The impact of neurocognition on mentalizing in euthymic bipolar disorder versus schizophrenia

Introduction: Theory of mind (ToM) or mentalizing deficits have been found in schizophrenia (SZ) and bipolar disorder (BD), but their relationships to patients' coexistent neurocognitive deficits are still unclear. The present study aimed to explore the possible differential involvement of neurocognitive deficits in ToM impairments in SZ and euthymic BD. Methods: Fifty-three euthymic patients with BD type I, 54 clinically stable patients with SZ, and 53 healthy participants were assessed with an advanced ToM task (Faux Pas Recognition Test) which measures cognitive and affective ToM components, and a comprehensive battery of neuropsychological measures. The three groups were matched for gender, age and education. Results: Patients with BD showed significant impairment, comparable to that in SZ, only in the cognitive facet of ToM, whereas SZ patients had significantly poorer performance than both BD patients and healthy participants in overall and affective ToM. In both SZ and euthymic BD, ToM performance was related to deficits in particular cognitive functions. After controlling for coexistent neurocognitive deficits, overall and affective ToM in SZ were still impaired whereas the cognitive ToM impairment in BD and SZ did not remained statistically significant. Conclusions: Our findings suggest a different profile of ToM deficits between SZ and BD and an independence of ToM dysfunction from concurrent neurocognitive deficits in SZ but not in BD.