Modulation of motor cortical excitability by continuous theta-burst stimulation in adults with autism spectrum disorder

Abstract Objective To test whether change in motor evoked potential (ΔMEP) induced by continuous theta-burst stimulation (cTBS) of motor cortex (M1) distinguishes adults with autism spectrum disorder (ASD) from neurotypicals, and to explore the contribution of two common polymorphisms related to neuroplasticity. Methods 44 adult neurotypical (NT) participants (age 21–65, 34 males) and 19 adults with ASD (age 21–58, 17 males) prospectively underwent M1 cTBS. Their data were combined with previously obtained results from 78 NT and 54 ASD adults. Results ΔMEP at 15 minutes post-cTBS (T15) was a significant predictor of diagnosis (p=0.04) in the present sample (n=63). T15 remained a significant predictor in a larger sample (n=91) and when partially imputed based on T10–T20 from a yet-greater sample (N=133). T15 also remained a significant predictor of diagnosis among brain-derived neurotrophic factor (BDNF) Met+ and apolipoprotein E (APOE) e4– subjects (p’s 0.19). Conclusions ΔMEP at T15 seems to be a significant biomarker for adults with ASD, and its utility is modulated by BDNF and APOE polymorphisms. Significance cTBS response remains a physiologic biomarker for adults with ASD in large samples, and controlling for BDNF and APOE polymorphisms can improve its diagnostic utility.