Cognitive deficits in euthymic patients with recurrent depression.

Neurocognitive impairments are found in people recovered from major depression compared with never-depressed controls. A total of 20 patients in recovery from recurrent unipolar depression and 20 healthy controls were tested using a neuropsychological battery containing tasks of executive function (Wisconsin Card Sort Test), attention, visuomotor speed, and working memory. The recovered-depressed group performed poorly in comparison to healthy controls on the planning and problem solving aspects of the Wisconsin Card Sort Test, even after controlling for subclinical depressive symptoms. There was no significant difference between the 2 groups on set-shifting aspects of the task and the other tests. These specific deficits, even after controlling for subclinical depressive symptoms, were correlated with the number of previous episodes of depression. These findings support the hypothesis that impairments in executive function are present in recovery from unipolar depression, and so are not simply state markers. Further longitudinal research on samples free of history of depression is needed to determine whether these impairments are intermediate markers for recurrent unipolar depression, rather than "scars" caused by past episodes.