Theory of Mind Deficits and Their Influence on Functional Impairment in Remitted Phase of Bipolar Disorder

Functional impairment has been convincingly established in the euthymic/ remitted phase of bipolar disorder (BD). Though deficits in social cognition, especially theory of mind (ToM), predict functional impairment, the association has not been consistently proven.

Thirty remitted subjects with BD (as per DSM 5) and 30 age- and gender-matched healthy controls were screened for eligibility and the sociodemographic details and ToM scores, that is, first-order ToM, second-order ToM, and Faux pas, were collected. In subjects with BD, functioning was assessed using Functioning Assessment Short Test (FAST) and illness variables were collected.

No significant difference was found in occupation or education between the groups. Remitted subjects with BD had statistically significant deficits in all domains of ToM, that is, first-order ToM (r = 0.65), second-order ToM (r = 0.69), and Faux pas (r = 0.75). Significant correlations existed between first-order ToM and FAST total score, as well as second-order ToM and FAST total score, but the correlations dropped after controlling for duration of illness and number of depressive episodes. Quantile regression analysis showed that the only factors which predicted global functional impairment was a higher number of episodes (βτ= -0.45, SE = 3.51, t = 0.13, P = 0.04), while all other illness variables and ToM failed to predict the global functioning.

Though there seems to be an association between ToM and functioning, only illness variables predicted functional impairment in subjects with BD. We need prospective studies to delineate the contributors to functional impairment.