Maladaptive metacognitive beliefs mediated the effect of intolerance of uncertainty on depression.

Both elevated intolerance of uncertainty (IU) and maladaptive metacognitive beliefs (MBs) were associated with depression. However, the relationship between MBs and IU in clinical depression is unclear. The current study aimed to investigate the putative impairment of MBs and IU in major depressive disorder (MDD) and explore the relationship between these two factors with depressive symptoms. Metacognition Questionnaire-30 Items (MCQ-30), Intolerance of Uncertainty Scale-Short Form (IUS-12) and clinical rating scales were administered to 53 patients with MDD and 56 healthy controls (HCs). Stepwise regressions were performed to explore independent contributions of MBs and IU on depression. Mediation analysis was used to examine associations among variables. Patients with MDD reported higher IUS-12 and MCQ-30 scores than HCs. Stepwise regressions revealed a unique contribution of negative MBs concerning the consequences of not controlling thoughts (MCQ-NC) on depression symptoms while controlling the effects of age, gender, anxiety symptoms and IU. MCQ-NC and negative MBs concerning the uncontrollability and danger of negative thinking (MCQ-NEG) completely mediated the effects of IU on depression and anxiety symptoms. Our results provided clear evidence that maladaptive negative MBs are directly associated with depression symptoms, and mediated the effect of IU on depression and anxiety symptoms, suggesting that IU and MBs influence clinical symptoms in a hierarchical manner.