A reappraisal of the intertwined association between affective lability and mood reactivity in a post hoc analysis of the BRIDGE-II-MIX study

Objective: This post hoc analysis of the BRIDGE-II-MIX study is aimed at evaluating affective lability (AL) as a possible clinical feature of mixed depression and assessing the relationship with atypical depressive features, particularly mood reactivity (MR). Methods: In the BRIDGE-II-MIX multicenter, cross-sectional study, 2,811 individuals suffering from a major depressive episode (MDE; DSM-IV-TR criteria), in the context of bipolar I or II disorder (BD-I, BD-II, respectively) or major depressive disorder, were enrolled between June 2009 and July 2010. Patients with (MDE-AL, n = 694) and without (MDE-noAL, n = 1,883) AL and with (MDE-MR, n = 1,035) or without (MDE-noMR, n = 1,542) MR were compared through χ2 test or Student t test. Stepwise backward logistic regression models, respectively testing AL and MR as the dependent variable, were performed to differentiate the 2 clinical constructs. Results: AL was positively associated with BD-I (P < .001) and BD-II (P < .001), with DSM-5 mixed (DSM-5-MXS) (P < .001) and atypical (DSM-5-AD) features (P < .001) and negatively associated with MDD (P < .001). In the logistic regression models, MR was the variable most significantly associated with AL and vice versa (P < .001 for both). AL was positively associated with severity of mania and DSM-5-MXS and negatively correlated with severity of depression, while MR was better predicted by atypical symptoms such as hyperphagia, hypersomnia, and leaden paralysis and correlated with both comorbid anxiety disorders and DSM-5-MXS. Conclusions: Mixed and atypical depression may lie on the same continuum. MR and AL could represent the underlying matrix, bridging the gap between mixed and atypical depression.