Comparative Study of Cognitive Function Between Treatment-Resistant Depressive Patients and First-Episode Depressive Patients

Objective: Despite reports of cognitive dysfunction during the acute phase of depression, there is a lack of studies in patients with treatment-resistant depression (TRD). The aim of this study was to investigate the cognitive function profile of TRD and compare cognitive dysfunction between subjects with TRD and first-episode depression. Patients and methods: The study included 31 patients with TRD and 53 with first-episode depression. Cognitive function was assessed by a series of neuropsychological tools such as the verbal fluency test, Modified Wisconsin Card Sorting Test (M-WCST), Tower of Hanoi test, Chinese-revision of the Wechsler Adult Intelligence Scale (WAIS-RC), and Trail Making Test A and B. Results: There were no significant demographic differences between the TRD, first-episode depression, and normal control groups (gender, age, years of education). The full-scale, verbal, and performance intelligence quotients measured with the WAIS-RC were also not significantly different (p>0.05). The normal group scores were all significantly better than TRD and first-episode depression, and the TRD group performed significantly worse than subjects with first-episode depression on Trail Making Test B, two WCST subscales, and the profile score of the Tower of Hanoi test (all p<0.05). Conclusion: Patients with depression exhibited global impairments in cognitive function, and these were more common in TRD. Poor executive function may play an important role in TRD.