Cognitive Impairments in Unipolar Depression: The Impact of Rumination

Major depressive disorder (MDD) is associated with impairments in several cognitive domains. People with depression also tend to focus on and think about their problems ("ruminate") more than people without depression. Recent studies indicate that depressive rumination is connected to cognitive impairments in MDD. However, there is little scientific understanding of the role of rumination in these deficits.

The current study examined the performance of 62 outpatients suffering from unipolar major depression with a low tendency to ruminate versus outpatients with a high tendency to ruminate using a neuropsychological battery covering the 5 cognitive domains: attention, memory, working memory, executive functions and processing speed.

The results indicated that high ruminators show a lower performance than low ruminators with regard to processing speed and executive function tasks with low effect sizes. However, these findings were not significant after Bonferroni correction. Hierarchical linear regression revealed that the effect on processing speed could be partially attributed to rumination, but an effect on executive functions was not established.

The current study is the first to systematically investigate the impact of rumination on cognitive impairments in MDD, exploring a broad range of cognitive domains. The results partially support the hypothesis that rumination has an impact on single cognitive domains and highlight the necessity for further investigations in order to generalize these findings.