Clarifying Fundamental Role of Symbol Coding in Cognitive Networks in Schizophrenia and Healthy Controls Leveraging Gaussian Graphical Models and Bayesian Networks

Abstract

Background and Hypothesis Cognitive impairments in patients with schizophrenia initiate a cascade of effects on daily functioning. A single impairment can affect the functioning of the entire cognitive system. However, the relative interdependence among individual neuropsychological measures—whether the performance of a specific test depends on other tests—remains poorly understood. Study Design The study included a total of 1027 participants (522 patients with schizophrenia and 505 healthy controls) from China. All participants completed the comprehensive 9-test Measurement and Treatment Research to Improve Cognition in Schizophrenia Consensus Cognitive Battery. To examine cognitive relationships, we employed Gaussian Graphical Models for undirected relationships and Bayesian networks for directed relationships among cognitive tests. Study Results Symbol Coding played a central role and exhibited downstream associations with other cognitive tests in both patients and controls. Network analysis showed significant between-group edge differences in undirected networks, particularly between Continuous Performance and Spatial Span (SS), and between Symbol Coding and Managing Emotions (P = .018). A consistent sequential pattern (Symbol Coding → SS → Maze → Trail Making) was identified in both networks. Notably, the Symbol Coding → Managing Emotions connection was uniquely present in the patient’s network. Importantly, Symbol Coding and SS were identified as central variables in schizophrenia, showing extensive connectivity with other cognitive tests. Conclusions Symbol Coding is a fundamental cognitive test in both patients and controls. The association between Symbol Coding and Managing Emotions appears to be a stable feature in schizophrenia. These findings may inform mechanistic insights into cognitive architecture.