The percentage of cognitive impairment in patients with major depressive disorder over the course of the depression: A longitudinal study

Background: Cognitive impairments (CI) are prevalent and persistent in patients with major depressive disorder (MDD). There is a lack of longitudinal studies exploring the changes of the percentage of CI among MDD patients before and after a long-term antidepressant treatment and the risk factors that predict the residual CI.Methods: A neurocognitive battery was performed to assess four domains of cognitive function, including ex-ecutive function, processing speed, attention, and memory. CI was set as cognitive performance scoring 1.5 SDs lower than the mean scores of healthy controls (HCs). Logistic regression models were conducted to examine the risk factors for the after-treatment residual CI.Results: Over 50 % of patients showed at least one kind of CI. After the antidepressant treatment, the overall cognitive performance among remitted MDD patients was identical to HCs, however, there were still 24 % of the remitted MDD patients had at least one type of CI, especially in executive function and attention. Additionally, the percentage of CI among non-remitted MDD patients was still significantly different from HCs. Our regression analysis further identified that except for the non-remission of MDD, CI at baseline could also predict the residual CI in MDD patients.Limitations: A relatively high drop-out rate at follow-ups.Conclusions: Cognitive impairment in executive function and attention is persistent even in remitted patients with MDD, and baseline cognitive performance can predict the post-treatment cognitive performance. Our findings emphasize the integral role of early cognitive intervention in MDD treatment.