Experiential, autonomic, and respiratory correlates of CO 2 reactivity in individuals with high and low anxiety sensitivity Jens Blechert a,n , Frank H. Wilhelm a , Alicia E. Meuret b , Eva M. Wilhelm c,d , Walton T. Roth c,d a Department of Psychology, Division of Clinical Psychology, Psychotherapy, and Health Psychology, University of Salzburg, Salzburg, Austria b Department of Psychology, Southern Methodist University, Dallas, TX, USA c Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA d Department of Veterans Affairs Health Care System, Palo Alto, CA, USA article info Article history: Received 11 June 2012 Received in revised form 26 November 2012 Accepted 3 February 2013 Keywords: CO 2 reactivity Heart rate Respiration Anxiety sensitivity Panic disorder Tidal volume Classical conditioning abstract Psychometric studies indicate that anxiety sensitivity (AS) is a risk factor for anxiety disorders such as panic disorder (PD). To better understand the psychophysiological basis of AS and its relation to clinical anxiety, we examined whether high-AS individuals show similarly elevated reactivity to inhalations of carbon dioxide (CO 2 ) as previously reported for PD and social phobia in this task. Healthy individuals with high and low AS were exposed to eight standardized inhalations of 20% CO 2 -enriched air, preceded and followed by inhalations of room air. Anxiety and dyspnea, in addition to autonomic and respiratory responses were measured every 15 s. Throughout the task, high AS participants showed a respiratory pattern of faster, shallower breathing and reduced inhalation of CO 2 indicative of anticipatory or contextual anxiety. In addition, they showed elevated dyspnea responses to the second set of air inhalations accompanied by elevated heart rate, which could be due to sensitization or conditioning. Respiratory abnormalities seem to be common to high AS individuals and PD patients when considering previous findings with this task. Similarly, sensitization or conditioning of anxious and dyspneic symptoms might be common to high AS and clinical anxiety. Respiratory conditionability deserves greater attention in anxiety disorder research. & 2013 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Anxiety sensitivity (AS) refers to a persistent fear of anxiety- related bodily sensations based on the belief that these symptoms have harmful physical, psychological, or social consequences (Reiss, 1991; Smits et al., 2008). Over the last three decades, this personality attribute has given rise to many investigations and is a current focus of considerable attention (reviews in Olatunji and Wolitzky-Taylor, 2009; Naragon-Gainey, 2010). Interest in AS stems from its role as predictor of general psychopathology and particularly of PD. Even though the bulk of research has focused on panic disorder (PD), AS has been found to be relevant to a range of mental disorders. AS measured by the Anxiety Sensitivity Index (ASI, Reiss et al., 1986) is associated cross-sectionally with depression (Rodriguez et al., 2004), posttraumatic stress disorder (Lang et al., 2002; Kilic et al., 2008; Marshall et al., 2010), social and generalized anxiety disorders (e.g., Deacon and Abramowitz, 2006), obsessive compulsive disorder (McWilliams et al., 2007), and several other disorders (Asmundson and Taylor, 1996; Joiner et al., 2008; Olatunji et al., 2009). Longitudinal studies support the role of AS as a precursor of panic attacks and a diagnosis of PD but also of other anxiety disorders (Hayward et al., 2000; Schmidt et al., 2006). It is currently unclear whether there is a specific association between AS and PD over and above AS being a predictor of anxiety disorders or general psychopathology. AS is a cognitive construct concerning beliefs about the harmfulness of somatic symptoms. Several anxiety disorders and PD in particular are characterized not only by high AS, but also by prominent physiological anxiety symptoms, such as breathlessness, racing heart, or sweating (American Psychiatric Association, 1994). Thus, the question arises whether AS mediates a primarily cognitive risk or whether some psychophysiological vulnerability is present in high AS individuals, too. Thus, research on the relationship between AS and PD should profit from measuring precisely both their psychological and physiological aspects. Provoking anxiety in the laboratory would allow the investigator to study this relationship under defined and con- trolled conditions. Recent years have seen an increased interest in the psychophysiological and neuronal correlates of AS among a range of different laboratory conditions (e.g., Killgore et al., 2011; Melzig et al., 2011; McMillan et al., 2012) demonstrating a broad Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/psychres Psychiatry Research 0165-1781/$ - see front matter & 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.psychres.2013.02.010 n Correspondence to: Division of Clinical Psychology, Psychotherapy, and Health Psychology, University of Salzburg, Austria, Hellbrunnerstrasse 34, 5020 Salzburg, Austria. Tel.: þ43 662 8044 5163. E-mail address: jens.blechert@sbg.ac.at (J. Blechert). Please cite this article as: Blechert, J., et al., Experiential, autonomic, and respiratory correlates of CO 2 reactivity in individuals with high and low anxiety sensitivity. Psychiatry Research (2013), http://dx.doi.org/10.1016/j.psychres.2013.02.010i Psychiatry Research ] (]]]]) ]]]–]]]