Are major depression and bipolar disorder neuropsychologically distinct? A meta-analysis of comparative studies.

SAMAMÉ, C.; MARTINO, D.J.; VALERIO, M.P.; SZMULEWICZ, A.G.; STREJILEVICH, S.A.

EUROPEAN PSYCHIATRY

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2017 vol. 39 p. 17 - 26

0924-9338

Background: Neuropsychological deficits are present in both major depression and bipolar disorder. Sofar, however, reports directly comparing these mood disorders with regard to cognitive outcomes havebeen scant and yielded inconsistent results. This work aims to combine the findings of comparativestudies of cognition in major depression and bipolar disorder in order to explore whether theseneuropsychiatric conditions present with distinct cognitive features.Methods: The main online databases were extensively searched to retrieve reports assessingneurocognitive functioning in two groups of mood disorder patients, one with major depressivedisorder and another with bipolar disorder, both in the same phase of illness. Between-group effect sizesfor cognitive variables were obtained from selected studies and pooled by means of meta-analyticprocedures.Results: During euthymia, a significant overall effect size (Hedges?g = 0.64, P < 0.001) favoring majordepressive disorder was found for verbal memory as assessed with list learning tests, whereas nosignificant between-group differences were found for the remaining variables analyzed. Duringdepressive episodes, similar cognitive outcomes were observed between groups.Conclusion: At present, it is not possible to postulate specific neuropsychological profiles for majordepression and bipolar disorder in light of available evidence. It remains to be ascertained whether thedifferences found for verbal memory constitute an expression of distinct underlying mechanisms orwhether they are best explained by sample characteristics or differential exposure to variables with anegative impact on cognition.