Cognitive function in physically healthy, unmedicated individuals with major depression: Relationship with depressive...

We studied cognitive dysfunction in Major Depressive Disorder (MDD) in a sample of healthy, unmedicated individuals without comorbidities. Additionally, we studied the association of cognitive function with response to selective serotonin reuptake inhibitors (SSRIs). Our sample consisted of 113 adult MDD participants and 88 matched healthy controls (HC). Sixty-nine of the MDD participants completed 8 weeks of SSRI treatment. All participants completed a cognitive battery assessing processing speed, executive function, and learning and memory at baseline. This was repeated at week 8 for MDD participants. MDD "Responders" were defined as having ≥50 % improvement on the Hamilton Depression Rating Scale score at week 8 compared to baseline. At baseline, MDD participants performed significantly worse than HC participants on the Symbol Digit Modalities Test (SDMT) (p < .001), Stroop color naming (p = .005) and color-word naming (p = .047), and Brief Visuospatial Memory Test-Revised (BVMT) total recall (p = .02), delayed recall (p < .001), and percent retention (p = .01). MDD participants improved significantly on 6 of the cognitive assessments over 8 weeks. However, there were no significant baseline differences between Responders and Non-responders. SSRI Response was associated with improvement only in the HVLT total recall (p = .02). Our results suggest: 1) a differentiated pattern of cognitive dysfunction exists in healthy, unmedicated MDD compared to HCs; 2) baseline cognition does not delineate an SSRI-responsive/-nonresponsive subgroup, and 3) SSRI response is not associated with broad cognitive improvement after 8 weeks when compared to Non-responders, emphasizing unmet therapeutic challenges.