Multiplex Community Detection for Subgroup Identification within Functional Connectivity Networks

Identifying homogeneous subgroups with similar symptoms or neuropsychological patterns is essential for understanding the heterogeneity of psychotic disorders and advancing precision medicine, which enables tailored treatments based on patients' unique profiles. Existing data-driven methods, such as independent component analysis or independent vector analysis (ICA/IVA) applied to multi-subject functional magnetic resonance imaging (fMRI) data, have successfully revealed meaningful subgroups. However, these methods often rely on single-dimensional information, such as isolated functional networks, or assume uniform subgroup structures across all networks. Given the complexity of psychiatric disorders, exploring relationships across multiple functional networks can provide deeper insights into diagnostic heterogeneity. To address this, we propose a novel method that integrates cross-functional network information for subgroup identification by constructing multiplex networks from functional connectivity networks extracted from multi-subject resting-state fMRI data. Multiplex network-based community detection is then applied to identify both common communities spanning multiple networks and private communities specific to individual networks. Results from simulations and real-world fMRI data demonstrate the effectiveness of the proposed method. In a study of 464 psychotic patients, the identified subgroups exhibit significant differences in key functional areas, such as the default mode network (DMN) and anterior prefrontal cortex (antPFC), as well as corresponding clinical scores. These findings align with prior clinical studies, demonstrating the ability of the proposed approach to uncover clinically relevant subgroups and enhance understanding of psychotic disorder heterogeneity. By considering multi-dimensional information across functional networks, this approach provides a framework for understanding individual variability in psychotic disorders and paves the way for precision medicine.