Increased brain glucose metabolism after anodal left DLPFC-right shoulder tDCS in ASD: an open-label pilot F-18 FDG PET/CT study.
BACKGROUND Anodal transcranial direct current stimulation (tDCS) using an extracephalic montage has demonstrated clinical efficacy in improving social functioning in individuals with autism spectrum disorder (ASD), however its neurobiological mechanisms remain poorly understood. METHODS In this open-label pilot study, six adolescents with high-functioning ASD underwent five consecutive daily sessions of 2-mA anodal tDCS, left dorsolateral prefrontal cortex (DLPFC)-right shoulder montage. Therapeutic effects were subsequently assessed by comparing pre- and post-intervention brain glucose metabolism via F-18 FDG PET/CT in 26 regions of interest and clinical symptoms via the Autism Treatment Evaluation Checklist (ATEC) social subscale. RESULTS Following the intervention, metabolic increases exceeding the predefined 10% threshold were observed in four key brain regions: prefrontal lateral, parietal inferior, temporal mesial, and cerebellum (FDR-adjusted p < 0.05). Furthermore, negative correlations were observed between ATEC social scores and metabolic increases in the left prefrontal lateral (r = - 0.832, p = 0.040) and cerebellum (r = - 0.868, p = 0.025). No adverse events were reported. CONCLUSION The metabolic increases were observed after the intervention in key regions, particularly the prefrontal lateral and cerebellum, which correlated with reduced social impairment in adolescents with ASD. These preliminary, exploratory findings warrant evaluation in larger randomized sham-controlled trials. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov Registration (TCTR) on 5 July 2021 (ID: TCTR20210705005; https://trialsearch.who.int/Trial2.aspx?TrialID=TCTR20210705005).