Hierarchical affective predictive imbalance in adolescent borderline personality disorder: task-evoked fMRI evidence from multimodal machine learning

Predictive-processing accounts of BPD, including the hierarchical-prior-imbalance account proposed by Herzog, offer a framework for interpreting affective instability and impulsivity. The present task-fMRI study evaluates whether discriminative task-evoked patterns are consistent with this framework; because it does not directly estimate prediction errors, precision weighting, or hierarchical belief updating, it is not a mechanistic test of predictive processing.

To evaluate this question, this study developed a leakage-controlled multimodal machine learning framework for individualized classification of adolescents with BPD and healthy controls based on emotional Go/No-Go task-fMRI activity. Three feature domains were constructed: functional connectivity (FC), task-evoked general linear model (GLM)-derived temporal features, and clinical variables. Seven feature settings, including single-modality, dual-modality, and full multimodal combinations, were evaluated using multiple conventional machine learning classifiers, including logistic regression, support vector machine, k-nearest neighbors, Gaussian naive Bayes, multilayer perceptron, random forest, and XGBoost or gradient boosting.

The results showed that task-evoked GLM-derived features provided the strongest single-modality discriminative information (AUC of 0.881 ± 0.055). SHAP analysis confirmed the predominance of GLM-derived features, accounting for 83.1% of total model attribution, compared to 9.5 and 7.5% for functional connectivity and clinical variables, respectively. At the neural level, discriminative features were distributed across visual/perceptual regions (calcarine, cuneus, occipital cortex), temporoparietal/default-mode hubs (angular and supramarginal gyri), frontal control regions (inferior frontal gyrus), and subcortical structures (putamen). This distributed pattern aligns with a hierarchical organization spanning perceptual input, contextual/self-referential processing, and top-down inhibitory control systems, consistent with the proposed model of hierarchical affective predictive imbalance.

Task-evoked GLM-derived features were the primary source of discriminative information for adolescent BPD, with functional connectivity and clinical variables providing modest additional value. The resulting classification pattern is consistent with hierarchical predictive-processing accounts but does not establish a specific predictive-processing mechanism. The same regional pattern may also reflect visual attention, salience processing, and executive inhibitory control.