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Published: January 19, 2026
LONDON — A large-scale multicenter clinical trial has found that a non-invasive brain stimulation device, previously cleared by the U.S. Food and Drug Administration (FDA) to treat Attention-Deficit/Hyperactivity Disorder (ADHD), is no more effective than a placebo.
The study, led by researchers at King’s College London in collaboration with the University of Southampton, involved 150 children and adolescents. The findings, published today in the journal Nature Medicine, challenge the clinical utility of External Trigeminal Nerve Stimulation (TNS) and suggest that regulatory bodies may need to revisit the evidence used to clear the device for public use.
A Shift in the ADHD Treatment Landscape
ADHD is one of the most common neurodevelopmental disorders, affecting between 5% and 8% of school-age children worldwide. It is characterized by persistent patterns of inattention, hyperactivity, and impulsivity that interfere with daily functioning and development.
While stimulant medications remain the “gold standard,” improving symptoms in approximately 70% of patients in the short term, many families seek alternatives due to concerns over long-term side effects or personal preference. This demand paved the way for TNS—a device that delivers low-level electrical pulses to the trigeminal nerve via a patch on the forehead during sleep.
The theory behind TNS is “bottom-up” stimulation. By activating the trigeminal nerve, signals are sent to the brainstem, specifically the locus coeruleus, which regulates arousal. From there, the stimulation is intended to reach the frontal and thalamic regions—areas of the brain often underactive in individuals with ADHD.
The Gap Between Pilot Data and Large-Scale Trials
In 2019, the FDA cleared the first TNS device for ADHD based on a pilot study of 62 children. That original trial reported significant symptom reduction after four weeks of nightly use. However, that study faced criticism for its design: the “control” group received no treatment at all, and the researchers did not test whether participants knew they were in the active or control group (a process called “blinding”).
The new UK-based trial sought to address these flaws with a more rigorous “sham” condition. Of the 150 participants aged 8 to 18, half received active TNS for nine hours a night. The other half received a sham treatment where the device looked identical and delivered just 30 seconds of stimulation per hour—enough to mimic the physical sensation without providing a therapeutic dose.
Key Findings of the New Study:
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No Significant Improvement: There was no statistical difference in ADHD symptom reduction between the active group and the sham group.
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Objective Measures: Objective tests of hyperactivity, attention, and mind-wandering showed no improvement.
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Secondary Factors: No significant changes were observed in associated symptoms like anxiety, depression, or sleep quality.
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Safety: The device was confirmed to be safe, with no serious adverse events reported, and most families found it easy to use.
The Power of the Placebo Effect
The study’s authors emphasize that the discrepancy between the 2019 FDA clearance and these new results likely stems from the “placebo effect”—the phenomenon where a patient’s symptoms improve simply because they believe they are receiving a powerful treatment.
“Our study shows how important it is to design an appropriate placebo condition in clinical trials of brain therapies,” said Professor Katya Rubia, Professor of Cognitive Neuroscience at King’s College London and senior author of the study. “There is a large placebo effect with high-tech brain therapies, in particular for patients and families that have an expectation that they can adjust brain differences associated with ADHD.”
Dr. Aldo Conti, the study’s first author, noted that including adolescents was a vital part of this research. “Adolescents are a clinically important group given well-documented challenges with long-term medication adherence,” Dr. Conti explained. “These design choices enabled a more robust and clinically relevant evaluation.”
Public Health Implications and Expert Perspectives
In the United Kingdom, the National Institute for Health and Care Excellence (NICE) has notably withheld a recommendation for TNS, citing a lack of evidence. These new findings validate that cautious approach.
Professor Samuele Cortese, a NIHR Research Professor at the University of Southampton who led the Southampton site, stressed the importance of evidence-based decision-making for families. “Clinicians, individuals with ADHD, and their families need to know which treatments work, and which do not, based on the best evidence,” he said. “Rigorous evidence… empowers individuals with ADHD and their families to make informed choices.”
For parents currently using or considering TNS, the results are a reminder that “FDA-cleared” does not always mean a treatment is the most effective option available. While TNS is safe, this trial suggests it may not provide the symptom relief families are hoping for.
Limitations and Future Directions
While the study was large and well-controlled, some proponents of TNS may argue that four weeks is too short a window to see “neuroplastic” changes in the brain. However, the trial was specifically designed to mirror the timeframe of the original study that led to the device’s clearance.
As digital and electrical “medtech” continues to explode in the mental health space, this study serves as a high-profile call for stricter regulatory scrutiny and larger, independent replication studies before devices are marketed to vulnerable populations.
References
Primary Study:
Conti, A.A., et al. (2026). “External trigeminal nerve stimulation in youth with ADHD: a randomized, sham-controlled, phase 2b trial.” Nature Medicine. DOI: 10.1038/s41591-025-04075-x.
Medical Disclaimer: This article is for informational purposes only and should not be considered medical advice. Always consult with qualified healthcare professionals before making any health-related decisions or changes to your treatment plan. The information presented here is based on current research and expert opinions, which may evolve as new evidence emerges.
