Mediating role of experiential avoidance in the relationship between anxiety sensitivity and eating disorder psychopathology: A clinical replication
Introduction
Eating disorders (EDs) affect millions worldwide and are associated with complex medical comorbidity, increased healthcare costs, decreased quality of life, and elevated risk for mortality (Ágh et al., 2016; Smink, van Hoeken, & Hoek, 2012). Efficacious, evidence-based treatments are available, however a substantial portion of patients treated do not respond favorably (Hay, Bacaltchuk, Stefano, & Kashyap, 2009; Linardon & Wade, 2018). Further, psychiatric comorbidity complicates our understanding of ED psychopathology maintenance, given that the majority of patients presenting for ED treatment have co-occurring depression (estimates range from 24 to 51%; Blinder, Cumella, & Sanathara, 2006; Spindler, 2007; Ulfvebrand, Birgegård, Norring, Högdahl, & von Hausswolff-Juhlin, 2015; Welch et al., 2016) or anxiety disorders (17–55%; Spindler; Strober et al., 2006; Ulfvebrand et al., 2015; Welch et al., 2016). Presence of comorbid psychiatric illness is typically associated with greater ED symptom severity (Kaye, Bulik, Thornton, Barbarich, & Masters, 2004; Spindler, 2007) and poorer treatment outcome (see Vall & Wade, 2015, for review and meta-analysis). Enhancing effectiveness of ED treatments may therefore require targeting maintenance factors for both EDs and comorbid psychopathology.
A growing body of evidence implicates elevated negative affect as a shared vulnerability factor in the development and maintenance of ED psychopathology, anxiety, and depression (Brown, Chorpita, & Barlow, 1998; Craske, 2012; Ellard, Fairholme, Boisseau, Farchione, & Barlow, 2010; Stice, 2002; Wildes & Marcus, 2011). Further, patients with EDs, anxiety, and depression also tend to experience negative emotions at a subjectively higher intensity level (Roemer, Salters, Raffa, & Orsillo, 2005; Svaldi, Griepenstroh, Tuschen-Caffier, & Ehring, 2012) and may be more likely to view these emotions as unacceptable or intolerable than healthy controls (Brockmeyer et al., 2014; Campbell-Sills, Barlow, Brown, & Hofmann, 2006).
Among patients with EDs, anxiety is one dimension of negative affect which serves as a correlate of and precursor to binge eating (Berg et al., 2013; Lavender et al., 2013), vomiting (Berg et al., 2013; Lavender et al., 2013), and dietary restriction (Haynos, Roberto, & Attia, 2015). One potential explanation for this relationship is that anxiety is viewed to have unacceptable negative consequences and therefore is temporarily avoided or suppressed through engagement in ED behaviors (Brockmeyer et al., 2014; Merwin, Zucker, Lacy, & Elliott, 2010; Svaldi et al., 2012). In other words, patients with EDs may be more sensitive to potential negative consequences of anxiety and turn to ED behaviors in orders to avoid such consequences.
The tendency to view the consequences of anxiety as highly aversive is referred to as anxiety sensitivity (Reiss, Peterson, Gursky, & McNally, 1986). This construct was initially conceptualized in the context of anxiety disorders and more specifically refers to intolerance of three components of anxiety—physical sensations, cognitive dyscontrol, and potential for publicly observable signs of distress or social anxiety sensitivity (Reiss et al., 1986). Though most prior research on anxiety sensitivity has focused on anxiety disorders and depression (Naragon-Gainey, 2010; Olatunji & Wolitzky-Taylor, 2009), preliminary research also implicates anxiety sensitivity in disordered eating. An early cross-sectional study involving undergraduate students demonstrated that anxiety sensitivity was positively associated with bulimic symptoms (Anestis, Selby, Fink, & Joiner, 2007). In a community-based sample of adults with overweight or obesity, researchers examined the associations among anxiety sensitivity, eating expectancies, and emotional eating with overweight or obesity (Hearon, Utschig, Smits, Moshier, & Otto, 2013). Results indicated that individuals with higher anxiety sensitivity were more likely to believe that eating leads to a feeling of being out of control. Further, both elevated anxiety sensitivity and the belief that eating leads to a feeling of being out of control interacted to predict greater food consumption after negative mood induction. In a follow-up study using ecological momentary assessment, researchers similarly found that anxiety sensitivity predicted greater caloric intake in response to negative affect (Hearon, Quatromoni, Mascoop, & Otto, 2014). Thus, anxiety sensitivity appears to promote emotional eating in response to negative affect, as well as the sense of loss of control that is characteristic of binge eating in individuals with EDs. However, these studies were all conducted in non-clinical samples and focused primarily on emotional or binge eating. This limits our understanding of anxiety as a maintenance factor in clinically severe ED psychopathology across the spectrum of symptom presentations.
Clinical findings on anxiety sensitivity and eating pathology are sparse, and we are aware of only one study available to date. In a clinical sample of adult outpatients presenting for psychotherapy, researchers found that anxiety sensitivity was positively associated with both drive for thinness and bulimic symptom severity (Anestis, Holm-Denoma, Gordon, Schmidt, & Joiner, 2008). Primary diagnoses for patients in this sample were not reported, so it is unclear how many patients were treated for a clinically severe ED. We are aware of no studies investigating anxiety sensitivity in samples of patients with anorexia nervosa or restrictive EDs. However, research has linked anorexia nervosa with decreased sensitivity and increased emotional reactivity to internal sensations (Berner et al., 2018; Khalsa et al., 2015; Pollatos et al., 2008), as well as greater use of sensory avoidance compared to healthy controls (Zucker et al., 2013). Thus, there is initial evidence that the construct of anxiety sensitivity is relevant across ED diagnoses. Further research in transdiagnostic clinical samples is needed to extend upon these preliminary results.
If the relationship between anxiety sensitivity and ED symptoms is further replicated in clinical samples, an important question remains: through which mechanism does anxiety sensitivity promote ED symptoms? One candidate mechanism is that of experiential avoidance—the tendency to avoid situations or internal experiences that may provoke emotional discomfort (A. Hayes, Wilson, Gifford, Follette, & Strosahl, 1996). Clinically, one might expect that anxiety sensitivity would lead to increased use of ED behaviors as a means of suppressing or distracting from strong emotion. For example, binge eating may serve as a temporary means of distracting from the cognitive and sensory experiences associated with negative emotions (Heatherton & Baumeister, 1991; Manlick, Cochran, & Koon, 2013). Extreme dietary restriction may yield a numbing or dulling of emotional intensity or replace negative emotions with feelings of control (S.C. Hayes & Pankey, 2002; Manlick et al., 2013). Although the ED behaviors that facilitate emotion avoidance may vary, the fear of experiencing distressing emotions may remain consistent across diagnoses.
Although limited data are available in ED samples, research in patients with anxiety and depression suggests that those with greater anxiety sensitivity may overestimate the negative consequences of anxiety and consequently avoid anxiety-provoking situations (Reiss, 1991; Schmidt, Zvolensky, & Maner, 2006). Relief from the avoided perceived negative outcome further reinforces negative expectancies about emotion and maintains these avoidance patterns (Boswell, Anderson, & Anderson, 2015; Reiss, 1991; Schmidt et al., 2006). Empirical evidence supports this theory; experiential avoidance has been found to mediate the relationship between anxiety sensitivity and the presence of social anxiety disorder (Panayiotou, Karekla, & Panayiotou, 2014) as well as severity of depressive symptoms (Stein, Medina, Rosenfield, Otto, & Smits, 2018; Tull & Gratz, 2008) and presence of major depression (Tull & Gratz, 2008).
Although less comprehensive than that for anxiety and depression, a growing body of literature suggests that experiential avoidance is positively associated with ED symptoms (Butryn et al., 2013; Lillis, Hayes, & Levin, 2011; Wildes, Ringham, & Marcus, 2010). In patients receiving residential treatment for EDs, avoidance is positively associated with bulimic symptom severity (Butryn et al., 2013). Among individuals seeking behavioral weight loss treatment, avoidance is positively associated with self-reported frequency of binge eating at baseline (Lillis et al., 2011). It is also positively correlated with global ED symptom severity in transdiagnostic and anorexia-nervosa-only clinical samples (Butryn et al., 2013; Wildes et al., 2010).
We are aware of only one study to date which has examined the extent to which anxiety sensitivity promotes disordered eating specifically through experiential avoidance. Using a nonclinical undergraduate sample, Fulton et al. (2012) examined the cross-sectional relationship between anxiety sensitivity and disordered eating through experiential avoidance. Results demonstrated a positive association between anxiety sensitivity (specifically cognitive concerns) and global ED symptom severity, which functioned through experiential avoidance. Thus, individuals with greater cognitive anxiety sensitivity tended to avoid negative emotions more strongly, and in turn, those with greater avoidance endorsed more severe ED symptoms.
The present investigation sought to replicate the findings from Fulton et al. (2012) in a transdiagnostic clinical sample of treatment-seeking ED patients. We first sought to determine whether the three dimensions of anxiety sensitivity (physical, cognitive, and social) are uniquely and independently associated with ED symptom severity, controlling for comorbid psychopathology. Given that multiple dimensions of anxiety sensitivity have relevance to anxiety and mood disorders (Naragon-Gainey, 2010; Olatunji & Wolitzky-Taylor, 2009), and given shared underlying vulnerability factors for dysregulated response to negative affect (Barlow & Boisseau, 2011; Sloan et al., 2017), we hypothesized that all dimensions of anxiety sensitivity would be associated with greater ED symptom severity. Second, we aimed to determine whether these relationships functioned indirectly through experiential avoidance. We hypothesized that experiential avoidance would act as a mediator of the relationship between anxiety sensitivity and ED symptom severity. Given that patients with EDs commonly experience high rates of comorbidity with anxiety-related and depressive disorders (Blinder et al., 2006; Spindler, 2007; Ulfvebrand et al., 2015; Welch et al., 2016), we also controlled for comorbid symptoms in these domains.
Section snippets
Participants & procedure
Participants were adolescent and adult female patients (N = 625) presenting for ED treatment at one of two private residential facilities in the United States between October 2016 and December 2017. Data were drawn from a de-identified dataset shared by the facility, which includes data from patients with a length of stay >7 days. As a part of treatment, all patients completed computerized clinical intake batteries, typically within three days of admission. Soon after admission, patients were
Clinical participant characteristics
Participants' ages ranged from thirteen to seventy-five (M = 25.11; SD = 10.67). The sample was predominantly White (89%), with the remainder identifying as Black (2%), Asian/Pacific Islander (2%), American Indian/Alaska Native (1%), or other/multiracial (6%). Diagnoses (assigned by patients' treating psychiatrists upon admission) included anorexia nervosa (AN)—restricting type (21%) and anorexia—binge/purge type (22%), bulimia nervosa (BN; 29%), other specified feeding or eating disorder
Discussion
The current study explored whether the positive association between anxiety sensitivity and ED symptom severity observed in non-clinical samples would replicate in a clinical sample, and whether the observed relationship would be mediated by experiential avoidance. In preliminary correlational analyses, all three anxiety sensitivity dimensions were positively associated with ED symptom severity, as was predicted. However, in the regression model including all anxiety sensitivity dimensions and
Strengths and limitations
Study strengths include a large sample size and adequate power to detect significant effects. Further, use of a transdiagnostic sample allows for examination of these constructs across patients with heterogeneous ED symptom presentations, allowing for increased generalizability to a spectrum of symptom profiles. Significant limitations also exist. The cross-sectional nature of this analysis precludes the ability to draw causal conclusions. Confidence in these preliminary results would also be
Conclusion and future directions
The present study provides further evidence that social anxiety sensitivity and experiential avoidance contribute to ED psychopathology, specifically within a clinical ED patient sample. Given the preliminary nature of these findings, replication in outpatient and day hospital samples are warranted to increase confidence in the findings. While beyond the scope of the present analysis, future research may explore whether the relationships observed here vary by ED symptom profile. For example, it
Acknowledgements
The authors wish to thank Shelby Ortiz, Adela Scharff, and Christina Felonis for contributing to database management for this study.
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Present address: Weight Control & Diabetes Research Center, Warren Alpert Medical School of Brown University, 196 Richmond St., Providence, RI 02903, United States of America.