While depression and stress may contribute to a substantial percent of cases of obesity, they are considered the leading causes of eating disorders. Most mental health professionals concur that the origins of eating disorders can be traced to behavioral or psychological difficulties. Anger and impulsive behavior have been associated with binge-eating disorders, but even such mild mental health or social problems as shyness or lack of self-confidence can lead to social withdrawal, isolation, and a sedentary lifestyle that promotes weight gain and ultimately obesity. According to the National Institute of Mental Health (NIMH), eating disorders frequently coexist with other mental disorders, including depression, substance abuse, and anxiety disorders.
At first glance, eating disorders appear to center on preoccupations with food and weight; however, mental health professionals believe these disorders are often about more than simply food. In addition to psychological factors that may predispose people to eating disorders, including diminished self-esteem, depression, anxiety, loneliness, or feelings of lack of control, a variety of interpersonal and social factors have been implicated as causal factors for these disorders. Interpersonal issues that may increase risk for developing eating disorders include troubled family and personal relationships, difficulty expressing emotions, a history of physical or sexual abuse, or the experience of being teased, taunted, or ridiculed about body size, shape, or weight. Social factors that may contribute to eating disorders include sharply restricted, rigid definitions of beauty that exclude people who do not conform to a particular body weight and shape; cultures that glorify thinness and overemphasize the importance of obtaining a 'perfect body'; and cultures that judge and value people based on external physical appearance rather than on such internal qualities as character, intellect, generosity, and kindness. Appearance-driven concerns, rather than health needs, continue to motivate many obese individuals to lose weight. Societal pressures reinforce these appearance-driven concerns by portraying obese individuals in a negative manner.
A related consideration that further complicates pinpointing the origins of eating disorders is the extent to which temperament interacts with interpersonal and social factors to promote eating disorders. Researchers and mental health professionals observe that such temperamental tendencies as perfectionism, compulsivity, impulsivity, and other behavioral, cognitive, and emotional leanings seem to predispose to eating disorders.
Binge-Eating Disorders
Binge eating is a common problem among people who are overweight and obese. In addition to consuming unusually large amounts of food in a single sitting, binge eaters generally suffer from low mood and low alertness, and experience uncontrollable compulsions to eat. They experience food cravings prior to binge episodes and feelings of discontent, dissatisfaction, and restlessness following binges.
The Weight-control Information Network (WIN; a service of the NIDDK) describes binge-eating disorder as the most common eating disorder, affecting approximately 2% of American adults or about four million people in the United States (http://win.niddk.nih.gov/publications/binge.htm, September 2004). In Eating Disorders: Facts about Eating Disorders and the Search for Solutions (2001), the NIMH estimates that between 2% and 5% of Americans experience binge-eating disorder in a six-month period. The Weight-control Information Network estimates that approximately 10% to 15% of people who are mildly obese and diet to lose weight on their own or with commercial weight-loss programs have binge eating disorder. In contrast, the National Women's Health Information Center (sponsored by the Office on Women's Health in the U.S. Department of Health and Human Services) cites research suggesting that binge eating disorder is the most common eating disorder, affecting about one-third of obese participants in weight-loss programs (BodyWise Handbook, 3rd ed., April 2005, http://www.womens-health.gov/BodyImage/bodywise/bp/BodyWise.pdf). Although the disorder is even more common in people who are severely obese, normal-weight people also can develop the disorder. Binge-eating disorder is more prevalent among women than among men; three women for every two men have it, and it affects African-Americans as often as whites. People who suffer from binge eating often:
- Feel that eating is out of their ability to control
- Eat amounts of food most people would think are unusually large
- Eat much more quickly than usual during binge episodes
- Eat until the point of physical discomfort
- Consume large amounts of food, even when they are not hungry
- Eat alone because they feel embarrassed about the amount of food they eat
- Feel disgusted, depressed, or guilty after overeating.
Emotional functioning is known to be substantially worse in people with binge-eating problems than in people who are not binge eaters. Catherine Greeno and her colleagues at the Western Psychiatric Institute and Clinic at the University of Pittsburgh Medical School monitored and compared the eating habits of women with binge-eating disorder to eating habits of weight- and age-matched women without the disorder. The results of their study were reported in 'Binge Antecedents in Obese Women with and without Binge Eating Disorder' (Journal of Consulting and Clinical Psychology, vol. 68, no. 1, February 2000). The researchers found that binge episodes were preceded by feelings of tension, poor mood, loss of control over eating behavior, and craving for sweets. Binge eating often occurred when the subjects were home alone.
The investigators were surprised to find that binge eating occurred among the women selected to serve as the control group; however, they noted that it was not nearly as frequent nor was it preceded by the same feelings that preceded binges in the affected subjects. The investigators asserted that the principle contribution of their research was to demonstrate that poor mood immediately precedes binge episodes in the disorder. They observed that while mood is worse overall for women with binge-eating disorder, mood is especially poor before binge episodes. They interpreted this finding as suggesting design of treatment approaches that focus on alternative ways to deal with especially poor mood.
In an effort to identify the risk factors for binge-eating disorder, researchers compared women diagnosed with binge-eating disorder to those with no history of an eating disorder. They concluded that childhood obesity and the presence of eating problems among other family members were reliable, specific risk factors for binge-eating disorder. Subjects with binge-eating disorder also reported more family discord and felt they had more parental demands placed on them than the subjects with no history of an eating disorder (Ruth H. Striegel-Moore et al., 'Toward an Understanding of Risk Factors for Binge-Eating Disorder in Black and White Women: A Community-Based Case-Control Study.' Psychological Medicine, vol. 35, no. 6, June 2005).
Some Dieters Are Consumed by Eating Disorders
Society today is preoccupied with body image. Americans are constantly bombarded with images of very thin, beautiful young women and lean, muscular men in magazines, on television, on billboards, and in the movies. The advertisers of many products suggest that to be thin and beautiful is to be happy. Many prominent weight-loss programs reinforce this suggestion. Well-balanced, low-fat food plans, or other diets that restrict carbohydrates or calories combined with exercise can help most overweight people achieve a healthier weight and lifestyle. Dieting to achieve a healthy weight is quite different from dieting obsessively to become 'model' thin, which can have consequences ranging from mildly harmful to life-threatening. Table 3.1 enumerates the health consequences of eating disorders.
TABLE 3.1
Health consequences of eating disorders
- Eating disorders are serious, potentially life-threatening conditions that affect a emotional and physical health.
- Eating disorders are not just a "fad" or a "phase." People do not just "catch" an eating disorder for a period of time. They are real, complex, and devastating conditions that can have serious consequences for health, productivity, and relationships
- People struggling with an eating disorder need to seek professional help. The earlier a person with an eating disorder seeks treatment, the greater the likelihood of physical and emotional recovery.
Health consequences of anorexia nervosa: In anorexia nervosa's cycle of self-starvation the body is denied the essential nutrients it needs to function normally. Thus, the body is forced to slow down all of its processes to conserve energy, resulting in serious medical consequences:
- Abnormally slow heart rate and low blood pressure, which mean that the heart muscle is changing. The risk for heart failure rises as the heart rate and blood pressure level sink lower and lower.
- Reduction of bone density (osteoporosis), which results in dry, brittle bones.
- Muscle loss and weakness.
- Severe dehydration, which can result in kidney failure.
- Fainting, fatigue, and overall weakness.
- Dry hair and skin; hair loss is common.
- Growth of a downy layer of hair called lanugo all over the body, including the face, in an effort to keep the body warm.
Health consequences of bulimia nervosa: The recurrent binge-and-purge cycles of bulimia can affect the entire digestive system and can lead to electrolyte and chemical imbalances in the body that affect the heart and other major organ functions. Some of the health consequences of bulimia nervosa include:
- Electrolyte imbalances that can lead to irregular heartbeats and possibly heart failure and death. Electrolyte imbalance is caused by dehydration and loss of potassium and sodium from the body as a result of purging behaviors.
- Potential for gastric rupture during periods of bingeing.
- Inflammation and possible rupture of the esophagus from frequent vomiting.
- Tooth decay and staining from stomach acids released during frequent vomiting.
- Chronic irregular bowel movements and constipation as a result of laxative abuse.
- Peptic ulcers and pancreatitis.
Health consequences of binge eating disorder: Binge eating disorder often results in many of the same health risks associated with clinical obesity. Some of the potential health consequences of binge eating disorder include
- High blood pressure
- High cholesterol levels
- Heart disease as a result of elevated triglyceride levels.
- Secondary diabetes
- Gallbladder disease
SOURCE: "Health Consequences of Eating Disorders," National Eating Disorders Association, http://www.nationaleatingdisorders.org/nedaDir/files/documents/handouts/HlthCnsq.pdf (accessed January 12, 2006)
According to the NIMH, dieting plays a role in the onset of two serious eating disorders—anorexia nervosa and bulimia. Preteens, teens, and college-age women are at special risk. In fact, more than 90% of those who develop an eating disorder are young women between the ages of twelve and twenty-five, although researchers are beginning to report rising rates of anorexia and bulimia among men. No one knows exactly how many men and teenage boys are afflicted. Until recently, there has been a lack of awareness that eating disorders can be a problem for males, perhaps because men are more likely to mask the symptoms of eating disorders with excuses and rationales such as preventing heart disease or diabetes or trying to build a more muscular physique. Studies suggest that for every ten women with an eating disorder, one male is afflicted. About 5%-15% of those with anorexia or bulimia and 35% of people with binge-eating disorders are male.
Anorexia Nervosa
Anorexia nervosa involves severe weight loss—a minimum of 15% below normal body weight. Anorexic people literally starve themselves, even though they may be very hungry. For reasons that researchers do not yet fully understand, anorexics become terrified of gaining weight. Both food and weight become obsessions. They often develop strange eating habits, refuse to eat with other people, and exercise strenuously to burn calories and prevent weight gain. Anorexic individuals continue to believe they are overweight even when they are dangerously thin.
This condition often begins when a young woman who is slightly overweight, or normal weight starts to diet to lose weight. Upon achieving the desired weight loss, she redoubles her efforts to lose weight and dieting becomes an obsession that may eclipse other interests. Affected individuals take pleasure in how well they can avoid food consumption and measure their self-worth by their ability to lose weight. Eating and weight gain are perceived as weaknesses and personal failures.
The medical complications of anorexia are similar to starvation. When the body attempts to protect its most vital organs, the heart and the brain, it goes into 'slow gear.' Monthly menstrual periods stop, and breathing, pulse, blood pressure, and thyroid function slow down. The nails and hair become brittle, and the skin dries. Water imbalance causes constipation and the lack of body fat produces an inability to withstand cold temperatures. Depression, weakness, and a constant obsession with food are also symptoms of the disease. In addition, personality changes may occur. The person suffering from anorexia may have outbursts of anger and hostility or may withdraw socially. In the most serious cases, death can result.
Bulimia
The person who has bulimia eats compulsively and then purges (gets rid of the food) through self-induced vomiting, use of laxatives, diuretics, strict diets, fasts, exercise, or a combination of several of these compensatory behaviors. According to surveys cited by the NIMH in Eating Disorders, 2% to 5% of Americans engage in binge eating, and about half of those with anorexia will turn to bulimia—binge eating and purging. Bulimia often begins when a young person is disgusted with the excessive amount of 'bad' food consumed and vomits to rid the body of the calories.
Many bulimics are at a normal body weight or above due to their frequent binge-purge behavior, which can occur from once or twice a week to several times a day. Those bulimics who maintain normal weights may manage to keep their eating disorders secret for years. As with anorexia, binge-eating disorder usually begins during adolescence, but many bulimics do not seek help until they are in their thirties or forties.
Binge eating and purging is dangerous. In rare cases, bingeing can cause esophageal ruptures, and purging can result in life-threatening cardiac (heart) conditions because the body loses vital minerals. The acid in vomit wears down tooth enamel and the stomach lining and can cause scarring on the hands when fingers are pushed down the throat to induce vomiting. The esophagus may become inflamed, and glands in the neck may become swollen.
Bulimics often talk of being 'hooked' on certain foods and needing to feed their 'habits.' This addictive behavior carries over into other areas of their lives, including the likelihood of alcohol and drug abuse. Many bulimic people suffer from coexisting medical or mental health problems, such as severe depression, which increases their risk for suicide.
Causes of Eating Disorders
Evidence suggests a genetic component to susceptibility to eating disorders. For example, in the general population the chance of developing anorexia is about one in 200, but when a family member has the disorder, the risk increases to one in thirty. Twin studies demonstrate that when one twin is affected there is a 50% chance the other will develop anorexia. In 2001 Dutch researchers examined the DNA (deoxyribonucleic acid, the material of heredity) of 145 anorexia patients and found that 11% carried the same genetic mutation. The mutation was of a gene that manufactures AgRP (Agouti Related Protein), which stimulates the desire to eat. The researchers hypothesized that a deficiency of AgRP may be involved in anorexia.
Bulimics and anorexics seem to have different personalities. Bulimics are likely to be impulsive (acting without thought of the consequences) and are more likely to abuse alcohol and drugs. Anorexics tend to be perfectionists, good students, and competitive athletes. They usually keep their feelings to themselves and rarely disobey their parents. Bulimics and anorexics share certain traits: they lack self-esteem, have feelings of helplessness, and fear gaining weight. In both disorders, the eating problems appear to develop as a way of handling stress and anxiety.
The bulimic consumes huge amounts of food (often junk food) in a search for comfort and stress relief. The bingeing, however, brings only guilt and depression. On the other hand, the anorexic restricts food to gain a sense of control and mastery over some aspect of her life. Controlling her weight seems to offer two advantages—she can take control of her body, and she can gain approval from others.
Psychological theories posited to explain the origins of bulimia include conflicted relationships between mothers and daughters, attempts to control one's own body in the face of seemingly uncontrollable family or other interpersonal relationships, or ambivalence about sexual development and attention. The latter theory also has been used to explain overweight and obesity in teen-aged girls and young women—as protection from or defense against attention from males that may make them fearful or uncomfortable.
Occurrence of Eating Disorders
Individuals with eating disorders usually come from white, middle- or upper-class families. The NIMH noted that while eating disorders have increased substantially in industrialized countries during the past twenty years, they are almost unheard of in developing countries. Thinness is not necessarily admired among all people throughout the world, especially in countries where hunger is not a matter of choice.
Estimates of the prevalence of eating disorders vary in part because secretiveness and shame prevent many cases from being reported. In 2000 the American Psychiatric Association Work Group on Eating Disorders, projected the lifetime prevalence (the number of people or proportion of a population that will have a disorder at some time in their lives) among females as 0.5%-3.7% for anorexia nervosa and 1.1%-4.2% for bulimia nervosa. The lifetime prevalence of binge eating was estimated as 2%-5% for males and females. (Practice Guideline for the Treatment of Patients with Eating Disorders, 2nd edition, 2000, http://www.psych.org/psych_pract/treatg/pg/eating_revisebook_index.cfm).
The National Women's Health Information Center names eating disorders as a key health issue affecting from 1% to 4% of young women in the United States. The Center also observes that eating disorders often coexist with other high-risk health behaviors such as tobacco, alcohol and drug use, delinquency, unprotected sexual activity and suicide attempts.
A recent study examined the relationship between dieting, binge eating disorder and alcohol use in female college students. The University of Wisconsin researchers found a relationship between dieting and bingeing severity and the frequency, intensity and negative consequences of alcohol use in the students. In fact, dieting and bingeing was more closely associated with alcohol use than were such factors as depression, age at which drinking began, or parents' drinking history. Further, the severity of the disordered eating behavior was linked to the occurrence of negative consequences of alcohol use, including blackouts and unintended sexual activity. The researchers concluded that destructive eating behaviors are often associated with harmful alcohol use (Dean D. Krahn et al., 'Pathological Dieting and Alcohol Use in College Women—A Continuum of Behaviors.' Eating Behaviors, vol. 6, no.1, January 2005).
According to the National Eating Disorders Association in Statistics: Eating Disorders and Their Precursors (http://www.nationaleatingdisorders.org/), conservative estimates of the prevalence of eating disorders in the United States project that as many as ten million women and one million men are affected. An estimated 35% of normal dieters progress to the pathological, extreme dieting that is a precursor of eating disorders. The Eating Disorders Coalition for Research, Policy & Action reports that the incidence of eating disorders has doubled since the 1960s and that mortality attributable to eating disorders is as high as 20%—the highest mortality rate of any mental illness (http://www.eatingdisorderscoalition.org/reports/statistics.html).
Treatment of Eating Disorders
Generally a physician treats the medical complications of the disorder, while a nutritionist advises the affected individual about specific diet and eating plans. To help the person with an eating disorder face his or her underlying problems and emotional issues, psychotherapy is usually necessary. People with eating disorders, whether they are normal weight, overweight, or obese, should seek help from a mental health professional such as a psychiatrist, psychologist, or clinical social worker for their eating behavior. Sometimes the challenge is to convince people with eating disorders to seek and obtain treatment; other times it is difficult to gain their adherence to treatment. Many anorexics deny their illness, and getting and keeping anorexic patients in treatment can be difficult. Treating bulimia is similarly difficult. Many bulimics are easily frustrated and want to leave treatment if their symptoms are not quickly relieved.
Several approaches are used to treat eating disorders. Cognitive-behavioral therapy (CBT) teaches people how to monitor their eating and change unhealthy eating habits. It also teaches them how to change the way they respond in stressful situations. CBT is based on the premise that thinking influences emotions and behavior—that feelings and actions originate with thoughts. CBT posits that it is possible to change the way people feel and act even if their circumstances do not change. It teaches the advantages of feeling, at worst, calm when faced with undesirable situations. CBT clients learn that they will confront undesirable events and circumstances whether they become troubled about them or not. When they are troubled about events or circumstances, they have two problems—the troubling event or circumstance, and the troubling feelings about the event or circumstance. Clients learn that when they do not become troubled about trying events and circumstances they can reduce the number of problems they face by half.
Interpersonal psychotherapy (IPT) helps people look at their relationships with friends and family and make changes to resolve problems. Interpersonal psychotherapy is short-term therapy that has demonstrated effectiveness for the treatment of depression. According to the International Society for Interpersonal Psychotherapy, IPT does not assume that mental illness arises exclusively from problematical interpersonal relationships (http://www.interpersonalpsychotherapy.org/). It does emphasize, however, that mental health and emotional problems occur within an interpersonal context. For this reason, the therapy aims to intervene specifically in social functioning to relieve symptoms.
Like other forms of psychotherapy, IPT may be used in conjunction with medications. Since eating disorders frequently recur, it is recommended that successful short-term treatment be combined with ongoing maintenance therapy, such as monthly sessions following completion of the short-term phase.
Group therapy has been found helpful for bulimics, who are relieved to find that they are not alone or unique in their binge-eating behaviors. A combination of behavioral therapy and family systems therapy is often the most effective with anorexics. Family systems therapy considers the family as the unit of treatment, and focuses on relationships and communication patterns within the family rather than the personality traits or symptoms displayed by individual family members. Family systems theory considers the family as an entity that is more than the sum of its individual members and uses 'systems theory' to determine family members' roles within the system as a whole. Problems are addressed by modifying the system rather than trying to change an individual family member. People with eating disorders who also suffer from depression may benefit from antidepressant and antianxiety medications to help relieve coexisting mental health problems.
A long-term study (approximately 11.5 years) of 173 young women diagnosed with bulimia reiterated the strong hold that eating disorders have on their victims (P. K. Keel et al., 'Long-Term Outcome of Bulimia Nervosa' (Archives of General Psychiatry, vol. 56, no. 1, January 1999). At the final follow-up, 30% of the patients still showed symptoms of eating disorders. Eighteen percent were diagnosed with ' eating disorder not otherwise specified,' 11% with bulimia, and 1% with anorexia nervosa.
Of the 70% in remission, one-third had achieved only partial remission. Patients who had longer periods of symptoms before beginning treatment and those who had a history of substance abuse were less likely to be successful. The results of this study underscore the observation that the earlier the eating disorder is diagnosed and treated, the more likely the patient will recover to a healthy weight.
Recovery from eating disorders is uneven. The Eating Disorders Coalition for Research, Policy & Action characterized recovery as a process that frequently entails multiple re-hospitalizations, limited ability to work or attend school, and limited capacity for interpersonal relationships. About one-third of sufferers recover after an initial episode and treatment, another third fluctuate between recovery and relapse, and the remaining one-third suffer chronic decline and deterioration.
In part, eating disorders are difficult to treat effectively because many sufferers resist entering treatment and/or fail to complete treatment programs. Recently, researchers examined the factors leading to nonacceptance and noncompletion (dropping out) of a specific treatment plan—cognitive-behavioral therapy, fluoxetine hydrochloride, or their combination for one year to treat anorexia nervosa. Of the 122 subjects with diagnosed anorexia nervosa, eighty-nine accepted treatment; however, more than half (55%) dropped out of treatment. More than two-thirds (68%) of those who dropped out cited 'dissatisfaction with some aspect of the treatment' as their reason for noncompletion. While the researchers did not pinpoint the reasons for nonacceptance and noncompletion, their study offered some clues and direction for further investigation. For example, the study found that subjects with high self-esteem were more likely than those with low self-esteem to complete treatment. As a result, the researchers suggested that remedies must be identified to 'improve acceptance of treatment and reduce dropout in those patients with low obsessive preoccupation and low self-esteem' (Katherine Halmi et al., 'Predictors of Treatment Acceptance and Completion in Anorexia Nervosa: Implications for Future Study Designs.' Archives of Psychiatry, vol. 62, no. 7, July 2005).
Another recent study reconfirmed the finding that while hospital treatment of people with anorexia is often successful, 30% to 70% of patients suffer relapses when they are discharged back into the community. Robin Sysko of Rutgers University and her colleagues wanted to find out whether current treatment for anorexia successfully addresses severe caloric restriction and other characteristic features of anorexia nervosa. To do this, they scrutinized eating behavior among people with anorexia nervosa before and immediately after treatment that restored their weight and compared these behaviors to those of control subjects.
They observed twelve anorexic patients and twelve individuals without eating disorders who were asked to consume a strawberry yogurt shake, which they were told would be their lunch for the day. They were also told to consume as much as they wanted. The yogurt shake was in an opaque container and was drunk with a straw so that the subjects could not see the shake. They were also not told the contents of the shake or how many calories it contained. The anorexic patients were tested when they were admitted for treatment, and re-tested after they had reached 90% of their ideal body weight.
Before treatment, anorexic patients consumed an average 103.97 g (3.67 ounces) of the shake, which increased to an average of 178.03 g (6.3 ounces) after treatment. However, in both instances, control subjects consumed significantly more than anorexic patients, at an average of 489.58 g (17.3 ounces). The researchers observed that subjects with anorexia found the experiment difficult and anxiety-provoking because they were unable to see the shake and control their calorie intake. This was despite the fact that subjects treated for anorexia displayed significant decreases in psychological and eating-disordered symptoms after they had regained weight. The researchers believed their findings underscored the need to intervene with anorexics who have left an intensive treatment program. They hope to devise strategies to help normalize patients' eating behavior outside the hospital, for example by helping reduce their anxiety and fear about eating unknown quantities of food ("Eating Behavior among Women with Anorexia Nervosa," American Journal of Clinical Nutrition, vol. 82, no. 2, August 2005).
NEW DIRECTIONS IN RESEARCH AND TREATMENT
Eating Disorders: Facts about Eating Disorders and the Search for Solutions (Bethesda, MD: NIMH, National Institutes of Health, 2001) reported that the results of NIMH research are aiding both the understanding of eating disorders and their treatment. Research on intervening in the binge-eating cycle has demonstrated that initiating structured patterns of eating enables people with eating disorders to experience less hunger, less deprivation, and fewer negative feelings about food and eating. When the two key predictors of bingeing—hunger and negative feelings—are reduced, the frequency of binges declines.
Continued study of the human genome promises the identification of susceptibility genes (genes that indicate an individual's increased risk for developing eating disorders) that will help to develop more effective treatments for these disorders. Other research is investigating the relationship between brain functions and emotional and social behavior related to eating disorders and the role of the brain in feeding behavior. Scientists have learned that both appetite and energy expenditure are regulated by a highly complex network of nerve cells and intercellular messengers called neuropeptides. The role of sex hormones, known as gonadal steroids, in the development of eating disorders is suggested by gender as a risk for these disorders. For example, the start of eating disorders at puberty or soon after, and the increased risk for eating disorders among girls who begin to menstruate early. These discoveries provide insight into the biochemical mechanisms of eating disorders and offer potential direction for the development of new drugs and treatments for these disorders.
In "A Review and Primer of Molecular Genetic Studies of Anorexia Nervosa" (International Journal of Eating Disorders, vol. 37, supplement, July 2005), authors Kelly Klump and Kyle Gobrogge summarized recent findings about the genetic underpinnings of eating disorders. They reported that research reveals some role for the brain system that involves the chemical serotonin in the development of anorexia nervosa; serotonin is a neurotransmitter involved in the regulation of mood and certain mental disorders, such as depression and anxiety. Genomic regions on chromosomes 1 and 10 are likely to harbor susceptibility genes for anorexia as well as other eating disorders. The findings from these genetic studies support those of neurobiologic studies indicating that alterations in serotonin functioning may contribute to the development of eating disorders.
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