An unusual new treatment for Tourette’s syndrome involves applying an electrical current to the wrist, which travels up nerves to the brain and changes brainwaves. The approach, which moderately reduced the number of tics in volunteers with Tourette’s, suggests the condition is linked with an underactivity in brainwaves that normally keep us still.
People with Tourette’s syndrome make frequent involuntary jerks, facial twitches and noises. Tics usually arise around the age of 6, and while they often fade with time, for some they continue and can be debilitating. “Sometimes children literally break bones because they’re flinging themselves around so much,” says Stephen Jackson at the University of Nottingham in the UK.
In most people, when they are motionless, brainwaves cycle at about 12 times a second in part of the brain called the motor cortex, located at the top of the head. “It’s like the handbrake on a car – it maintains a stable posture,” says Jackson.
Previous research has shown that stimulating brainwaves in this area by using a strong oscillating magnetic field above the head can reduce tics in people with Tourette’s. Jackson wondered if there was a way to get this effect more easily.
His group placed an electrode on the wrist to deliver a mild current with a frequency of 12 times a second; the current was noticeable but not uncomfortable. The idea is that this current travels via nerves to the sensory cortex of the brain and induces oscillations at the same frequency in the neighbouring motor cortex.
When 19 people with Tourette’s tried out the electrode, it reduced the frequency of their tics by a third, compared with when the electrode was turned on for the same length of time but had no regular frequency. Voluntary movements were only slowed a little.
Normally people with Tourette’s feel an urge to tic slowly building until it becomes irresistable. Many of the volunteers reported that when the electrodes were at the right frequency, their urges reduced. Charlie, a 21-year-old with severe tics, said in a statement: “When the electrical pulses on the wrist started to increase, the tic urges decreased, which was a completely shocking experience for me, I was silent and still. I wanted to cry with happiness.”
Jackson’s group is developing a watch-like device that people can turn on to deliver the stimulation when it is needed.
Journal reference: Current Biology, DOI: 10.1016/j.cub.2020.04.044