Neurocognitive performance in melancholic and non-melancholic major depressive disorder: a meta-analysis of comparative studies

Abstract

The aim of this meta-analysis was to investigate differences in cognitive performance between melancholic and non-melancholic major depressive disorder (MDD) during major depressive episodes (MDE) and in remission. We performed a systematic search covering the period from January 1980 to March 2020. The primary outcome was between-groups differences in cognitive domains and subdomains during MDE and after remission. We also meta-analyzed individual tasks and performed sensitivity analyses to test the robustness of our findings. Fourteen studies were included in the MDE analysis and 3 in the remission analysis. During MDE, melancholic underperformed non-melancholic patients in the domains of processing speed and executive functions, and in the subdomains of verbal learning, cued delayed recall/recognition, inhibitory control, and in the global cognitive score. After remission, melancholic patients underperformed their non-melancholic counterparts in verbal fluency. Between-group differences in age and severity were not significant predictors of cognitive outcomes. Our results suggest that, compared with non-melancholic depression, melancholia shows more severe cognitive deficits during MDE and after remission. These data position neurocognitive research as a useful tool for a better characterization of both subtypes of MDD. The scarcity of studies and the high heterogeneity call for the need for future research on this topic.