The unique and conditional effects of interoceptive exposure in the treatment of anxiety: a functional analysis
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Panic disorder (PD) and claustrophobia are commonly co-occurring anxiety disorders associated with high distress and impairment. Interoceptive exposure (IE; exposure focused on anxiety about somatic sensations) is a well-established component of treatments for PD, but little is known about the specificity of its effects or individual response patterns resulting from this intervention. This study investigated the utility of IE in the treatment of PD with claustrophobia, examining its mechanisms in isolation and in combination with more traditional exposure to phobic situations (situational exposure). Ten adults with PD and claustrophobia (aged 23-74, 30% female) were treated with a flexible single-case experimental approach. Participants received up to 6 sessions of IE exercises (e.g., running in place to build tolerance to racing heart). Nonresponders received up to 6 additional sessions of IE combined with situational exposure entailing entering a closet to induce claustrophobia. Hypotheses included: 1) Reductions in somatic anxiety coinciding with the introduction of IE; 2) Reductions in agoraphobic symptoms coinciding with the introduction of situational exposure for initial nonresponders; 3) Habituation to both interventions whereby distress and participants’ expectancy of the most feared outcome (e.g., fainting) would decrease, and fear tolerance would increase, with improvements maintained at retest. Four participants experienced a clinically significant reduction in somatic anxiety coinciding with IE as predicted; three other participants improved following the addition of situational exposure. One aspect of agoraphobic anxiety – willingness to enter enclosed spaces – generally improved only after combined exposure, as predicted. Both IE and combined exposure elicited habituation whereby distress and expectancies of feared outcomes decreased and fear tolerance increased, supporting hypotheses. All improvements were maintained at retest. Ideographic analysis suggested that IE can rapidly change beliefs about somatic sensations and lead to distress habituation, but has variable immediate effects on overall somatic anxiety and does not reliably reduce related symptom sets (e.g., agoraphobia). IE appeared more helpful to participants who were fearful of the physical consequences of somatic sensations (e.g., heart attack) vs. other consequences (e.g., embarrassment). The observed variability in response to IE and combined exposure suggests a need for individualized implementation of treatments in PD with claustrophobia.