Impaired cognitive control in clinical depression: general but no valence-specific impairments

Introduction: Cognitive control impairments are hypothesized to underlie cognitive and affective features of depression, such as mood-congruent processing biases, rumination, and sustained negative affect. Prior research yielded only mixed evidence for the presence of general cognitive control impairments in depression and the idea of valence-specific reductions in cognitive control has been advocated. To date, the precise role of emotional information in determining the magnitude of cognitive control impairments in task-performing is not fully understood. This study examined reduced internal cognitive control in elation to emotional information and task settings in clinical depression. Methods: Individuals diagnosed with major depressive disorder and matched non/never-depressed control participants (N = 40) performed the Internal Shift Task (IST). This task measures internal cognitive control for both emotional and non-emotional information, here defined as switching between internally held mental representations requiring continuous updating in working memory. Results: Clinically depressed individuals demonstrated general switching impairments. These switching impairments were neither influenced by the task-settings for emotional information (taskrelevant, task-irrelevant) nor by the valence of the stimuli (angry, neutral) in the emotion condition. Moreover, this general switch cost correlated positively with rumination. Discussion: Our findings support the hypothesis that impaired cognitive control is a feature of depression at more severe symptom levels. Interestingly, in the context of prior studies with the IST, the current results suggest that the nature of the cognitive control impairments depend on the depression severity. Whereas clinical symptom levels are associated with an overall reduction, specific relations between cognitive control for emotional information and rumination were observed in subclinical depression. Conclusion: The results of this study provide a better insight in the relation between depression, impaired internal cognitive control and rumination. Future research should examine cognitive control as a vulnerability factor underlying the etiology and maintenance of depression and treatment possibilities (e.g. cognitive control training) could be explored