Kids who once relied on traditional ADHD medications like Adderall and Ritalin now have a new option at their disposal that looks nothing like a pill. This new device is a pocket-sized electric pulse machine that delivers an almost imperceptible tingling sensation to the head. On Friday, it became the first ever FDA-approved medical device to treat ADHD in children, even though it’s not clear exactly how it works.
The $900 prescription-only device, called Monarch eTNS, is manufactured by NeuroSigma, a life sciences company in Westwood, California. The FDA’s statement says that Monarch eTNS, a “cell-phone sized” device with an external patch that attaches to the forehead, is specifically designed to treat children between the ages of 12 and 17. The patch delivers stimulation that create a “tingling sensation” on the skin between the eyebrows.
The device is already used to treat epilepsy and depression in Canada and the European Union. Now, it has the FDA’s stamp of approval to treat the estimated 6.1 million kids under 17 who have ADHD in the United States and has opened the regulatory door to devices like it, though there is currently only a working theory for how and why it works.
How Does Monarch eTNS Monarch Work?
Monarch eTNS delivers a slight electric pulse to the trigeminal nerve in the brain, a large cranial nerve that transmits sensory information to the face. According to the FDA, the pulses travel through that nerve and help convey “therapeutic signals to the parts of the brain thought to be involved in ADHD”. But how those therapeutic signals work to reduce ADHD symptoms remains up for debate.
“While the exact mechanism of eTNS is not yet known, neuroimaging studies have shown that eTNS increases activity in the brain regions that are known to be important in regulating attention, emotion and behavior,” says the FDA.
Nevertheless, the impulses seem to have an effect on ADHD symptoms, as demonstrated in several studies, the most recent being a clinical trial published in April in the Journal of the American Academy of Child and Adolescent Psychiatry. In that clinical trial, led by UCLA’s James McGough, Ph.D., a professor of clinical psychiatry, the 32 children who used the device each night for four weeks while they slept found significant improvements in measures of ADHD symptoms than the group of 30 who used a placebo device.
In that paper, McGough and his colleagues propose that the device stimulates the fronto-basal ganglia network. This loop of neurons helps control what they call the “outright stopping of an action” — like when a deer jumps out into the middle of the road and you suddenly have to hit the brakes. A theory put forth in a 2017 study published in Neuron and cited by McGough is that the fronto-basal ganglia network helps us decide, at the last second, not to do something.
In the paper submitted as part of his clinical trial, McGough hypothesizes that his treatment works for the hyperactivity in ADHD because this idea can also be applied to impulsive behavior present in children with ADHD. He suggests the device stimulates the brain regions involved in the fronto-basal ganglia network and in doing so created “subsequent improvement in hyperactive and impulsive behaviors.”
The Significance of eTNS in Future ADHD Treatment
Using the device may come with some side effects — notably, increases in appetite, drowsiness, trouble sleeping, fatigue, teeth clenching and headache — which the FDA and McGough both report. But as of now, no one has reported any serious adverse events. So far, its safety and effectiveness suggest it is likely to become the first of many more devices like it, with the FDA noting that its approval sets a new regulatory precedent:
This action creates a new regulatory classification, which means that subsequent devices of the same type with the same intended use may go through the FDA’s 510(k) premarket process, whereby devices can obtain marketing authorization by demonstrating substantial equivalence to a predicate device.
This means that the device’s approval has set a precedent for other medical devices that work the same way that will allow them to jump through the FDA’s regulatory process faster, if their creators can show “substantial equivalence” to the Monarch eTNS:
If they succeed, the FDA can clear that new technology for commercial distribution. For now, a cell phone-sized electric stimulator that tells the brain to stop might seem weird, but eTNS is a model that many more devices may soon follow.