Intolerance of uncertainty fuels depressive symptoms through rumination: Cross-sectional and longitudinal studies.

The current study replicated and extended previous studies by examining the mediating and moderating role of rumination in the relationship between intolerance of uncertainty (IU) and depression in a community sample using both cross-sectional (n = 494; 56.9% female) and a two-months longitudinal (n = 321; 48.4% female) designs. Participants in each study were recruited through online crowdsourcing websites and completed study questionnaires. Results from Study 1 suggested that, while rumination did not appear to moderate the relationship between IU and depression, rumination appeared to partially mediates such relationship. Results from Study 2 supported rumination as fully mediating the relationship between IU and depression over two months. The brooding and reflection rumination subtypes exerted a significant indirect, but not moderating, effect on the relationship between IU and depression. Brooding exhibited a stronger mediation effect than did reflection. Overall, current results suggest that high levels of IU fuel the development of depression symptoms over time through engagement in heightened rumination. The IU-depression association appeared fully explained through rumination as it is a passive and contextually-dependent coping response that may enhance individuals' emotion and facilitate the development of depressive symptoms.