Theory of Mind and the Association with Psychotic Experiences in 11-Year-Old Children at Familial High-Risk of Schizophrenia or Bipolar Disorder and Population-Based Controls: The Danish High Risk and Resilience Study, VIA 11.

BACKGROUND AND HYPOTHESIS: Theory of mind (ToM) impairments constitute a potential endophenotypic vulnerability marker of schizophrenia and bipolar disorder and have been linked to psychotic experiences. However, studies of ToM in young relatives are sparse, and the association between ToM and psychotic experiences remains understudied in familial high-risk populations. We expected ToM to be impaired in children of parents with schizophrenia or bipolar disorder, and that ToM would be associated with psychotic experiences. STUDY DESIGN: This study is part of The Danish High Risk and Resilience Study-VIA 11, a cohort study of children at familial high-risk of schizophrenia (FHR-SZ, n = 169) or bipolar disorder (FHR-BP, n = 101) and population-based controls (PBC, n = 173). Explicit ToM was measured with the ToM Storybook Frederik and implicit ToM with the Animated Triangles Task. Psychotic experiences were assessed using The Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children - Present and Lifetime Version. STUDY RESULTS: Children at FHR-SZ displayed poorer explicit ToM compared with PBC (P = .002, d = 0.34) and FHR-BP (P = .001, d = 0.42). We found a positive and significant association between psychotic experiences and implicit hyper-mentalizing (P ≤ .006), but not explicit ToM (P ≥ .215). CONCLUSIONS: Children at FHR-SZ show impaired explicit ToM, but future studies should examine potential long-term effects of these impairments. Implicit hyper-mentalizing is associated with perceptual psychotic experiences in childhood, suggesting that this specific ToM deficit may play an important role in the development of psychosis.