Similar Wires, Different Fires: Reconsidering the Link Between Resting-state Functional Connectivity and Psychopathic Traits

1Psychopathy is a multifaceted construct encompassing affective, interpersonal, behavioural, and antisocial traits. Intrinsic brain organization, captured via functional connectivity, is widely used to map brain-behaviour relationships and to characterize the neural underpinnings of psychopathology. Prior work reports associations between psychopathic traits and altered connectivity in the frontoparietal control, default mode, and salience networks. However, current evidence is constrained by small sample sizes and the reliance on Western, Educated, Industrialized, Rich, and Democratic populations. Therefore, cross-cultural predictive modeling is crucial for identifying robust and generalizable biomarkers linked to psychopathic traits. To address these gaps, we tested whether resting-state functional connectivity (rsFC) predicts psychopathic traits in a non-Western community cohort. Participants (n=97, 52 females, community sample, Japan) completed the Self-Reported Psychopathy Scale-Short Form (SRP-SF) and underwent structural and resting-state functional magnetic resonance imaging. Connectome-based Predictive Modeling (CPM) with cross-validation was applied, and generalizability was evaluated in an independent dataset (n=107, 68 females, community sample, Germany). Across both cohorts, CPM failed to predict psychopathy scores out-of-sample, regardless of model parameters, psychopathic subdimensions, or potential sex differences. Post-hoc analyses indicated, however, that individuals with higher psychopathy scores exhibited more homogeneous rsFC patterns, whereas those with lower scores showed greater variability, suggesting score-dependent heterogeneity in brain-behaviour mapping. These findings highlight key challenges for predictive modeling and point to several future directions, including larger samples, the use of non-linear models, and potentially a shift toward individual-level connectome characterization to better capture heterogeneous neural substrates of similar behavioural phenotypes.