Threat appraisal and negative affect under ambiguity in generalised anxiety disorder.

Generalised anxiety disorder (GAD) is one of the most common anxiety disorders, yet its mechanisms remain poorly understood. In the current study, we assessed threat processing and negative affect under conditions of uncertainty and ambiguity in a sample of treatment-seeking individuals with GAD (n = 34) and in community controls (n = 34). Participants completed a laboratory aversive learning task based on that used by Grupe and Nitschke (2011). A bias in threat expectancy was observed in GAD participants relative to controls for an ambiguous cue that had not been mentioned in the instructions. GAD participants also overestimated the number of times this ambiguous cue had been followed by an aversive outcome, relative to an instructed uncertain cue (50 %). This covariation bias was not observed in controls. GAD participants also reported significantly stronger negative affect towards the ambiguous cue than the uncertain cue, a pattern that was not observed in controls, although the group interaction did not reach significance. These results provide preliminary evidence that ambiguity - rather than uncertainty per se - may be a particularly powerful trigger for biased threat appraisal and negative affect in GAD.