Cognitive heterogeneity and clinical outcomes in adolescent psychiatric inpatients: a data-driven study

Cognitive functioning in clinical settings is typically summarized by the Full-Scale Intelligence Quotient (FSIQ), although increasing evidence suggests that variability across cognitive domains may provide additional clinically relevant information. Cognitive heterogeneity has been associated with functional impairment and psychopathological vulnerability in youth, but most studies rely on single discrepancy metrics rather than multidimensional approaches capable of identifying distinct cognitive configurations. The present study investigated cognitive heterogeneity in an inpatient adolescent psychiatric population using a data-driven approach and examined its associations with adaptive functioning, psychopathological severity, and suicidality. This retrospective observational study included 194 Adolescents aged 12-18 years hospitalized in a tertiary child and adolescent psychiatric inpatient unit. Cognitive functioning was assessed with the Wechsler Intelligence Scales (WISC-IV or WAIS-IV), yielding Verbal Comprehension (VCI), Perceptual Reasoning (PRI), Working Memory (WMI), and Processing Speed (PSI) indices. A unidimensional Discrepancy Index was calculated as the within-subject standard deviation across the four indices and tested for associations with clinical variables. In parallel, Gaussian Mixture Model clustering was applied to identify latent cognitive profiles based on index scores. Clinical and functional outcomes were compared across clusters. The Discrepancy Index showed minimal clinical associations and was significantly related only to non-suicidal self-injury. In contrast, clustering analysis identified four cognitive profiles: high-discrepant, high-harmonic, low-discrepant, and low-harmonic. Cluster membership was significantly associated with adaptive functioning, illness severity, and suicidality. Adolescents with higher cognitive performance demonstrated better adaptive functioning, whereas those with lower cognitive efficiency showed greater illness severity and poorer adaptive skills. Suicidality scores differed across clusters, with the low-harmonic profile showing lower suicidality compared with the high-discrepant group. A multidimensional, profile-based approach captured clinically meaningful cognitive heterogeneity not identified by a single discrepancy index. These findings highlight the relevance of cognitive configuration, beyond global intellectual level, as a potential marker of neurodevelopmental vulnerability and support the use of multidimensional cognitive profiling in the clinical characterization of adolescents with psychiatric disorders. Trial registration: Not applicable.