Cognitive deficits in the euthymic phase of unipolar depression

Although neuropsychological deficits have been reported in patients with major depressive disorder (MDD) during an acute episode, relatively little is known about the persistence of these deficits in remission. This study investigated the performance of attention, executive function and verbal memory during remission from unipolar depressive episodes. We tested the hypothesis that outpatients do not differ in cognitive variables from controls. We did this using a well-defined outpatient sample, consisting of medicated and unmedicated patients, with a history of MDD. Ninety-seven subjects with MDD in remission ranging from young to old were compared with 97 healthy control subjects. Both samples were balanced for age, gender, and education levels. The Auditory Verbal Learning Test (AVLT) and the Trail Making Test (TMT) were used. Patients with remitted MDD, in comparison with controls, were impaired on tasks of attention, executive function and verbal memory. The individual level of depressive symptoms was not related to the cognitive performance. Small- to medium-sized significant correlations exist between cognitive test variables (as represented by Trail Making B and AVLT delayed recall) and level of depressive symptomatology (as measured by MADRS or BDI-II) in the total sample, indicating that higher levels of depressive symptomatology are associated with lower cognitive function. These findings suggest deficits in attention and delayed verbal recall can serve as an indicator for MDD in outpatients.