Theory of mind and neurocognitive functioning in patients with bipolar disorder

Objectives: Studies into social cognition in psychiatric disorders have recently been expanded to address the question of whether or not theory of mind (ToM), i.e., the ability to represent one's own and others' mental states, is impaired in bipolar affective disorder (BPD). Results have been mixed so far, mainly due to possible confounding effects of neurocognition, as well as clinical factors such as acuity and current mood. Here, we explored ToM and its associations with neurocognitive functioning in BPD. Methods: A total of 33 patients with bipolar I disorder (of whom 12 were currently depressed, 10 manic, and 11 remitted) and 29 healthy controls were assessed using a test battery that was identical to the one that was used in previous studies in schizophrenia, comprising diverse neurocognitive tasks, including measures of intelligence, executive functioning, and ToM tasks. Results: The bipolar disorder patient group as a whole and all three clinical subgroups were impaired on all measures of ToM relative to controls, but did not differ from each other in most ToM scores. Patients' poorer performance on executive tasks did not fully explain ToM differences between patients and controls, suggesting a partially selective ToM deficit in BPD. Conclusions: Patients with BPD are impaired in ToM, partially independent of other cognitive dysfunctions and current mood.