing new TENS products to be
sold, the FDA now wants to see evidence that the components are not likely to
cause injury, that the controller can reliably provide the correct output, that
there are no thermal or mechanical hazards, and that clinical data demonstrate
the device is safe and effective as a headache treatment. Recent draft FDA
guidelines for wellness devices suggest tDCS machines may eventually be
regulated in a similar way.

Going underground

The University of British Columbia’s Dr Reiner doubts that
any manufacturer today can provide such information for tDCS. Even if they
could, the cost of gathering it would make consumer devices more expensive.
“When you can make a tDCS device yourself for less than $20, we would advise
strongly against heavy regulation because it will only drive the technology
underground,” he says.

Proving the effectiveness of brain stimulation will be
difficult. Although it may well do something, exactly what is open to question.
As the hype around tDCS grows, some neuroscientists are starting to question
whether the technology really is the panacea it appears to be.

In 2013 Teresa Iuculano and Roi Cohen Kadosh of the
Department of Experimental Psychology at the University of Oxford split
volunteers up into three groups and asked them to learn a made-up mathematical
notation system. The first two groups received tDCS to different parts of the
brain previously associated with numerical understanding and learning, while a
non-functional “sham” device was used on the third group as a control. After a
week, all three groups were tested on how well they had learned the new notation
system, and whether they could use it in practice. The first group showed an
improvement in learning compared with the control group, but a decrease in their
ability to apply their knowledge, while the second group experienced the
opposite result. This suggests that the brain is actually rather well balanced:
boost performance in one cognitive realm through stimulation, and aptitude in
another will naturally diminish.

There is also the possibility that a variation in
individual responses to tDCS will overshadow any general effects. In a study
published last year, Dr Cohen Kadosh set up two groups: one of people who were
anxious when presented with mathematical problems, and another who had
confidence in their ability to breeze through numerical quizzes. When treated
with tDCS to their prefrontal cortices, the nervous individuals improved their
reaction time on simple arithmetical problems and showed reduced levels of
stress. Given the same treatment, the confident group had longer reaction times
and no less stress. “If you can get exactly the opposite results with a
different population, that shows DIY brain hackers and companies marketing
stimulation to improve gaming or other abilities are not on the right track,”
says Dr Cohen Kadosh. “We need to understand how the brain works in different
people.”

Felipe Fregni, director of the Laboratory of
Neuromodulation at Harvard Medical School, says tDCS has been shown to
accelerate the learning of new skills. But he agrees that individual variation
is important, noting that younger people sometimes do not improve as much as
older subjects, and that people at later stages of learning may even experience
detrimental effects. “The more science you know, the more confused you can
become of what really is the effect of tDCS,” says Dr Fregni.

One advantage of the deluge of scientific papers is that
they can be subjected to meta-analysis, whereby studies can be statistically
combined to tease out new discoveries. Last year, Jared Horvath, a
neuroscientist at the University of Melbourne in Australia, published a
meta-analysis of 30 measurements taken during tDCS studies, including neural
responses, oxygen levels and electrical activity in the brain. Surprisingly, he
found that tDCS had a reliable effect on only one: the electrical response of
muscles to stimulus, and even that has steadily declined in studies over the
last 14 years. Mr Horvath believes this indicates that the response has
historically been measured poorly and that it too will eventually disappear as
techniques mature.

Equally troublesome is a meta-analysis of the cognitive
and behavioural effects on healthy adults that Mr Horvath subsequently carried
out. As before, he included only the most reliable studies: those with a sham
control group and replicated by other researchers. It left 200 studies claiming
to have discovered beneficial effects on over 100 activities such as problem
solving, learning, mental arithmetic, working memory and motor tasks. After his
meta-analysis, however, tDCS was found to have had no significant effect on any
of them.

If tDCS alters neither the physiology of the brain nor how
it performs, thinks Mr Horvath, then evidence suggests it is not doing anything
at all. Marom Bikson, a professor of biomedical engineering at City University
of New York, disagrees. “I can literally make you fall on your butt using the
‘wrong’ type of tDCS,” he says. Dr Bikson thinks the biggest challenge for tDCS
is optimising techniques, such as the dose.

Mr Horvath notes that many papers measure 20 or more
outcomes, with brain stimulation showing a weak effect on one or two. “But in
the title and abstract, that’s all they talk about,” he says. “No one mentions
the tons of effects that tDCS didn’t have an impact on but that technically it
should have if it is doing what the researcher thinks it is.”

Another problem might be the small sample size, sometimes
as few as ten or 15 people. Mr Horvath says future studies should use at least
150 subjects. There is, of course, the possibility that Mr Horvath’s analyses
are flawed. His paper included only one-off sessions, while many scientists
believe the effects of tDCS accumulate with repetition. However, too few
multiple-session studies exist for a valid meta-analysis. Dr Cohen Kadosh points
out that individual variations could make the technology look as though it is
doing nothing when in fact it has real but opposing effects in different people.
Mr Horvath insists that his analysis allows for this possibility.

Critics might also wonder why Mr Horvath omitted tests
where tDCS seems to have been most effective, in alleviating, for instance,
clinical conditions such as depression. He admits that would be useful but says,
“If something doesn’t demonstrate any type of effect in healthy people, it
becomes incredibly difficult, if not impossible, to argue why it would work
within a clinical population.”

Not all neuroscientists are defending the status quo. “I’m
not surprised that he found no effect from conventionally applied tDCS,” says
Jamie Tyler, a professor at Arizona State University and one of the founders of
Thync, a Silicon Valley startup that recently unveiled a smartphone-controlled
tDCS device. Thync tried to replicate some basic tDCS findings on cognition but
could not do so. Dr Tyler now believes that tDCS may not directly stimulate the
brain at all but instead modulates cranial nerves in the skull, like the
headache-busting TENS technology. He designed the Thync device, a pocket-sized
unit with disposable pre-shaped electrodes, to target these nerves with the aim
of generating either relaxed or energetic mental states.

A shot of caffeine

Dr Tyler recently published a study of 82 people with a
control. Its results suggest that Thync’s device can reduce psychophysiological
stress by altering skin conductivity (a measure used in pseudoscientific lie
detectors), stress enzymes and heart rate variability. He likens Thync’s
“modified tDCS” programs to ingesting either a third of a cup of coffee or a
glass of wine, and says no effect has been found on cognitive processes like
working memory. While Thync’s stimulator is not yet available to the public, the
firm was willing to give your correspondent a pre-launch trial.

The Thync device attaches with one sticky electrode on the
right temple and one behind the right ear. The unit is controlled via a
smartphone app, with the user able to adjust the intensity but not the duration
of the session. At first, the unit generated a barely perceptible crawling
feeling on the skin near the electrodes, building gradually to a pronounced
tingling sensation. Over the 20-minute session, the strength of the signal
varied up and down according to a preset routine. It felt itchy at times and, at
its most powerful, caused muscles in the forehead to spasm alarmingly. Although
the experience was not altogether unpleasant, any extra energy or focus proved,
alas, elusive. Dr Tyler acknowledged that perhaps one in four people do not
perceive any immediate benefit from the device.

Even for those who find themselves susceptible to its
charms, the challenges for a product like Thync are formidable. The cognitive
enhancements of a strong cup of tea or a glass of vintage Burgundy are well
established. And partaking of them can be socially acceptable, deliciously
enjoyable and rapidly achieved. None of these can be said of a disconcerting
gizmo that needs half an hour to work and causes eyebrows to raise, both
literally and socially.

Regardless of their questionable utility and
effectiveness, tDCS gadgets are too novel, cheap and alluring to simply dismiss.
Consumer-wellness devices like Thync may appeal to those who cannot use caffeine
or alcohol for medical or religious reasons, and there will always be healthy
overachievers seeking to supercharge their cognition for study or work. More
importantly, tDCS presents the tantalising promise of relief from some medical
conditions for which traditional therapies are either ineffective or
unaffordable. As the University of Melbourne’s Mr Horvath says, “If there are
ten percent of people who are feeling a huge effect, even if that’s placebo, who
are we to say no to them?”

If people want to experiment with tDCS, there seems to be
no reason to prevent them, provided it is done in the safest way possible.
Devices could be regulated lightly with a view to safety rather than
effectiveness, and neuroscientists encouraged to design future studies with more
rigour. Happiness and health may always be more than just a 9-volt battery away,
but brain hacking looks like it is here to stay.

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