Responding to uncertain threat as a potential mediator of an inverse relation between mindfulness and anxiety

Background and objectives: The benefits of applying mindfulness-based interventions to the treatment of anxiety have gained extensive support. However, mechanisms for this relation remain largely unexplored. Emotional reactivity to uncertainty plays a central role in anxiety and may represent a mechanism of interest, as mindfulness meditation fosters an open and accepting attitude towards all (including aversive) experience. The present study investigated the potential mediating role of emotional reactivity to uncertainty using (a) a self-report measure of intolerance of uncertainty (IU) and (b) startle reflex and self-rated anxiety in response to an uncertainty manipulation in a conditioning task.Methods: In a cross-sectional design, 53 undergraduate students completed a number of self-report questionnaires assessing generalized anxiety, obsessive-compulsive, panic, and social anxiety symptoms, as well as measures of mindfulness and IU. Furthermore, participants completed the NPU-threat test, a threat-of-shock paradigm that consists of (1) a no-shock condition, (2) a predictable condition in which shock is reliably predicted by a cue, and (3) an unpredictable condition in which shock is not paired with a reliable predictor. Aversive responding throughout the different conditions is measured with the startle reflex by delivering startle probes during both cues and intervals between cues. Further, self-report is used to assess subjective anxiety in response to thethree conditions.Results: The self-report measure of IU was found to mediate the relation between trait mindfulness and (I) generalized anxiety symptoms and (II) obsessive-compulsive symptoms. The startle responses and anxiety ratings from the NPU-threat test were found to be largely unrelated to mindfulness, anxiety symptoms, and self-reported IU.Discussion and conclusion: The results provide initial evidence that emotional reactivity to uncertainty may play a role in the relationship between mindfulness and some types of anxiety. The findings concerning self-reported IU suggest that future research efforts should explore its mediating role in larger samples to minimize possible power problems due to collinearity between predictors. Furthermore, the results also highlight potential limitations of using a conditioning task to manipulate uncertainty-related anxiety in a student sample, including that the uncertainty manipulation may lack ecological validity. Other potential implications and future directions for research are discussed