A new look at functioning in euthymic bipolar disorder: The role of theory of mind and residual symptoms

Individuals with bipolar I disorder often experience difficulties in social, occupational, and family functioning even following symptom remission (euthymia). The determinants of these deficits remain poorly understood. We investigated the combined and unique contributions of residual symptoms, history of psychosis, cognitive functioning, and Theory of Mind (ToM) to global and domain-specific psychosocial functioning in euthymic patients with bipolar I disorder (EBP).

Global and domain-specific (activities, relationships, self-care, aggressive behaviors) psychosocial functioning, cognitive performance, and ToM were investigated in 110 EBP and 60 matched controls using the Personal and Social Performance (PSP) scale, a neuropsychological battery, and the Faux Pas Recognition Test, respectively. The latter evaluates both general mentalizing abilities and distinct cognitive and affective components. Hierarchical multiple regressions were used to examine the combined and unique contributions of demographic, cognitive, ToM, and clinical predictors of PSP total and domain-specific scores in the patient sample.

The combined predictors in the full/final hierarchical models explained a substantial 44-52 % of variance in each of the Global, Activities, Relationships, and Aggressive Behaviors PSP scores, and a moderate 18 % in Self-care. Residual depressive and subsyndromal non-affective symptoms emerged as the strongest and most consistent predictors, each uniquely explaining 5-18 % of total variance in 3/4 PSP scores. ToM independently explained 10 % of the variance in Global functioning and Relationships. Manic symptoms, cognition, sex, and history of psychosis each uniquely explained 4-10 % of variance in one or two PSP scores.

Targeted interventions addressing subclinical symptoms and social cognition may improve functioning in EBP.