Social cognitive deficits in schizophrenia, bipolar disorder, and first-degree relatives: A large-sample, multi-task investigation

Background: Social cognitive deficits are well documented in schizophrenia (SZ) and bipolar disorder (BD). These deficits extend to first-degree relatives, indicating potential genetic liability. However, most studies have used single tasks with small samples, limiting generalizability. Methods: We examined social cognition across patients with SZ (n = 105), BD with psychotic features (n = 37), first-degree relatives of these patients (n = 101; 60 siblings, 33 parents, 8 offspring), and healthy controls (HC; n = 53). Participants completed four tasks: Penn Emotion Recognition Task (ER-40; facial-emotion recognition), Performance-based Prosody Identification Test (PROID; vocal-emotion recognition), Triangles Task (implicit mentalizing), and Social Attribution Task-Multiple Choice (SAT-MC; explicit mentalizing). We used Bayesian confirmatory factor analysis to derive a social cognition factor and assessed relationships with symptom severity using the Scales for the Assessment of Positive/Negative Symptoms (SAPS/SANS). Results: Groups differed significantly on the social cognition factor (F = 18.10, p < .001), with HC showing highest performance and SZ lowest. BD and relatives showed intermediate deficits, with all pairwise comparisons significant except relatives vs. BD. A group-by-task interaction (F = 3.70, p = .015) revealed larger group differences for mentalizing tasks (SAT-MC, Triangles) than emotion recognition tasks. In patients, social cognition correlated negatively with SAPS (r = -0.217) and SANS (r = -0.255). Conclusions: Social cognitive deficits scale with genetic liability for psychosis, being most pronounced in SZ, intermediate in BD and relatives, and minimal in controls. Deficits are particularly marked for higher-level mentalizing versus emotion recognition, suggesting domain-specific vulnerability. These findings support social cognition as an endophenotype for psychotic disorders with implications for early identification and intervention.