Diagnostic utility of worry and rumination: a comparison between generalized anxiety disorder and major depressive disorder.

Aim: Although previous reports have addressed worry and rumination as prominent cognitive processes in generalized anxiety disorder (GAD) and major depressive disorder (MDD) and their distinct correlation with anxious and depressive symptoms, the differential association of worry and rumination with the diagnosis of GAD and MDD remains unclear. The purpose of this study was to investigate the distinct features of worry and rumination in factor structure and their predictive validity for the diagnosis of GAD and MDD.

Methods: Four hundred and sixty-eight patients with GAD (n = 148) and MDD (n = 320) were enrolled and the diagnoses were confirmed with the Structured Clinical Interview for DSM-IV. Participants completed the Penn State Worry Questionnaire and Ruminative Response Scale and the severity of anxiety and depressive symptoms was assessed via clinician ratings.

Results: In joint factor analysis using the Penn State Worry Questionnaire and Ruminative Response Scale items, worry and rumination emerged as distinct factors. In logistic regression analyses, worry contributed to a higher probability of the diagnosis of GAD than rumination, as rumination did in MDD than worry.

Conclusion: This is the first comprehensive study investigating the diagnostic utility of worry and rumination in a well-defined clinical sample of both GAD and MDD. Our results suggest that worry and rumination are distinct cognitive processes and play a differential role in the diagnosis of GAD and MDD, distinguishing them at the cognitive level.