The United States has approved the first device of its kind for brain stimulation, intended for the treatment of attention deficit hyperactivity disorder (ADHD). However, its effectiveness is in doubt, as scientists believe the Food and Drug Administration (FDA) made its decision based on a study that was too limited in scope.

Searching for Alternative Treatment Methods

Researchers are actively seeking non-invasive and non-pharmaceutical therapies for conditions such as ADHD and major depressive disorder (MDD). While several promising studies on experimental treatments have already been conducted, there is still insufficient data on the effectiveness of new brain stimulation devices.

Criticism of Early Studies

This conclusion was reached by scientists from King’s College London in collaboration with colleagues from the University of Southampton, who studied a prescription external trigeminal nerve stimulation (TNS) system, approved by the FDA in 2019. The manufacturer of the Monarch device received federal approval after a trial involving 62 children with ADHD, who used the device every night for eight hours over the course of a month.

According to the researchers, the main issue was the flawed design of the experiment: the control group did not receive any stimulation, which prevented blinding and increased the likelihood of a placebo effect among device users.

A New Large-Scale Study

In a larger, multicenter study involving 150 children and adolescents with ADHD aged 8 to 18, scientists tested the device using a different methodology. Participants wore the TNS device for nine hours each night over four weeks, with battery-powered electrodes attached to their foreheads. Half of the participants received full Monarch treatment, while the others received only 30 seconds of stimulation each hour at a lower frequency and pulse width, which is considered ineffective and meets the criteria for experimental control.

Dr. Aldo Conti, a postdoctoral researcher at King’s College London and the study’s lead author, noted: “This multicenter study was designed to address the key shortcomings of the previous pilot study, on the basis of which the FDA approved TNS for ADHD treatment, particularly by using a strictly controlled placebo condition, which ensured successful blinding throughout the treatment period. Unlike the earlier work, which was limited to younger children, we also included adolescents—a clinically important group, given the known challenges with long-term adherence to medication. These decisions allowed for a more reliable and clinically meaningful assessment of TNS.”

Results and Conclusions

The study found that while the device is safe to use, it did not provide significant symptom relief in the treatment group compared to the group receiving brief stimulation. Typical ADHD symptoms were assessed, including distractibility, attention, depression, anxiety, and sleep quality.

The researchers emphasize the importance of conducting rigorous scientific trials before approving treatment methods for widespread use. Although the device was found to be safe and users considered it easy to use, it may not live up to the expectations set at the time of its approval.

Professor Samuele Cortese, the lead investigator at the Southampton site, commented: “Robust evidence, such as that obtained in this study, is essential to support shared decision-making regarding interventions for ADHD. This gives people with ADHD and their families the opportunity to make informed choices about treatment. Doctors, patients, and their families need to know which treatments work and which do not, based on the best available evidence.”

The Importance of Controlling the Placebo Effect

Current data suggest that TNS stimulation, which is thought to activate brain regions associated with attention (frontal and thalamic areas via the brainstem), could be an alternative to stimulants for treating ADHD. However, research is still in its early stages and results remain inconclusive. Controlling for the placebo effect in clinical trials is extremely important.

Professor Katya Rubia, Professor of Cognitive Neuroscience at King’s College London, emphasized: “Our study demonstrates how crucial it is to develop adequate placebo conditions in clinical trials of brain therapies. There is a pronounced placebo effect when using high-tech brain therapies, especially among patients and families who hope that brain features associated with ADHD can be corrected. Therefore, it is vital to control for the placebo effect in modern brain therapies to avoid false hopes.”

The study was published in the journal Nature Medicine.