Ruminations and their correlates in depressive episodes: Between-group comparison in patients with unipolar or bipolar depression and healthy controls

Rumination is an important feature of affective disorders. Relationships between rumination, cognitive function, emotion regulation, and psychological resilience have been examined in unipolar depression; but few studies have determined whether unipolar and bipolar depressive episodes are distinguishable in terms of these variables. This study examined rumination in relation to clinical and cognitive variables in patients with unipolar depression or bipolar depression, and healthy controls. In total, 150 participants (50 bipolar, 50 unipolar, 50 controls) were included. Assessments comprised the Ruminative Response Scale-Short Form, Positive Beliefs about Rumination Scale, Negative Beliefs about Rumination Scale, Brief Resilience Scale, Emotion Regulation Questionnaire, Stroop Test, and Trail Making Test A and B. The unipolar group had significantly higher scores in ruminative response and performed better in a neuropsychological test (Trail Making Test Part A) than the bipolar group. When duration of illness was controlled, no significant difference was found between depression groups in terms of rumination. There was a negative relationship between rumination and emotion regulation (cognitive reappraisal subscale), and rumination and psychological resilience in both patient groups, but no significant relationship was found in healthy controls. Relatively small sample size: future studies in larger clinical samples would increase knowledge of rumination in both unipolar and bipolar depression. Patients experiencing unipolar or bipolar depressive episodes are potentially distinguishable in terms of ruminative response levels and cognitive functions. This differentiation may help in developing targeted interventions for unipolar and bipolar depression.