Less inhibited and more depressed? The puzzling association between mood, inhibitory control and depressive symptoms

Background: Inhibitory control (IC) deficits have been proposed as a potential risk factor for depression. However, little is known about the intra-individual daily fluctuations in IC, and its relationship to mood and depressive symptoms. Here, we examined the everyday association between IC and mood, in typical adults with various levels of depressive symptoms. Methods: Participants (N = 106) reported their depressive symptoms and completed a Go-NoGo (GNG) task measuring IC at baseline. Then, they completed a 5-day ecological-momentary-assessment (EMA) protocol, in which they reported their current mood and performed a shortened GNG task twice/day using a mobile app. Depressive symptoms were measured again following the EMA. Hierarchical-linear-modeling (HLM) was applied to examine the association between momentary IC and mood, with post-EMA depressive symptoms as a moderator. Results: Individuals with elevated depressive symptoms demonstrated worse and more variable IC performance over the EMA. In addition, post-EMA depressive symptoms moderated the association between momentary IC and daily mood, such that reduced IC was associated with more negative mood only for those with lower, but not higher, symptoms. Limitations: Future investigations should examine the validity of these outcomes in clinical samples, including patients with Major Depressive Disorder. Conclusions: Variable, rather than mere reduced, IC, is related to depressive symptoms. Moreover, the role of IC in modulating mood may differ in non-depressed individuals and individuals with sub-clinical depression. These findings contribute to our understanding of IC and mood in real life and help account for some of the discrepant findings related to cognitive control models of depression.