Preliminary evidence concerning the pattern and magnitude of cognitive dysfunction in major depressive disorder using cogstate measures.

BACKGROUND: Cognitive deficits are common in individuals with major depressive disorder (MDD), and are associated with treatment non-responsiveness and poorer functional outcomes. Characterization of the nature and magnitude of deficits in this population has been limited in part by lack of brief, practical, and well-validated assessment measures. The goal of this study was to use a brief, practical, and repeatable computerized cognitive test battery from Cogstate to examine differences in cognitive functioning between individuals with MDD and healthy controls.

METHODS: Forty participants (22 healthy controls (HCs), 18 with MDD) completed a battery of six cognitive measures, as well as measures of intellectual functioning (intellect) and depressive symptom severity. A multivariate analysis of covariance (MANCOVA) was conducted to compare cognitive test performance across groups while controlling for intellect.

RESULTS: Individuals with MDD had lower full-scale IQ scores on average, and performed worse on measures of visual attention (d=1.04), verbal learning (d=1.22) and memory (d=1.22), and visuospatial problem solving (d=0.80) than HCs after adjustment for differences in intellect. Psychomotor speed, visual memory, and working memory did not differ between groups.

CONCLUSIONS: Cogstate measures appear to be sensitive in assessing deficits in attention, verbal learning and memory, and executive function in individuals with MDD. Further research will be useful in establishing the utility of Cogstate measures for standard use in research and clinical practice.