Transdiagnostic effects of repetitive 10Hz median nerve electrical stimulation on symptom intensity estimates in ADHD, OCD, and generalised anxiety disorder

Previous studies have demonstrated that repetitive trains of low-intensity, 10Hz electrical stimulation of the median nerve (MNS) are effective in reducing tic frequency and the urge-to-tic in individuals with tic disorders such as Tourette syndrome (TS). Converging evidence indicates that TS is highly heritable (50–80%) and shares significant genetic risk with other neuropsychiatric conditions, particularly attention-deficit/hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), and generalised anxiety disorder (GAD), which frequently co-occur with TS. Importantly, it has been proposed that TS and these common comorbidities may reflect overlapping genetic and circuit-level vulnerabilities, rather than independent co-occurring disorders. However, it remains unclear whether non-invasive neuromodulation approaches such as rhythmic MNS, shown to reduce tics and the urge-to-tic in TS, may also be effective in alleviating symptoms across these related conditions. In the present study, 50 participants with moderate to severe symptoms of ADHD, OCD, or GAD (minimum n = 15 per group) underwent pseudorandomised 4-minute blocks of rhythmic 10Hz MNS, arrhythmic MNS, sub-threshold rhythmic 10Hz MNS, and no stimulation. Participants continuously rated the intensity of a pre-identified, disorder-relevant clinical symptom throughout each condition. Results revealed a transdiagnostic effect of MNS, with both rhythmic and sub-threshold rhythmic mu-frequency stimulation producing significant reductions in symptom intensity relative to pre-stimulation baseline levels. These findings suggest that repetitive MNS engages shared neurophysiological mechanisms underlying symptom expression across disorders, highlighting its potential as a scalable, non-invasive intervention for targeting transdiagnostic circuit dysfunction in common neuropsychiatric conditions.