Abstract
OBJECTIVES: To explore the efficacy and potential neurophysiological mechanisms of 77.5 Hz transcranial alternating current stimulation (tACS) in the treatment of female adolescent non-suicidal self-injury (NSSI). METHODS: Six female NSSI patients received 21 days of 77.5 Hz, 15 mA tACS treatments. Neuropsychological scales were assessed at baseline (W0), after treatment (W3), and 4-week (W7) and 8-week (W11) follow-ups. Transcranial magnetic stimulation with EEG evaluated changes in source-level brain activity and phase-synchronous functional connectivity. Mixed repeated-measures ANOVA with Bonferroni correction (p < 0.017) was used for behavioral data analysis to correct for multiple comparisons. Effect sizes (Cohen's d) was reported for all statistical results. RESULTS: Significant improvements were observed in depressive symptoms and self-injury behaviors after treatment (OSIC: W7: P = 0.009, Cohen's d=-1.682; HAMD-24: W3: P = 0.006, Cohen's d=-1.892; W7: P = 0.001, Cohen's d=-2.839; W11: P = 0.001, Cohen's d=-2.738; all P < 0.017). Electrophysiological analysis revealed that 77.5 Hz tACS might decrease Default network activity, increased Limbic, SalVAttn and Control network activity, and enhanced the functional connectivity in high-gamma band between Control and SalVAttn/Default network. A positive correlation was found between increased C100 activity in the SalVAttn (left frontal-insula) region and reduced HAMD-24 scores (R = 0.826, p = 0.043), this correlation analysis was based on a small sample size (n = 6), and the correlation coefficient was unstable, with results only for preliminary exploratory reference. CONCLUSION: 77.5 Hz tACS may alleviate NSSI symptoms in female adolescents potentially by regulating brain activity and functional connectivity in emotional-control networks.