Executive function profiles identify stable schizophrenia subtypes with distinct symptoms, biological markers and treatment responses: a cross-time clustering and validation study.

BACKGROUND

Executive function (EF) is a heterogeneous neuropsychological construct, and impairments in EF dimensions represent a core aspect of psychopathology in schizophrenia that varies across individual patients. Currently, how this inter-individual variability characterizes schizophrenia subgroups, along with their distinctions in clinical characteristics and prognostic outcomes, remains unclear.

METHODS

Three EF dimensions (inhibitory control, working memory, cognitive flexibility) were assessed in the main sample (N = 329), its follow-up subset, and an independently "recurring local validation" patient sample (N = 114). Fuzzy clustering was applied to baseline EF assessments to discover and validate the core subtypes after excluding cluster-ambiguous cases in the main and independent samples, respectively. Subtype-based classification trained on the main sample was then tested in the independent sample. Importantly, the stability of these subtypes and their remission statuses, along with associated longitudinal changes in clinical and biological factors, were evaluated, and baseline subtype statuses were also used to predict outcomes.

RESULTS

Two longitudinally stable, independently validated core EF subtypes were identified, with Subtype I exhibiting selective deficits limited to response inhibition and cognitive flexibility ("EF-Focal") and Subtype II showing broad EF impairments across all dimensions ("EF-Global"). Compared to the "EF-Global" subtype, patients within the "EF-Focal" subtype presented significantly milder positive, affective, and cognitive symptoms, worse working memory updating, lower inflammatory markers, and better metabolic profiles at baseline. Models trained on baseline EF assessments from the main sample accurately classified patient subtypes in the independent sample (area under the curve [AUC] = 0.79); these baseline subtypes moreover classified patients' remission statuses independently of overall severity at intake (AUC = 0.78). Remitted patients were observed to have significantly greater reductions in negative and cognitive symptoms, improved working memory maintenance, lower peripheral inflammatory levels, and superior metabolic functions over time.

CONCLUSIONS

EF subtyping was associated with symptomatic, biochemical, and prognostic variations in individuals with schizophrenia, which could help to stratify patients within this disorder for targeted treatments.