Zapping your brain with electricity—known as transcranial direct-current stimulation, or tDCS—has been touted as a way to improve cognitive function and perhaps even treat mental health conditions. A study published Friday in the journal Neurology adds a new application to that list: combatting motion sickness.
"Motion sickness is quite a common problem; it affects significantly three in 10 of us, and it has the potential to affect each and every one of us," lead author Qadeer Arshad, a researcher at Imperial College London, said in a phone call. "And as of yet there's no good therapies for motion sickness."
Existing treatments tend to only be partially effective, and can have side effects such as drowsiness.
Arshad can imagine a tDCS treatment for motion sickness hitting the shelves in 5-10 years, possibly powered by your phone. "That could deliver the current required, so you could have like your plug-in headphones—you could plug in small electrodes which you could attach to yourself," he said. He imagines people using it if they were about to set off on a ferry, for example.
We still don't really know what causes motion sickness, but previous research has shown that a functioning vestibular system—the sensory system that deals with balance—is necessary to experience it.
Arshad previously worked on a study that showed tDCS over a part of the brain called the left parietal cortex could suppress this system. The new study tests if it can actually alleviate motion sickness.
Administering tDCS means attaching electrodes to a patient's scalp and applying a small amount of current to the area. In this case, 1.5 milliamps was applied via electrodes held in place with an EEG cap.
Twenty volunteers tested the treatment in a motorized chair designed to cause motion sickness by whirling around like a fairground ride. They first tried it out with a "sham" tDCS headset and then, after a period of recovery time, with the real thing. They were zapped for around 15 minutes before the chair started moving, plus during the ride.
The earlier work showed that cathodal stimulation worked to suppress the vestibular system—the cathode being the negatively charged electrode, as opposed to the anode, which is positively charged. In this case, the researchers tried both anodal and cathodal stimulation to check that held true.
It's a small sample size, but the results show promise: with cathodal stimulation, it took longer for volunteers to start feeling symptoms of motion sickness and also took them less time to recover (anodal stimulation didn't have the same effect). The researchers write: "We provide a novel treatment for motion sickness that is, so far, apparently free of side effects."
Next, Arshad says he is going to look at how tDCS could be applied to help with other kinds of motion sickness such as "virtual reality sickness," the nausea many people experience when using VR.
Let's hope they come up with a more slimline electrode cap if we're going to be wearing it under a VR headset.