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Original Articles
Introduction
Agoraphobia is characterized as a phobic anxiety in situations where escape can be difficult or embarrassing. Examples of these situations include wide-open spaces, crowded places, shopping malls and public transportation. Patients often anticipate panic attacks or panic-like symptoms, such as a pounding heart or accelerated heart rate, sweating, a feeling of choking, chest pain, dizziness and a fear of dying. Panic disorder and agoraphobia, with a 12-month prevalence of 1.8% and 2%, belong to the most prevalent group of mental disorders - anxiety disorders (Wittchen et al. 2011). More than a third of patients with panic disorder also suffer from agoraphobia (Kessler et al. 2006).
The neural processing of aversive and anxiety-related stimuli relies on the so-called 'fear network' (Gorman et al. 2000). As core regions, the amygdala, hippocampus (Sakai et al. 2005; van den Heuvel et al. 2005) and insula (Nagai et al. 2007; Wittmann et al. 2011) show increased activation in patients with panic disorder with and without agoraphobia. Unfortunately, most previous studies lack information concerning the coincidence of agoraphobia and therefore insights into neural networks specific to agoraphobia are limited (Dresler et al. 2012). Arguably, the neural response of individuals suffering from panic disorder with agoraphobia to the anticipation of, and the confrontation with, agoraphobic situations is equivalent to in vivo exposure. Since in vivo exposure is a first-choice psychotherapeutical intervention for panic disorder with agoraphobia (Gloster et al. 2011), measuring these neural reactions is a highly relevant task. In addition to this, despite the fact that anticipatory anxiety often impairs the daily life of patients to a much greater extent than the anxiety in an agoraphobic situation itself, the anticipatory processes of agoraphobia-related stimuli have not been the focus of large-scale neuroimaging studies. In consequence, the specifically altered activity of the different areas participating in neural processes associated with anticipation and perception of aversive and agoraphobia-related stimuli has not been identified.
Studies investigating the anticipation of aversive and anxiety-related stimuli have found an increased activation in the amygdala, anterior cingulate cortex (Ueda et al. 2003) and the insula (Simmons et al. 2006; Wittmann et al. 2011) as core regions of the neural fear network. (For a more detailed overview of symptom...