Depression and rumination: Relation to components of inhibition

Background: Recent research has demonstrated that depressed individuals show impairments in inhibiting irrelevant emotional material, and that these impairments are linked to rumination. Cognitive inhibition, however, is not a unitary construct but consists of several components which operate at different stages of information processing. The present study was designed to assess two components of inhibition and examine their relation to depression and rumination in a sample of clinically depressed and healthy control participants. Methods: Twenty-two individuals diagnosed with a current depressive episode and 27 never-disordered control participants completed an Emotional Flanker Task to assess individual differences in interference control and a modification of the Working Memory Selection Task to assess individual differences in the ability to discard no longer relevant emotional material from working memory. Participants completed self-report measures to assess depressive symptoms and rumination. Results: Clinically depressed compared to control participants showed significantly reduced interference control of irrelevant negative information. The groups, however, did not differ in their ability to discard no longer relevant negative information from working memory. In contrast, rumination was associated with difficulty removing no longer relevant negative material from working memory but not with deficits in interference control. Conclusions: Results highlight the importance of differentiating among components of inhibition to gain a better understanding of cognitive mechanisms underlying depression and rumination.