Deficiency of theory of mind in patients with remitted mood disorder

BACKGROUND: Recent researches on theory of mind (ToM) in patients with mood disorders have revealed deficits of ToM ability during episodes. In this study, we aimed to test ToM ability among patients with unipolar or bipolar depression currently in remission. METHODS: ToM ability and IQ obtained by Wechsler Adult Intelligence Scale-Revised (WAIS-R) were evaluated in 50 patients with remitted depression, who met the criteria of mood disorders of DSM-IV, and 50 matched healthy controls. RESULTS: The patients with mood disorders showed statistically significant impairment in a second-order false question (Fisher's Exact Test p < 0.0001). No significant difference was shown in the other three areas of ToM between the patients and the controls. In addition, no correlation of the four areas of ToM with IQ obtained by WAIS-R was found. LIMITATIONS: The relation of ToM deficit to other specific cognitive impairment was not examined. CONCLUSIONS: Our results suggest that depressive patients in symptomatic remission have a lower ability of second-order false belief. The ToM impairment suggests a decline of skillful social relationships. Evaluation of ToM ability in depressive patients in remission may be useful to provide treatment for better social adjustment.