[Editor's note: This article is from 2007. Some newer treatments, and imaging and genetic discoveries, are not mentioned.]
sections include: defining anorexia and bulimia, searching for biological causes, diagnosis and treatment
The term eating disorder usually refers to anorexia nervosa and bulimia nervosa, but applies as well to similar conditions that do not quite meet the exact criteria of these two major eating disorders. The vast majority of people who suffer from eating disorders are women. Approximately 2.5 percent of females in the United States suffer from anorexia nervosa or bulimia nervosa at some time in their lives. Most sufferers are adolescents and young adults ranging in age from 10 to 30. Significantly more women suffer from variants of these disorders. Eating disorders are rare among males.
Because of publicity about eating disorders, you may well be aware of their most common symptoms: eating far less than is healthy, bingeing on food, and vomiting food back up or otherwise purging it from one’s body. People with eating disorders often learn to hide such behavior, however. A more visible sign of an eating disorder is therefore an excessive preoccupation with food and body appearance. Other suspicious signs include excessive exercising, refusal to eat foods containing high fat, refusal to eat with family members or friends, gradual weight loss or episodes of weight loss with rapid weight gain, and progressive isolation from friends and family.
Obviously, not digesting enough food is harmful. People with severe eating disorders can suffer damage to the heart, kidneys, liver, immune system, bones, and other organs because their bodies do not receive enough of the nutrients they need. These problems can be fatal. The body also suffers from the unnatural stresses of bingeing and purging.
Even beyond the issues of nutrition and physical health, eating disorders can have a devastating effect on an individual’s psychological and social well-being. Afflicted people’s isolation from family and friends, difficulty concentrating, irritability, disturbed sleep and depression can seriously interfere with their quality of life and their performance at work or school.
Defining Anorexia and Bulimia
Four major criteria define anorexia nervosa:
- Weight loss and refusal to maintain body weight in the normal range for one’s age and height.
- A morbid fear of becoming fat
- A disturbance in the way one experiences one’s current low body weight: seeing specific parts of the body, such as the abdomen and thighs, as unduly fat even when obviously underweight, and denying the seriousness of one’s low body weight.
- In women, amenorrhea, or the absence of menstruation.
There are two types of anorexia nervosa. The first is the restricting type, in which the person loses weight only by restricting food intake and exercising. The second is the binge-purge type, in which the person regularly engages in binge eating and then purging through self-induced vomiting or the misuse of laxatives, diuretics, and enemas.
Despite their refusal to eat, anorectic people think constantly about food. They may demonstrate this preoccupation by collecting recipes and preparing elaborate meals for others. They may comment incessantly about looking fat and feeling flabby and frequently gaze in the mirror to check their body form. Research on people with anorexia has shown that many have trouble even perceiving their true body size, consistently identifying it as 20 percent larger than it really is.
Bulimia nervosa is defined by five criteria:
- The person has recurrent episodes of bingeing on food, eating an excessive amount within a discrete period while feeling unable to control the eating or to stop.
- The person repeatedly uses self-induced vomiting or laxatives, diuretics, enemas, fasting, excessive exercising, or other medications to prevent weight gain.
- These behaviors occur on average at least twice a week for three months.
- The person is persistently too concerned with body shape and weight.
- The person does not meet the criteria of anorexia nervosa. If she or he does, then we call the disorder anorexia nervosa, binge-purge type.
People with bulimia nervosa will often eat huge quantities of food when alone. Family members may return home to find an empty refrigerator or empty cupboards. Bulimic people may also take frequent trips to the bathroom in order to make themselves vomit up food.
There are also people who have most of the core clinical features of anorexia nervosa or bulimia nervosa but do not meet all the criteria stated above. We classify them as having an eating disorder not otherwise specified. Examples are people who vomit after eating small amounts of food but maintain their weight within the normal range and (if they are women) continue to menstruate, or people who binge eat but do not follow these episodes with any efforts at weight reduction. The latter are often referred to as having binge-eating disorder, with the majority of these people being excessively overweight.
There is no single cause of eating disorders. Extensive research indicates that anorexia nervosa and bulimia nervosa begin with simple dieting and that a number of factors—biological, psychological, and societal—propel an individual into developing an eating disorder. The modern West’s ideal of a slender body type has been particularly powerful, and individuals who are exposed to this ideal seem to be at risk for developing an eating disorder. There has been a consistent increase in the incidence of anorexia nervosa in industrialized countries during the past three decades. In contrast, the prevalence of bulimia nervosa is remarkably consistent at the rate of 1 percent in adolescent and young adult women.
Searching for Biological Causes
Much of the research into the causes of anorexia and bulimia revolves around neurotransmitters in the brain. Animal studies have shown that eating behavior is strongly influenced by messenger chemicals in the hypothalamus. Serotonin is one such neurotransmitter, helping us to feel satiety or fullness. When researchers inject serotonin into an animal’s paraventricular nucleus, part of the hypothalamus, eating behavior is suppressed. Studies have also found that people with anorexia who have been in recovery for a long time have elevated levels of a product left over from metabolizing serotonin. It is therefore possible that having too much serotonin in the brain reinforces a person’s urge to abstain from eating.
People who suffer from anorexia nervosa, restricting type, share some personality traits and behaviors also seen in obsessive-compulsive disorder, such as a tendency to be especially rigid, inhibited, ritualistic, and perfectionistic. Researchers have long thought that people with OCD also have serotonin system abnormalities because they respond well to selective serotonin reuptake inhibitors (SSRIs).
We also see an association between low levels of serotonin and impulsive, suicidal and aggressive behavior. The bingeing and purging behaviors of bulimics suggest they have impulse-control and satiety-regulation problems. Several studies have reported impairment in the system for stimulating serotonin activity in bulimic patients. There seems to be enough evidence of such problems in both anorexia nervosa and bulimia nervosa to consider a vulnerability in the serotonergic neurotransmitter system as a risk factor for eating disorders.
Two other neurotransmitters, norepinephrine and dopamine, also influence how we eat. Studies have indicated that abnormalities in these neurotransmitters may have an effect in precipitating and sustaining eating disorders.
Research in the past two decades has suggested a genetic aspect to eating disorders as well. Psychological assessments have consistently linked anorexia nervosa to a cluster of moderately heritable personality and temperamental traits, such as obsessionality, perfectionism, and harm avoidance. Studies have found a higher lifetime prevalence of anorexia or other eating disorders in first- degree relatives of people with anorexia, and twin studies have shown that restricting anorexia nervosa was markedly higher for identical twins (66 percent) than for fraternal twins (0 percent). In a twin study on bulimia nervosa, the rate was also significantly higher in identical than in fraternal twin pairs.
Diagnosis and Treatment
People with anorexia nervosa deny the gravity of their illness and are reluctant to obtain medical treatment. Concerned family members usually bring them unwillingly to a doctor after their weight loss or eating habits have become alarming, or after girls have stopped having their menstrual periods. Even then, people with this disorder refuse to acknowledge that the symptoms are serious and are completely uninterested and resistant to treatment.
Many bulimics are ashamed of their bingeing and purging and are thus reluctant to acknowledge that behavior to their physicians. Dentists are often the first to diagnoses bulimia nervosa because they notice the erosion of tooth enamel caused by constant exposure to gastric acid from self-induced vomiting.
For people who make themselves vomit and abuse laxatives, the acute symptoms of fatigue, weakness, and fainting may bring them to a physician or even to an emergency room. People with eating disorders are well aware of what has caused such symptoms but are often reluctant to describe their behavior or to admit that the problems are serious. Family members may thus worry that the individual has cancer, a chronic infection, or a disturbance of the gastrointestinal tract.
Physicians diagnose eating disorders by obtaining information on a person’s weight, menstrual history, and eating behavior, including meals shared with family, dieting, bingeing episodes, self-induced vomiting, or abuse of laxatives and diuretics. Doctors ask questions to determine whether the individual has a preoccupation with and fear of gaining weight. They also inquire about a person’s exercise regime and about any depressive symptoms. Weight loss frequently occurs in depressive disorders (depression, bipolar disorder), which have several other features that may appear in anorexia: depressed feelings, crying spells, sleep disturbances, obsessive ruminations, and occasional suicidal thoughts.
A complete blood count is useful. People with anorexia nervosa often show a low level of white blood cells. Those who make themselves vomit are likely to have a low potassium level and an elevated level of a blood component called serum amylase.
A variety of mental health professionals specialize in the treatment of eating disorders, including psychologists and social workers. Pediatricians who practice adolescent medicine may specialize in both the medical and psychological care of their patients. However, adolescents with severe eating disorders should have psychotherapy from a well-trained psychotherapist in addition to pediatric services. Psychiatrists may also specialize in the treatment of eating disorders. Some psychiatrists who have had special training in internal medicine and pediatrics can treat both the psychological and medical needs of an adolescent with an eating disorder. For the great majority of adolescent and adult sufferers, a psychiatrist’s medical training is sufficient. Early diagnosis and intensive early treatment is extremely important for people with eating disorders. Studies have shown that if people with anorexia stay below their normal weight range for longer than six years, their chances of recovery are almost nonexistent. Children treated for eating disorders have a significantly better outcome than patients first treated over the age of 18.
People with anorexia nervosa need treatment that includes medical care, education, and individual therapy. Studies have shown that children and adolescents do better if they have family therapy as well. Nutritional counseling and medication can also be useful, but treatment should never rely on drugs alone.
Chlorpromazine may help a severely ill person who is overwhelmed with constant thoughts of losing weight and has incessant behavioral rituals. The newer atypical antipsychotic medications, such as olanzapine (Zyprexa), are also helpful for such individuals. Cyproheptadine (Periactin) in high doses (up to 28 mg per day) can facilitate weight gain for people with anorexia nervosa, restricting type, and may have a mild antidepressant effect. Fluoxetine (Prozac), an SSRI, has been shown to be useful in preventing relapse into anorexia nervosa and may specifically target the obsessive-compulsive behaviors involving food and weight control.
Almost all antidepressants, including desipramine (Desyrel), imipramine (Tofranil), methylphenidate (Ritalin), amitriptyline (Elavil), and fluoxetine (Prozac), have been shown to be effective in reducing the binge-purge behavior in those with bulimia nervosa by 50 percent to 60 percent. However, the rate of complete abstinence from bingeing and purging in all studies was only about 25 percent.
Cognitive behavioral therapy (CBT) is the first line of treatment for bulimia nervosa. Individuals are encouraged to identify the emotions involved in their binge-purge episodes and perception of body image. CBT interrupts the cycle of bingeing and purging and alters people’s dysfunctional thoughts and beliefs about food, weight, body image, and overall self-concept. About 40 percent to 50 percent of bulimic patients stop bingeing and purging at the end of treatment (16–20 weeks). Another 30 percent who do not improve immediately reach full recovery one year after treatment. CBT is also the psychotherapy of choice for anorexia nervosa.
The severity of illness will determine the intensity of treatment for an eating disorder patient. A specialized eating disorder inpatient unit is necessary for those requiring intensive medical management or monitoring for suicidal and impulsive behaviors. Less severely ill people may do well in a partial hospitalization or day program, and those with no serious medical complications and a weight loss of less than 80 percent below the normal range should begin with intensive outpatient treatment.
We expect 25 percent of anorectics to fully recover. About 25 percent will continue to have severe problems with weight control and eating behaviors and will not be able to function adequately at work and in personal relationships. The remaining 50 percent or so will continue to have mild symptoms, such as preoccupation with body weight, that will cause them to practice restrictive eating or controlled exercising but will not interfere with how they function at work or, in most cases, at home. About 40 percent of anorexia nervosa patients will go on to develop normal-weight bulimia nervosa.
Mortality rates for people diagnosed with anorexia nervosa are 6.6 percent after ten years, and 18 percent to 20 percent after 30 years. Most follow-up studies show that anorectic patients with an earlier age of onset (under age 18) have a better chance of recovering. Purging behavior, self-induced vomiting, and laxative abuse usually indicate a worse outcome.
For bulimia nervosa, 50 percent of people fully recover. The remaining patients are not symptom-free: 30 percent have a less severe form of the disorder, and 20 percent continue to meet full criteria. Relapse is a serious problem: about one third of recovered bulimics relapse within four years after treatment. Mortality has been estimated to be below 3 percent. There is some suggestion that personality disorders marked by problems with impulse control suggest a worse prognosis in patients with bulimia nervosa.
Researchers continue to seek clues to the biological basis of these disorders. Imaging studies may identify particular areas of the brain affected by them, as well as impaired receptor functioning for various neurotransmitters. We need more studies to determine new treatment strategies that will help people with eating disorders overcome these difficult and disabling conditions.
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