Characteristics of theory of mind impairment and its relationship with clinical symptoms and neurocognition in patients with schizophrenia

BACKGROUND: Schizophrenia (SCZ) is a mental disorder that can cause severe disability, including impairment of social cognition, which is considered a core feature of SCZ, and the Theory of Mind (ToM) is a core component of social cognition. Although many studies have confirmed the presence of ToM impairment in patients with SCZ, its characteristics in terms of different orders (first-order and second-order) and components remain unclear, and no studies have investigated the independent correlations between such impairment and clinical symptoms. Therefore, this study aimed to identify the characteristics of ToM impairment in patients with SCZ. METHODS: This study included 30 patients with SCZ and 30 healthy controls who were matched for age, sex, and level of education. The clinical symptoms of the patients with SCZ were evaluated using the Positive and Negative Symptom Scale (PANSS), and the neurocognitive ability of the subjects was evaluated using the Trail Making Test, Symbol Coding Test, and Digit Span Test. The degree of ToM impairment of the subjects at different stages (first- and second-order) and for individual components was evaluated using the Yoni task. Latent profile analysis and network analysis were conducted to identify and analyze the potential ToM performance types, and independent correlations were assessed between ToM impairment and clinical symptoms. RESULTS: The patients with SCZ exhibited significant first-order and second-order impairment (P < 0.05), and the second-order affective ToM component was mainly reflected by complex affective states (P = 0.003). The latent profile analysis revealed that ToM impairments in patients with SCZ could be classified into groups with complete, second-order, and comprehensive defects, whereas it was impossible to classify patients according to differences in the cognitive and affective ToM components. The Network analysis demonstrated that the cognitive component of ToM was associated with positive symptoms, whereas the affective ToM component was associated with negative symptoms. CONCLUSION: Patients with SCZ exhibited differences in order levels and ToM impairments, as well as different defect types. In addition, cognitive and affective ToM components may be related to different psychotic symptoms; therefore, understanding these differences could promote the rehabilitation of patients with SCZ.