Theory of mind and executive functions in schizophrenia and bipolar disorder: A cross-diagnostic latent class analysis for identification of neuropsychological subtypes

Abstract

Objective: Executive dysfunction is a common feature of schizophrenia and bipolar disorder (BP). While deficits in social cognitive abilities, including theory of mind (ToM), have been suggested to be specific to schizophrenia, available evidence suggests that there is also a significant overlap in social cognitive performances of both disorders. However, there is significant heterogeneity of executive dysfunction and ToM deficits in BP and schizophrenia. Cross-diagnostic data-driven methods can reveal potential neurocognitive subtypes characterized by relatively selective deficits in social cognition.

Methods: Neurocognitive subgroups were investigated using latent class analysis, based on executive functions and ToM, in a mixed sample of 97 clinically stable patients with schizophrenia or BP and 27 healthy controls.

Results: Four neurocognitive subgroups, including a "neuropsychologically normal" cluster, a severe global impairment cluster and two clusters of mixed cognitive profiles were found. Severe impairment cluster was characterized by particularly severe ToM deficits and predominantly included patients with schizophrenia. Schizophrenia patients in this cluster had severe negative symptoms. In contrast, individuals with BP compared to schizophrenia patients were more likely to be included in the "neuropsychologically normal" cluster.

Conclusion: Identification of distinctive neurobiological subtypes of patients based on social and non-social cognitive profiles can improve classification of major psychoses. Neurocognitive subgroupings of patients might be also beneficial for intervention strategies including cognitive rehabilitation.

Keywords: Bipolar disorder: cognition: heterogeneity; Executive functions; Schizophrenia; Theory of mind.