THE PREVALENCE OF ANOREXIA NERVOSA,,

BULIMIA NERVOSA, AND BINGE EATING DISORDER

Melissa Machen





INTRODUCTION

How prevalent is anorexia nervosa, bulimia nervosa, and other eating disorders? Without the knowledge of research, one is likely to think eating disorders are quite prevalent in society today. However, research proves that eating disorders, in general, are not as prevalent as one might think without any knowledge of the subject. Prevalence of an eating disorder refers to the number of cases of an eating disorder within a population. When discussing the prevalence of anorexia nervosa, bulimia nervosa, and eating disorders, it is important to realize and understand the risk factors and characteristics that help to better explain the prevalence of such disorders. This paper will discuss the diagnostic criteria used to diagnose anorexia nervosa, bulimia nervosa, and eating disorders, as well as the risk factors and characteristics involved with each disorder. The prevalence of eating disorders in college men will also be discussed along with the risk factors and characteristics that lead to these prevalence rates.

Prevalence and Diagnostic Criteria for Anorexia Nervosa

In order to understand the importance of the prevalence of anorexia nervosa it is important to generally understand the DSM IV criteria for anorexia nervosa. In order to qualify for diagnosis as an anorexic, a Patient must maintain an abnormally low weight (I 5% below expected weight for height and age). One must also have severe concerns about shape and weight, which is usually seen as an intense fear of gaining weight, in order to be classified as an anorexic. One who qualifies as anorexic also has low self evaluation about shape and weight. Also, in post-menarchal females, there must be the presence of amenorrhea, or the absence of at least three consecutive menstrual cycles. (Fairbum and Wilson, 1993, 9). There are several types of anorexia nervosa (restricting type and binge eating/purging type), but these distinct classifications are not relevant to this discussion.

After discussing the criteria used to establish the presence of an anorexia nervosa disorder, the discussion of prevalence rates of anorexia nervosa is necessary. Eagles et al (1995) conducted a study of the prevalence rates of anorexia nervosa by comparing referral rates of patients. They acknowledge that a number of studies on this subject have been conducted and that the outcomes have been conflicting. Eagles et al (1995) recognize that these conflicting results can be explained by the changes in admissions practices, changes in the frequency of referrals and an increase in public awareness (Eagles et al, 1995, 1266). Studying the incidence of referral rates is necessary in order to determine the prevalence of anorexia nervosa because referral rates are a direct measurement of the number of cases within a given population. The study by Eagles et al (1995) found that referral rates of anorexia nervosa have risen in the past two decades and these rates have a direct influence on prevalence rates. Therefore, the researchers conclude from the increase in the incidence of referral rates and increased public awareness that the prevalence of anorexia nervosa has also risen, but they do not give a prevalence rate. Therefore, the increase in referral rates and increased public awareness of anorexia nervosa have increased the prevalence rate but the real effect is unknown.

Another study by Walters and Kendler (I 995) looked at prevalence rates of anorexia nervosa as well as risk factors and characteristics that influenced the prevalence rate of this eating disorder. This study differentiated between definite cases of anorexia nervosa and "anorexia-like syndromes" (Walters and Kendler, 1995, 64). This distinction is important because there is a definite distinction between the two classifications in terms of prevalence rates of anorexia. Walters and Kendler found that prevalence rates of anorexia nervosa ranged from 0. 10% to 1.0%. These rates varied due to demographic characteristics of the sampling population, the age of the sample studied and other criteria. The prevalence rates of anorexia nervosa differ greatly from the rates of "anorexia-like syndrome" which are 3.43%. This discrepancy in these prevalence rates can be indicative of the fact that partial syndrome anorexia is more common than anorexia nervosa which is probably a direct result of the limiting criteria for diagnosing anorexia nervosa.

Another important aspect of the study by Walters and Kendler (1995) is the discussion they lend to the similarities of risk factors between anorexia nervosa and partial syndrome anorexia. They found similarities in rates of comorbidity in patients with anorexia and major depression. The mean age of onset was 18 in both groups. They also found a higher prevalence of anorexic symptoms among patients in higher socioeconomic classes. This finding could be due to an underrating of the disorder in lower socioeconomic classes or greater resources for referral, diagnosis and treatment resources among the higher socioeconomic groups. (Walters and Kendler, 1995, 70). These findings suggest that the risk factors and characteristics are quite similar between the two groups despite the fact that one group is formally diagnosed as having anorexia nervosa.

Prevalence and Diagnostic Criteria for Bulimia Nervosa

As with anorexia nervosa, it is important to discuss the diagnostic criteria for bulimia nervosa in order to understand the importance if the prevalence rates of bulimia nervosa. The first diagnostic criterion for bulimia nervosa are the presence of recurrent episodes of binge eating. The second criterion is the presence of extreme compensatory behavior to control body shape and weight. And lastly, concurrent with the criteria for anorexia nervosa, one must be overly concerned with shape and weight in judging self worth. As with anorexia nervosa, bulimia nervosa takes two forms (purging and non-purging types) but these are relatively unimportant in the discussion of the prevalence of bulimia nervosa. (Fairburn and Wilson, 1993, 8).

A study by Fairbum et al (I 996) discusses the prevalence of bulimia nervosa in terms of clinical cases and community cases. This study found a prevalence rate of bulimia nervosa to be between 1% and 2%. However, this rate is somewhat distorted because of the number of cases that are not being treated and are therefore, unreported. As for characteristics and risk factors of the two groups, there were some similarities and differences. The clinical and community groups did not differ in age or other demographic characteristics. The clinical patients, as might be expected, had a more sever case of the disorder and weighed significantly less than did the community subjects. The two groups did not differ significantly in the age of onset of bulimia nervosa or the duration of the eating disorder. The two groups also had similar levels of comorbidity and alcohol abuse. Parental obesity was more prevalent in the community swnple.

Therefore, this study suggests, as did the study by Walters and Kendler (I 995) about anorexia nervosa, that whether or not subjects are diagnosed as having a complete case of bulimia nervosa according to the DSM IV criteria has little effect on presence of the risk factors and other characteristics of bulimia nervosa. Therefore, this suggests that the prevalence of bulimia nervosa, and anorexia nervosa, may be higher than is indicated because of a sampling bias and cases that are not reported or considered in the studies that are conducted. Another study of the prevalence of bulimia nervosa was conducted by Garfinkel et al (1995). This study found that bulimia nervosa had a lifetime prevalence rate of 1. 1% in women aged 16-65. This finding differed from that of Bushnell et al. and Kendler et al who found prevalence rates of 1.6% and 2.8% respectively. This study by Garfinkel et al (I 995) also noted a similarity in comorbidity rates among clinical and community samples, but stated that the similarity may be due to the fact that clinical samples comorbidity may be due to the fact that more subjects seek help when two disorders are present. Therefore, again, the prevalence rates of bulimia nervosa seem to be fairly consistent across studies that have been conducted but they still seem to be under representative due to sampling bias and other contributing factors.

College Men and Eating Disorders

The majority of the literature and studies focus on eating disorders and women, but men, too, experience eating disorders. Although, the rates of eating disorders are relatively smaller in men than in women, there are similarities between men and women concerning eating disorders. Olivardia et al (1995) found the prevalence rate of anorexia nervosa in men to be 0.02% and

bulimia nervosa to be between 0.1 and 0.5%. These rates are considerably less than the prevalence rates of eating disorders in women, but they are still significant, They also acknowledge that these rates of eating disorders in men may be under representative of the true population due to a reluctance on the part of men to seek treatment and therefore cases go undetected. Also, the sample that Olivardia et al (1995) used was composed of only college men which may not be characteristic of the general population of men as a whole. However, the fact that eating disorders are not just a female problem must be acknowledged and more research needs to be conducted.

Bibliography


Bruce, Bonnie and Denise Wilfley: Binge eating among the overweight population: a serious and prevalent problem. Journal of the American Dietetic Association 1996; 96:58-66,

Bushnell, JA, E. Wells, AR Homblow, Oakley-Browne, and P Joyce: Prevalence of three bulimia syndromes in the general population. Psychological Medicine 1990; 20: 671-680.

Eagles, John, Maureen Johnston, David Hunter, Mairead Lobban, and R Harry: Increasing incidence of anorexia nervosa in the female population of northeast Scotland. The American Journal of Psychiatry 1995; 152: 1266-1275.

Fairbum, Christopher, Sarah Welch, Patricia Norman, Marianne O'Connor, and Helen Doll: Bias and bulimia nervosa: how typical are clinic cases? The American Journal of Psychiatry 1996; 153:386-394.

Fairbum, Christopher and Terence Wilson. (1993). Binge Eating. New York: Guilford Press.

Garfinkel, Paul, Elizabeth Lin, Paula Goering, and Cathy Spegg: Bulimia nervosa in a Canadian community sample: prevalence and comparison of subgroups. The American Journal of Psychiatry 1995; 152: 1052-1062.

Kendler, KS, Neale Maclean, R. Kessler, A. Heath, and L. Eaves: The genetic epidemiology of bulimia nervosa. American Journal of Psychiatry 199 1; 1627-163 7.

Olivardia, Roberto, Harrison Pope, Jr., Barbara Mangweth, and James Hudson: Eating disorders in college men. American Journal of Psychiatry 1995; 152:1279-1291.

Walters, Ellen, and Kenneth Kendler: Anorexia nervosa and anorexic-like syndromes in a population based female twin sample. The American Journal of Psychiatry 1995- 152: 64-75.


 

 

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