Dimensional subtyping of first-episode drug-naïve major depressive disorder: A multisite resting-state fMRI study.

• A Bayesian model is used to parse depression heterogeneity from both dimensional and categorical prospect. • Three latent factors with distinct but partially overlapping whole-brain hypo- and hyper-resting-state functional connectivity patterns were identified in depression. • The Bayesian model allows an individual to express one or more factors to varying degrees, highlighting the presence of interindividual variability. • The latent factor subgroups captured heterogeneous depression-related RSFC abnormalities more effectively compared to the traditional case-control analysis. Major depressive disorder (MDD) is a heterogeneous syndrome, and understanding its neural mechanisms is crucial for the advancement of personalized medicine. However, conventional subtyping studies often categorize MDD patients into a single subgroup, neglecting the continuous interindividual variations. This implies a pressing need for a dimensional approach. 230 first-episode drug-naïve MDD patients and 395 healthy controls were obtained from 5 sites via the Rest-meta-MDD project. A Bayesian model was used to decompose the resting-state functional connectivity (RSFC) into multiple distinct RSFC patterns (refer to as "factors"), and each individual was allowed to express multiple factors to varying degrees (dimensional subtyping). The associations between demographic and clinical variables with the identified factors were calculated. We identified three latent factors with distinct but partially overlapping hypo- and hyper-RSFC patterns. Most participants co-expressed multiple latent factors. All factors shared abnormal RSFC involving the default mode network and frontoparietal network, but the directionality partially differed across factors. All factors were not significantly associated with demographic and clinical variables. These findings shed light on the interindividual variability in MDD and could form the basis for developing novel therapeutic approaches that capitalize on the heterogeneity of MDD. [ABSTRACT FROM AUTHOR]