Anxiety, Fear and Human Defensive Reactions: Behavioural Differentiation of Generalised Anxiety Disorder and Panic Disorder

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In this study we attempt to dissociate, at a behavioural level, the causal mechanisms of fear and anxiety through the use of a translational experimental paradigm, the Joystick Operated Runway Task (JORT). The JORT is the human translation of a rodent task which allows the measurement of the separable behavioural components of simple avoidance (fear) and approach-withdrawal oscillations (anxiety). We have previously developed the JORT and twice validated it pharmacologically, suggesting the task allows the measurement of these two components of human defensive behaviour. Here we would like to apply the task in order to study two clinical conditions, generalised anxiety disorder (GAD) and panic disorder (PD). These disorders are hypothesised to be dissociable from the perspective of defensive behaviour, with GAD involving goal conflict, reflected in increased approach-withdrawal behaviour, and PD involving increased fear, resulting in flight. On the basis of our previous work using the JORT, we surmise that its development from an established animal model has led to a novel and truly translational paradigm that may be useful in the behavioural measurement of human anxiety- and fear-proneness. The task has face validity and we have accumulated evidence of construct validity. Together this evidence suggests that the JORT may tap important variance of the dimensions underlying GAD and PD. However, two important questions remain. First, we need to establish whether anxiety disorder patients, in general, show more intense defensive behaviour than healthy controls. Second we need to determine if the two component processes of the JORT map onto the clinical diagnoses of GAD and PD, as hypothesised. Therefore, in this study we aim to apply the JORT to samples of patients with GAD (N=30), patients with PD (N=30), and healthy controls (N=30). Overall, the proposed research intends to make a significant contribution to our understanding of GAD and PD by dissecting these disorders at the neurobehavioural level using a theoretical framework that maintains that anxiety and fear have functional significance as part of the innate mammalian defensive repertoire.