Evidence for continuing neuropsychological impairments in depression

Background: Neuropsychological deficits have been reported in patients with major depressive disorder (MDD) during an acute episode of MDD. Little is known whether these abnormalities persist when patients are remitted. The purpose of the present study was to describe the neuropsychological functioning of fully remitted, unmedicated patients with a history of MDD by focusing on tasks related to prefrontal cortex functioning. Methods: Twenty-eight young to middle-aged, unmedicated, fully remitted patients with MDD were compared to 23 healthy control subjects on tasks from the Cambridge Automated Neuropsychological Test Battery (CANTAB) and the California Verbal Learning Test (CVLT). Results: Patients with remitted MDD relative to controls were impaired on tasks of rapid visual information processing (RVIP), psychomotor performance and spatial working memory (SWM). After correction for residual depressive symptoms, deficits in sustained attention remained significant. Limitations: CANTAB tasks are not equated for difficulty, and difficulty differences between the CANTAB tasks and the CVLT are not known. Conclusions: These findings suggest deficits in sustained attention as vulnerability marker for MDD. The functional importance of this finding and the neuronal networks involved remain to be elucidated.