Anorexia nervosa and generalized anxiety disorder: Further explorations of the relation between anxiety and body mass index

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Abstract

We explore comorbidity of anorexia nervosa (AN) and generalized anxiety disorder (GAD) and their relation with body mass index (BMI) and evaluate the presence of fasting and excessive exercise which both have anxiolytic and weight loss effects. All participants were female: 32 with AN only, 607 with GAD only, 22 with AN and GAD (AN + GAD), and 5424 with no history of AN or GAD (referent) from the Swedish Twin study of Adults: Genes and Environment (STAGE). Lowest adult BMI differed significantly (p < .001) and was lower in those with AN + GAD than those with AN only (p < .029). Those with AN + GAD were most likely to endorse fasting and excessive exercise, followed by women with AN only, women with GAD only, and the referent. Comorbid AN and GAD may be a particularly pernicious presentation influencing both BMI and proclivity to engage in behaviors such as fasting and exercise that serve both weight loss and anxiolytic goals.

Highlights

Anorexia nervosa and generalized anxiety disorder are commonly comorbid. ► Individuals with comorbid anorexia nervosa and generalized anxiety disorder may be at increased risk for lower illness-related body mass indices. ► Individuals with comorbid anorexia nervosa and generalized anxiety disorder as well as individuals with generalized anxiety disorder only are more likely to engage in fasting and excessive exercise. ► Comprehensive screening for anxiety disorders in individuals presenting with anorexia nervosa is vital. ► Screening for behaviors such as fasting and excessive exercise in individuals with generalized anxiety disorder may also be warranted.

Section snippets

Participants

Participants for this study were from the Swedish Twin Registry (STR; http://ki.se/twinreg) subsample, the Swedish Twin study of Adults: Genes and Environment (STAGE; http://ki.se/ki/jsp/polopoly.jsp?d=9610&l=en). In 2005, twins aged 20–47 were asked about demographic characteristics, health, and lifestyle habits using web-based surveys with a telephone survey option. The response rate was 59.6%; a detailed description of the study design can be found elsewhere (Furberg et al., 2008,

Results

Of the women included in this study, 5424 comprised the referent group with no history of AN nor GAD [mean (SD) age = 33.9 (7.5)]. Thirty-two women were classified as AN only [mean (SD) age = 34.8 (6.0)], 607 were classified as GAD only [mean (SD) age = 33.3 (7.7)], and 22 women who reported both disorders were classified as AN + GAD [mean (SD) age = 30.1 (6.5)]. Having GAD significantly increased the likelihood of having AN (χ2 = 15.31, p < .001, OR = 6.12, 95% CI = (3.55, 10.54)) and having AN significantly

Discussion

The results of this investigation shed further light on the comorbidty of AN and GAD and extend our understanding of the anxiolytic role that fasting and exercise may play in women with AN and GAD and with GAD only. First, AN and GAD are commonly comorbid with the presence of one substantially and significantly increasing the likelihood of the other. Second, there appears to be a gradient of severity with reference to lowest adult BMI with those individuals with comorbid AN and GAD attaining

Conclusion

The combination of AN and GAD is fairly common and may be a harbinger for increased behaviors that can intensify weight loss associated with AN, such as fasting and exercise, possibly due to anxiolytic effects. These anxiolytic effects may extend to individuals with GAD.

Acknowledgements

This study was supported by grants CA-085739 (P.I.: P.F. Sullivan) and AI-056014 (P.I.: P.F. Sullivan) from the National Institutes of Health. Dr. Dellava was supported by T32MH076694-03 (CMB) and T32MH20030 (PI: Michael C. Neale) and Dr. Root was supported by T32MH076694-03 (CMB) and K01AA018719 (Root). The Swedish Twin Registry is supported by grants from the Swedish Department of Higher Education and the Swedish Research Council. All authors reported no biomedical financial interests or

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