Intolerance of Uncertainty Mediates the Relationship between Panic and the Startle Reflex in Anticipation of Unpredictable Threat

Abstract

The present study examined whether intolerance of uncertainty (IU) was associated with the startle reflex in anticipation of unpredictable threat, and whether IU mediated the relationship between panic and sensitivity to unpredictable threat. This was tested in separate samples of 86 undergraduates with varying panic symptoms and 148 adults with current panic disorder or no lifetime history of an anxiety disorder. Participants completed the Intolerance of Uncertainty Scale, which measures cognitive distress (prospective IU) and behavioral inhibition (inhibitory IU) elicited by uncertainty, and a no, predictable, and unpredictable threat-of-shock startle paradigm. In both samples prospective IU was associated with heightened startle during the unpredictable (but not predictable) condition, and in the clinical sample inhibitory IU was associated with attenuated startle during the unpredictable condition. IU mediated the relationship between panic and startle to unpredictable threat. These results support IU as a potential mechanism linking panic and sensitivity to unpredictable threat.