Efficacy and safety of transcranial alternating current stimulation in adults with attention deficit hyperactivity...

The transcranial alternating current stimulation (tACS) has been reported to improve attention-related neurophysiological measures in individuals with attention deficit hyperactivity disorder (ADHD); however, robust clinical evidence remains limited. This randomized, double-blind, sham-controlled trial aimed to explore the clinical efficacy, safety, and underlying neural mechanisms of tACS in adults with ADHD. A total of 56 adults with ADHD were randomly assigned in a 1:1 ratio to receive either active tACS or sham stimulation across 20 sessions over four consecutive weeks, with follow-up assessments conducted at week 8 and week 16. Clinical symptoms and resting-state magnetoencephalography (MEG) data were collected before and after the intervention. The tACS group showed significantly greater improvement in inattention symptoms compared to the sham group at week 4, as measured by the Adult ADHD Self-Report Scale - inattention subscale (ASRS-IA) (-10.1 vs. -5.5, p < 0.001, Cohen's d = 1.02). This improvement was sustained at week 8 but attenuated at week 16. Safety profiles were comparable between the two groups. Furthermore, the reduction in ASRS-IA scores was positively correlated with decreased gamma-band connectivity between the orbitofrontal cortex and the precuneus, indicating a desynchronization of neural activity in these brain regions. These findings suggest that tACS may serve as a promising neuromodulation intervention for adult ADHD, demonstrating both clinical benefits and specific neurophysiological mechanisms. TRIAL REGISTRATION: ChiCTR Identifier: ChiCTR2400081121.