Intolerance of uncertainty, worry, and rumination in major depressive disorder and generalized anxiety disorder.

Intolerance of uncertainty (IU) can be defined as a cognitive bias that affects how a person perceives, interprets, and responds to uncertain situations. Although IU has been reported mainly in literature relating to worry and anxiety symptoms, it may be also important to investigate the relationship between IU, rumination, and depression in a clinical sample. Furthermore, individuals who are intolerant of uncertainty easily experience stress and could cope with stressful situations using repetitive thought such as worry and rumination. Thus, we investigated whether different forms of repetitive thought differentially mediate the relationship between IU and psychological symptoms. Participants included 27 patients with MDD, 28 patients with GAD, and 16 patients with comorbid GAD/MDD. Even though worry, rumination, IU, anxiety, and depressive symptoms correlated substantially with each other, worry partially mediated the relationship between IU and anxiety whereas rumination completely mediated the relationship between IU and depressive symptoms.