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Kimberly Pulse

The Comorbidity of Anxiety Disorders
and Eating Disorders

Table of Contents
I.  Introduction
II. Definitions of the Eating Disorders and Anxiety
III. Case Studies
IV.  Scientific Research Studies
V.  Conclusions
VI. References

I. Introduction

Considering the growing preoccupation of teenage girls with their weight and their bodies, eating disorders have become even more of a concern.  In light of the fact that mortality in anorexia nervosa is among the highest of all psychiatric disorders, it is increasingly important to understand what causes eating disorders and how best to treat them (Herzog et al., 1996).  A meaningful area of research to consider when trying to understand eating disorders is comorbidity.  Such psychiatric disorders such as anxiety disorders, affective disorders, personality disorders, and substance abuse have been found to coexist, at least to some degree, with the eating disorders anorexia nervosa and bulimia nervosa.  This paper will examine how anxiety disorders have been found to interact with both anorexia nervosa and bulimia nervosa.

II.  Definitions of the Eating Disorders and Anxiety

The DSM-IV outlines four criteria for anorexia nervosa (APA, 1994).  One, a refusal to maintain body weight over a minimal normal weight for age and height (i.e., weight loss leading to maintenance of body weight less than 85% of that expected).   Two, an intense fear of gaining weight or becoming fat, even though underweight.  Three, a disturbance in the way in which oneís body weight, size, or shape is experienced (i.e., denial of the seriousness of current low body weight, or undue influence of body shape and weight on self-evaluation).  Four, in post-menarcheal, amenorrhea (the absence of at least three consecutive menstrual cycles).  Two types of anorexia nervosa are defined.  The binge eating/purging subtype means that the individual engages in recurrent episodes of binge eating or purging during the episodes of anorexia nervosa.  The restricting subtype means that the person does not engage in binge eating or purging during the episodes of anorexia nervosa.

The DSM-IV outlines five criteria for bulimia nervosa (APA, 1994).  One, there are recurrent episodes of binge eating.  Binge eating is defined as eating in a discrete period of time an amount of food that is definitely larger that most people would consume in a similar period of time.  The binge eating must also be characterized by a sense of lack of control over eating.  Two, there are recurrent inappropriate compensatory behaviors in order to prevent weight gain such as self-induced vomiting, the misuse of laxatives or diuretics, fasting, or excessive exercise.  Three, the binge eating and inappropriate compensatory behavior both occur, on average, at least twice a week for three months. Four, self-evaluation is unduly influenced by body shape and weight.  Five, the disturbance does not occur exclusively during episodes of anorexia nervosa.  There are two types of bulimia nervosa:  the purging type (the person regularly engages in self-induced vomiting or the misuse of laxatives or diuretics) and the nonpurging type (the person uses other compensatory strategies such as fasting or excessive exercise).

Anxiety is defined as ďa mood state characterized by marked negative affect and somatic symptoms of tension in which a person apprehensively anticipates future danger or misfortuneĒ (Durand & Barlow, 1997).  There are many disorders which fall under the heading anxiety disorders.  Generalized anxiety disorder is characterized by intense, uncontrollable, unfocused, chronic, and continuous worry that is distressing and unproductive, accompanied by physical symptoms of tenseness, irritability, and restlessness (Durand & Barlow, 1997).  Panic attacks are abrupt experiences of intense fear and discomfort accompanied by a number of physical symptoms such as dizziness (Durand & Barlow, 1997).  Panic attacks can occur with and without agoraphobia, which is anxiety about being in certain places or situations.  Specific phobias are irrational fears of specific objects or situations that interfere with everyday functioning (Durand & Barlow, 1997).  For example, some people have phobias about spiders or elevators.  A social phobia is long-lasting irrational fear of social or performance situations that is so extreme that the person will go to great lengths to avoid those situations (Durand & Barlow, 1997).  Posttraumatic stress disorder (PTSD) are emotional disorders that occur after traumatic events such as physical assault, rape, and auto accidents.  The victim often becomes numb and remains increasingly distressed, particularly when exposed to any reminders of the traumatic event.  (Durand & Barlow, 1997).  Finally,  obsessive-compulsive disorder involves unwanted, persistent, intrusive thoughts that require repetitive actions to suppress them (Durand & Barlow, 1997).

These six anxiety disorders defined above have all been examined in research studies aimed at determining the comorbidity of anxiety and eating disorders.  However, some have been found to play a great role than others.  Social phobia, obsessive-compulsive disorder, and specific phobias have the highest rates of co-occurrence with bulimia nervosa, while social phobia and obsessive-compulsive disorder have the highest rates of co-occurrence with anorexia nervosa (Wonderlich & Mitchell, 1997).  The anxiety disorders which have been found to occur most often with eating disorders will be the ones focused on within this paper.

III. Case Studies

Betty E. Chesler, a therapist in private practice, provides one case study examining the relationships between panic and eating disorders and four case studies examining the impact of stress, fear of fatness, and panic disorder with agoraphobia on eating disorders. All of the case studies explore the interactions between an anxiety disorder, in this case panic disorders, and an eating disorder.

Cheslerís first case study describes how stress, fear of fatness, and panic disorder with agoraphobia combined to change an individualís eating disorder from bulimia to food restriction (Chesler, 1995).  Gema, a 37-year old housewife, had suffered from all of the eating disorders for many years.  She began dieting and restricting food from an early age,  and by age 33 she was bingeing and vomiting about three times a week.  When Gema was 35, she was diagnosed with panic disorder with agoraphobia.  At this point, her bulimia  ceased, and she began restricting her food intake.  She began experiencing panic attacks at the same time that her marriage began failing.  She began dieting because she believed that  her weight was the reason for her marital discord.  Not only did she develop a fear of choking, but the panic became so intense that she eventually could not even leave her  home.  She began to believe that eating caused her panic, and therefore she restricted her  food intake even more.  Avoiding eating created an illusion of control for Gema.

For Chesler, the importance of Gemaís case is that if a person presents with a panic disorder which involved difficulty swallowing or a fear of choking, that person should be  evaluated for an eating disorder.  It may be that the patient needs to be treated  simultaneously for an eating disorder and an anxiety disorder. The other four cases which Chesler examined involved eating-disordered patients who  attempted to alleviate panic with food and as a result worsened both the panic and eating  disorder symptomatology (Chesler, 1997).  When these patients would feel panicky  feelings, they would binge eat in an attempt to lessen the panic.  Consequently, the  bingeing would trigger fears of fatness which led to more panic which led to purging behaviors and/or dieting.  Similar to the above study, the implications of these for case studies for Chesler are that patients diagnosed with both a panic disorder and an eating disorder should be evaluated  to see whether or not he or she is using food as a coping strategy.  If so, that person will  need to be treated for both panic and eating disorders at the same time. Although, case studies are not as reliable as controlled research studies, they can still be of  usefulness, even if limited.  These five case studies point to the fact that a relationship between anxiety disorders (in these instances, specifically panic disorder) and eating disorders does exist.  The importance of Cheslerís research is that it demonstrates how the  co-occurrence of anxiety and eating disorders can serve to worsen the symptomatology of  each disorder.  In other words, the two disorders can influence one another in extremely  negatively reinforcing ways.  Obviously, more carefully controlled studies involving large  samples should be conducted to see if other researchers uncover Cheslerís findings.


IV.  Scientific Research Studies

In fact, controlled research studies with large samples have been done which point to a relationship between anxiety and eating disorders, although Cheslerís specific results were not touched upon in any of the studies examined here.  What these research studies have found, however, is that anxiety disorders occur frequently with eating disorders and that in  the majority of cases, the onset of the anxiety disorder preceded the onset of the eating disorder.

Brewerton et al., 1995
Brewerton et al. looked specifically at the comorbidity of axis I psychiatric disorders (as defined in the DSM-IV) and bulimia nervosa (Brewerton et al., 1995).  The Structured  Clinical Interview for DSM-III-R was given to a sample of 59 female patients with  DSM-III-R defined bulimia nervosa.  Patients were required to have binged at least three times per week for six months.  This study found higher than expected frequencies of anxiety disorders (36%), especially social phobia (17%).  Five of the ten patients with social phobia had another anxiety disorder as well:  three had generalized anxiety disorder, two had panic disorder, and one had a simple phobia.  Of the 21 (36 %) of the 59 patients with any anxiety disorder, 15 (71%) of 21 cases had the onset of their anxiety disorder prior to the onset of their eating disorder.  In 4 of the 21 cases (19%) the eating disorder came first.  In 2 (10%) of the 21 cases, the onset of the eating disorder occurred within the same year as the onset of the anxiety disorder.

The potential importance of these findings are that if the results are able to be generalized to the rest of the population, bulimics are likely to be suffering from a comorbid affective or anxiety disorder.  It is possible that if either the affective or anxiety disorder were treated, that the bingeing and purging might significantly decrease.  However, we should be careful in assuming that these results are generalizable.  Many bulimics are resistant to seeking treatment so it may be that those bulimics who are also depressed and/or anxious may be more likely to seek treatment.  This sample may be biased, and may not be examining a complete cross section of the bulimic population.  All the same, anxiety disorders do seem to be co-occurring with a fair number of bulimics.

Bulik et al., 1996
Bulik et al. examined lifetime anxiety disorders in women with bulimia nervosa (Bulik et al., 1996).  114 women ages 17 to 45 participated in an outpatient trial of three psychological treatments for bulimia nervosa.  All of the patients met DSM-III-R criteria for bulimia nervosa.  All of the subjects underwent a two to four hour assessment which included the Structured Clinical Interview for DSM-III-R, which was modified to obtain more information about lifetime history of eating disorders and related behaviors.  Lifetime anxiety disorders (particularly social phobia, specific phobia, and childhood overanxious disorder) were an additional diagnosis in 64% of these bulimic women.  Of all of the psychiatric disorders, anxiety disorders had the earliest mean age of onset (8 years), and even when the childhood anxiety disorders were excluded, anxiety disorders still had the earliest mean age of onset (9 years).  Within this sample, of those with concurrent anxiety disorders, the anxiety disorder occurred before the bulimia nervosa in 92%, after bulimia nervosa in 7%, and at about the same time in 1%.  These researchers also found that the presence of an anxiety disorder was related to an increase in the degree of food restriction, an increase in total personality disorders and symptoms, an earlier age of onset of any drug/alcohol dependence, a past history of anorexia nervosa.

What the researchers conclude is that anxiety disorders may be a possible pathway to bulimia nervosa.  Childhood anxiety disorders may share a biological or temperamental predisposition with bulimia nervosa, or they may be independent conditions, but the childhood anxiety disorders could increase vulnerability to development of an eating disorder later in life.  Bulik et al. cite Kendler et al. here who determined that bulimia shared genetic etiological factors with panic disorders and phobias (Kendler et al., 1998).  However, we must be careful in interpreting the findings of Bulik et al.  For one, in this  study no control group existed so it is difficult to determine anything conclusively.  Again,  a selection bias may exist because the researchers used referred patients as their sample. As in the Brewerton et al. study, bulimics who are anxious may be more likely to seek help than those who are not anxious.

Saccomani et al., 1998
Saccomani et al. examined long-term outcome and comorbidity of children and adolescents with anorexia nervosa (Saccomani et al., 1998).  Their sample was made up of 76 females and 11 males.  They looked at different psychiatric disorders to see if they had any prognostic value in terms of the outcome of these eating disorder patients.  No statistical difference was found for anxiety disorders between diagnosis and follow up. Anxiety disorders did not seem to be prognostic indicators.  Whereas Bulik et al. found that childhood anxiety disorders may be a potential pathway to bulimia nervosa, this study demonstrates that when looking at anorexia nervosa, comorbid anxiety disorders have no predictive value in terms of the outcomes for these patients.  This is an interesting finding in comparison to what Brewerton et al. predict.  Even though the two diseases studied are different, they do have some overlapping characteristics such as anxiety about weight gain and body image.  It seems interesting that the presence or absence of an anxiety disorder does not seem to have predictive value for anorexics in this study, but Brewerton et al. suggest that treating the anxiety may decrease bingeing and purging in bulimics.

Bulik et al., 1997
This study compared the prevalence and age on onset of adult and childhood anxiety disorders relative to the primary diagnosis in 68 women with anorexia nervosa, 116 women with bulimia nervosa, 56 women with major depression with no eating disorder, and 98 randomly selected controls.  The researchers were looking to see if antecedent anxiety disorders were plausible risk factors for anorexia nervosa and bulimia nervosa. The group with major depression but no eating disorder was included so as to try to determine a bit more specifically if anxiety disorders make individuals vulnerable to a
range of other psychiatric disorders or only eating disorders.  It should also be noted at this point that this is first study to have a randomized control group. Lifetime anxiety disorders were present in 60% of the women with anorexia nervosa, 57% of the women with bulimia nervosa, 48% of women with depression, and 33% of controls. Panic disorder was highest among anorexics and depressed women.  Social phobia was highest among bulimics.  Obsessive-compulsive disorder was highest in anorexics. Overanxious disorder was highest in anorexics and bulimics.  Separation anxiety disorder was highest among anorexics.  Logistic regressions strongly supported an association between anxiety disorders and anorexia nervosa, and to a lesser extent, bulimia nervosa. Again, of those with lifetime anxiety disorders, 90% of anorexic women and 94% of bulimic women reported that the onset of the anxiety disorder preceded the onset of the eating disorder.

The findings of this study suggest that early onset anxiety disorders are not necessarily specific to eating disorders since those with major depression also had many comorbid anxiety disorders.  However, certain anxiety disorders such as obsessive-compulsive disorder may indeed be more specific (in this case to anorexia nervosa).

V. Conclusion

It seems clear from both the case studies and the scientific research studies that anxiety disorders and eating disorders have a higher frequency of co-occurrence than would be expected in the general population.  The research shows that anxiety disorders tend to precede eating disorders and that specific anxiety disorders seem to be more likely to occur with either anorexia nervosa or bulimia nervosa.  More research should be done with control groups and with comparison groups with other psychiatric disorders to determine how risk-specific the anxiety disorders are for later development of eating disorders.  It is important to understand the nature of the interaction between these two sets of disorders because of the implications for disease management and treatment.  Such comorbidity has been shown to increase the severity of the symptoms and to increase impairment of daily functioning and social disability (Lecrubier, 1998).  As Chesler points out in her case studies, the interplay of the two disorders may create a situation which requires significant attention to both disorders in terms of treatment.  We should learn as much as we can about the effect of comorbidity so as to better treat patients who present with both anxiety and eating disorders.

VI.  References

American Psychiatric Association (APA). (1987).  Diagnostic and statistical manual of
     mental disorders (3rd ed., rev.).  Washington, DC:  Author.

American Psychiatric Association (APA).  (1994).  Diagnostic and statistical manual of
     mental disorders (4th ed.).  Washington, DC:  Author.

Brewerton, Timothy D., Lydiard, R. Bruce, Herzog, David B., Brotman, Andrew W.,
     OíNeil, Patrick M. & Ballenger, James C (1995).  Comorbidity of Axis I Psychiatric
     Disorders in Bulimia Nervosa.  Journal of Clinical Psychiatry.  56, 77-80.

Bulik, Cynthia M., Sullivan, Patrick F., Carter, Frances A. & Joyce, Peter R (1996).
     Lifetime Anxiety Disorders in Women with Bulimia Nervosa.  Comprehensive
     Psychiatry.  37, 368-74.

Bulik, Cynthia M., Sullivan, Patrick F., Fear, JL & Joyce, Peter R (1997).  Eating
    Disorders and Antecedent Anxiety Disorders:  A Controlled Study.  Acta Psychiatrica
     Scandinavica.  96, 101-7.

Chesler, Betty E (1995).  The Impact of Stress, Fear of Fatness, and Panic Disorder with
     Agoraphobia on Eating Disorder Symptomatology:  A Case Study.  International
     Journal of Eating Disorders.  18, 195-8.

Chesler, Betty E (1997).  Eating Disorders and Panic:  Four Cases of Pathological Coping.
     International Journal of Eating Disorders.  22, 219-22.

Durand, V. Mark & Barlow, David H (1997).  Abnormal Psychology:  An Introduction.
     Brooks/Cole:  Pacific Grove.

Herzog, David B., Nussbaum, Karin M. & Marmor, Andrea K (1996).  Comorbidity and
     Outcome in Eating Disorders.  The Psychiatric Clinics of North America.  19, 843-59.

Kendler, Kenneth S. & Gardner, Charles O (1998).  Twin Studies of Adult Psychiatric and
     Substance Dependence Disorders:  Are They Biased By Differences in the
     Environmental Experiences of Monozygotic and Dizygotic Twins in Childhood and
     Adolescence?.  Psychological Medicine.  28, 625-33.

Lecrubier, Yves (1998).  Comorbidity in Social Anxiety Disorder:  Impact on Disease
     Burden and Management.  Journal of Clinical Psychiatry.  59, 33-8.

Saccomani, L., Savoini, M., Cirrincione, M., Vercellino, F. & Ravera, G (1998).  Long-
     Term Outcome of Children and Adolescents with Anorexia Nervosa:  Study of
     Comorbidity.  Journal of Psychosomatic Research.  44, 565-71.

Wonderlich, SA & Mitchell, JE (1997).  Eating Disorders and Comorbidity:  Empirical,
     Conceptual, and Clinical Implications.  Psychopharmacology Bulletin.  33, 381-90.


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