Effects of transcranial pulse stimulation on autism spectrum disorder: a double-blind, randomized, sham-controlled trial

Transcranial pulse stimulation has been proven effective to improve cognition, memory and depressive symptoms of Alzheimer's disease, but supporting evidence on other neurological diseases or neuropsychiatric disorders remains limited. This study aimed to investigate the effects of transcranial pulse stimulation on the right temporoparietal junction, which is a key node for social cognition for autism spectrum disorder, and to examine the association between transcranial pulse stimulation and executive and social functions. This double-blinded, randomized, sham-controlled trial included 32 participants (27 males), aged 12-17 years with autism spectrum disorder. All eligible participants were randomized into either the verum or sham transcranial pulse stimulation group, on a 1:1 ratio, based on the Childhood Autism Rating Scale screening score. Sixteen participants received six verum transcranial pulse stimulation sessions (energy level: 0.2-0.25 mJ/mm(2); pulse frequency: 2.5-4.0 Hz, 800 pulse/session) in 2 weeks on alternate days. The remaining 16 participants received sham transcranial pulse stimulation. The primary outcome measure included Childhood Autism Rating Scale score changes, evaluated by parents, from baseline to 3-month follow-ups. Secondary outcomes included a self-reported questionnaire responded to by parents and cognitive tests responded to by participants. A licensed mental health professional evaluated clinical global impression severity, improvement, efficacy and total score. Results revealed significant interactions in Childhood Autism Rating Scale and other secondary outcomes. Significant group and time effects were found in most secondary outcomes. Additionally, significant differences were found between the transcranial pulse stimulation and sham transcranial pulse stimulation groups in Childhood Autism Rating Scale and clinical global impression improvement and total score immediately after 2 weeks of transcranial pulse stimulation intervention (all P < 0.05), and effects were sustainable at 1- and 3-month follow-up, compared with baseline. The effect size of Childhood Autism Rating Scale (d = 0.83-0.95) and clinical global impression improvement (d = 4.12-4.37) were large to medium immediately after intervention and sustained at 1-month post-stimulation; however, the effects were reduced to small at 3-month post-stimulation (d = 2.31). These findings indicated that transcranial pulse stimulation over right temporoparietal junction was effective to reduce the core symptoms of autism spectrum disorder, as evidenced by a 24% reduction in the total Childhood Autism Rating Scale score in the verum transcranial pulse stimulation group. Additionally, the clinical global impression total score was reduced by 53.7% in the verum transcranial pulse stimulation group at a 3-month follow-up, compared with the baseline. Participants in the verum transcranial pulse stimulation group had shown substantial improvement at 1- and 3-month follow-ups, compared with baseline, although some of the neuropsychological test results were deemed statistically insignificant. Future replication of this study should include a larger sample derived from multi-nations to determine transcranial pulse stimulation as an alternative top-on treatment option in neuropsychiatry.