Selective Serotonin Reuptake Inhibitors and Serotonin and Noradrenaline Reuptake Inhibitors Improve Cognitive Function in Partial Responders Depressed Patients: Results from a Prospective Observational Cohort Study.

Background: Major Depressive disorder (MDD) is often accompanied by cognitive deficits, involving attention, learning, memory and executive functioning. Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin and Noradrenaline Reuptake Inhibitors (SNRIs) show efficacy on affective symptoms, but it is unclear whether or not they improve cognitive symptoms.
Methods: We carried out a 12 week-prospective observational study in two cohorts of recurrent moderate-severe partial responder MDD patients, to test the hypothesis that SSRIs and/or SNRIs may affect cognitive symptoms and assess whether or not such an effect was correlated to their effect on affective symptoms. All patients underwent cognitive and neuropsychiatric assessment at baseline, 4- and 12-week follow-up. Thirty-three patients in the SSRI- and sixteen patients in the SNRI-cohort completed the follow-up.
Results: Both SSRIs and SNRIs reduced affective symptoms and improved global cognitive function. Both SSRIs and SNRIs improved executive function and verbal memory. Global cognitive function, verbal memory and executive function improved both in full and partial responder patients. Finally, there was no correlation between baseline Mini Mental State Examination, Montreal Cognitive Assessment and Frontal Assessment Battery scores and the mean change in Hamilton Psychiatric Rating scale for Depression or Beck Depression Inventory at the end of the 12 weeks of treatment.
Conclusion: Present data show that SSRIs and SNRIs improve cognitive symptoms in MDD independently from their efficacy on affective symptoms. Affective and cognitive symptoms may represent distinct psychopathological dimensions of MDD with different response to antidepressant drugs.