Local neural synchrony and suicidal ideation severity in adolescents with non-suicidal self-injury

Adolescent non-suicidal self-injury (NSSI) is a strong predictor of suicidal behavior, and there is a need for objective measures that complement the assessment of suicidal ideation severity. This study aimed to examine the association between local neural synchrony and suicidal ideation severity within adolescents with NSSI using resting-state functional MRI (rs-fMRI) and a measure of local neural synchrony (Cohe-ReHo). We recruited 64 adolescent NSSI inpatients, collecting their rs-fMRI data and Beck Scale for Suicide Ideation (BSI) scores. A whole-brain voxel-wise correlation analysis, controlling for sex, age, education duration, head motion, and medication load, was used to explore the relationship between Cohe-ReHo values and BSI scores. To reduce circularity from outcome-based ROI selection, we extracted Cohe-ReHo features from anatomically predefined AAL90 regions and constructed support vector regression (SVR) models for predicting concurrent suicidal ideation severity, with significance assessed via permutation testing and false discovery rate (FDR) correction. The whole-brain analysis identified a significant cluster in the right orbital inferior frontal gyrus (IFGorb), where lower local neural synchrony was associated with greater severity of suicidal ideation. Among all 90 atlas-defined regions, the SVR model based on the right IFGorb demonstrated the highest predictive performance ( R = 0.528, RMSE = 7.109, p FDR = 0.018), significantly predicting individual BSI scores. The right middle frontal gyrus, orbital part, was also identified as a significant predictor ( R = 0.351, p FDR = 0.027). In conclusion, lower local neural synchrony in the right IFGorb was associated with greater suicidal ideation severity among adolescents with NSSI. These findings concern concurrent suicidal ideation severity and do not establish prediction of future suicidal behavior or validate a clinical risk marker.