A meta-analysis of executive dysfunctions in unipolar major depressive disorder without psychotic symptoms and their changes during antidepressant treatment

Objective: Empirical evidence supports the existence of significant executive deficits in patients with major depressive disorder (MDD) as compared to non-depressed controls. Nevertheless, the effect size of executive dysfunctions in unipolar, non-psychotic MDD as well as their relationship to antidepressant treatment is ambiguous. Method: Meta-analytic methods were used to assess the severity of executive dysfunctions in unipolar, non-psychotic MDD as compared to healthy controls and to investigate their course during antidepressant treatment. Results: Fifteen studies comparing the executive functions of 375 patients with DSM-IV MDD and 481 healthy controls were analysed. Furthermore, in three studies, including 122 patients with MDD, the Stroop test performance was examined before and after antidepressant treatment. Patients with MDD performed 0.439 up to 1.18 (P < 0.0001) standard mean differences worse than healthy controls. The Stroop performance improved during the course of treatment (P = 0.0001). Conclusion: We revealed significant executive dysfunctions in patients with unipolar, non-psychotic MDD compared with healthy controls and an improvement of the Stroop performance during the course of treatment. Future studies with different test procedures are needed to further investigate the influence of antidepressant treatment on executive functions.