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Preliminary Results of Therapeutic Potential of Multiple Sessional Intermittent Theta Burst Stimulation over the Bilateral Posterior Superior Temporal Sulci in Children and Adolescents with Autism Spectrum Disorder
Accumulating studies have demonstrated the therapeutic potential of the repetitive trans-cranial magnetic stimulation (rTMS) on improving the core symptoms of autism spectrum disorder (ASD). However, the accurate and consistent stimulation targets and protocols remained elusive.
The posterior superior temporal sulcus (pSTS) is an important brain region for the social brain network and theory of mind. Further, several studies have demonstrated the abnormal activation of pSTS in ASD. Therefore, pSTS may serve as another potential therapeutic target of rTMS in ASD.
Theta-burst stimulation (TBS) is a modified rTMS and is capable of producing excitatory or inhibitory aftereffects on cortical excitability as traditional rTMS. Moreover, TBS is more advantageous than the traditional TMS in being more efficient to produce the similar after-effects in a much shorter duration with fewer total stimulus pulses at lower stimulus intensity. TBS is considered more implementable in the clinical practice.
Objectives:
The aim of this study is to investigate the therapeutic impacts of intermittent TBS (iTBS) to the bilateral posterior superior temporal sulci (pSTS) in children and adolescents with ASD.
Methods:
The study was implemented as an randomized, double-blinded, sham-controlled and parallel trial. 80 children and adolescents with ASD were randomly assigned to the pSTS or sham-control group. In phase 1, the participants received either iTBS or sham stimulations twice per week for 4 weeks. In phase 2, after completing the first 4-week interventions in phase 1, all of the participants were invited to receive real iTBS twice per week for another 4 weeks. After completing phase 2, all of the participants will be followed up 4 weeks later. We measured the clinical symptoms and neuropsychological functions at baseline, at 4 weeks (post 4w, phase 1), 8weeks (post 8w, phase 2) and 12weeks (post 12w, follow-up). The clinical symptoms were measured with the Autism Spectrum Quotient (AQ), the Social Responsiveness Scale (SRS) and the Repetitive Behavior Scale-Revised (RBS-R) as rated by parents, respectively. The neuropsychological functions were assessed with the Frith-Happe animations and Eye tasks.
Results:
Hitherto, there were 74 participants enrolled in the trial. 5 participants were excluded from this study because of personal reasons (n=2), somatic discomforts (dizziness and insomnia, n=2) and abnormal MRI findings (brain tumor, n=1). Overall, the preliminary analyses showed trend-level decreases in total scores of the AQ, SRS and RBS-R at post 4w and post 8w in the pSTS group. The improvement was more obvious in post 8w than post 4w and persisted at post 12w. Among the clinical symptoms, the improvement in the social communication domain was most obvious. Preliminary analysis revealed that the improvement was not associated or mediated by intelligence, gender or age. As for the results in the neuropsychological functions, the interpretation of social intention during the Frith-Happe animations task improved in the pSTS group at post 4w.
Conclusions:
Our preliminary results suggest that the bilateral pSTS may be a potential therapeutic target of rTMS in ASD, especially for improvement in social function. Besides, the therapeutic effects may be more prominent with longer duration of interventions.