Associations Between Theory of Mind Impairment, Psychological Flexibility, and Social Functioning during the Remission Phase of Bipolar Disorder

Previous studies indicate that theory of mind (ToM) skills are affected in bipolar disorder (BD). However, findings on the relationship between ToM and social functioning remain inconsistent. This study included forty-one remitted patients with BD and forty-one age and gender-matched healthy controls. In this cross-sectional study, participants completed the Reading the Mind in the Eyes Test (RMET) to assess ToM, the Functioning Assessment Short Test (FAST) to measure social functioning, the Brief Irritability Test (BiTe) for irritability, the Acceptance and Action Questionnaire-II (AAQ-2) for psychological flexibility, and the Valued Living Questionnaire (VLQ) to assess valued living. Hierarchical linear regression and correlation analyses were conducted to determine explanatory variables of social functioning and the role of irritability, psychological flexibility, and valued living. Patients with BD demonstrated lower ToM abilities, psychological flexibility, valued living scores, and higher irritability levels compared to controls. Social functioning was also impaired in the BD group. In healthy controls, ToM performance was associated with social functioning. Psychological flexibility and valued living were correlated with social functioning, indicating that these factors may play a prominent role in functional impairment in BD. While ToM deficits were associated with social functioning in healthy individuals, this relationship was not evident in remitted patients with BD. This suggests other factors, beyond ToM, contribute to social functioning deficits in BD. Further research is needed to clarify these complex relationships.