Chapter 1 Anorexia Nervosa
PATHOPHYSIOLOGY
Anorexia nervosa is an eating disorder that typically begins in adolescence and is characterized by the refusal to maintain a body weight within the minimal range of normal for height, weight, and body frame. The patient denies the seriousness of weight loss and has a distorted body image. Despite being dangerously thin, the individual feels fat. In addition, there may be a focus on the shape and size of particular body parts (Box 1-1).
Box 1-1 Diagnostic Criteria for Anorexia Nervosa
• Refusal to maintain body weight at or above a minimally normal weight for age and height (e.g., weight loss leading to maintenance of body weight less than 85% of that expected; or failure to make expected weight gain during period of growth, leading to body weight less than 85% of that expected).
• Intense fear of gaining weight or becoming fat, even though underweight.
• Disturbance in the way in which one’s body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.
• Amenorrhea in postmenarchal females, i.e., the absence of at least three consecutive menstrual cycles. (A woman is considered to have amenorrhea if her periods occur only following hormone, e.g., estrogen, administration.)
From American Psychiatric Association: Diagnostic and statistical manual of mental disorders, ed 4, text revision (DSM-IV-TR), Washington, DC, 2000, The Association.
There are two general subtypes of anorexia nervosa. The restricting type involves severe restriction of food intake and compulsive exercising. The binge eating and purging type involves restricted dietary intake coupled with intermittent episodes of binge eating, followed by purging. Self-induced vomiting and use of ipecac, laxatives, diuretics, or enemas are common means of purging. Excessive use of appetite suppressants or diet pills is seen in both types.
Purging and semistarvation may induce electrolyte imbalance and cardiac problems, which may ultimately lead to death. Starvation creates a range of medical symptoms. Changes in growth hormone levels, diminished secretion of sex hormones, defective development of bone marrow tissue, structural abnormalities of the brain, cardiac dysfunction, and gastrointestinal difficulties are common. A notable problem associated with anorexia in adolescents is the potential for growth retardation, delay of menarche, and peak bone mass reduction. When normal eating is reestablished and laxative use is stopped, the youth may be at risk for developing medical complications.
A variety of psychologic factors are associated with anorexia nervosa. Personality traits of perfectionism and compulsiveness are common. Low self-esteem also plays a role. In many cases, weight loss is experienced as an achievement, and self-esteem becomes dependent on body size and weight. At the same time the adolescent may experience peer, familial, and cultural pressures to be thin. There is a high incidence of co-occurring mood disorders in anorexic patients. In some cases, major depression may result from nutritional deprivation. Individuals with anorexia nervosa may lack spontaneity in social situations and may be emotionally restrained. Family dynamics may play a role in development of symptoms. Eating behaviors ostensibly emerge in an unconscious attempt to gain control in cases where parents are perceived to be controlling and overprotective. For some adolescents, diminished weight and loss of secondary sexual characteristics are related to difficulty accepting maturation into adulthood. A reflection of the sociocultural ideal of thinness, disordered eating that is not severe enough to meet criteria for anorexia nervosa is common among adolescent girls in the United States and is on the rise in males.
INCIDENCE
1. More than 90% of individuals with anorexia are females.
2. Rate of incidence among those aged 15 through 24 years is 14.6% for females and 1.8% for males.
3. Mortality rates range between 6% and 15%; half the deaths result from suicide.
4. Prevalence continues to be higher in Western industrialized nations with predominantly white populations and among middle- and upper-class females. Increasing diversity in the ethnic and socioeconomic groups of those affected is being reported. For immigrants, degree of acculturation may play a role.
5. Cardiac complications occur in 87% of affected youth.
6. Renal complications occur in approximately 70% of affected youth.
