Eating disorders are serious mental illnesses that include potentially life-threatening behav-ioral, psychological, and physiological disturbances. Walsh and Fairburn define an eating disorder as "a persistent disturbance of eating behavior or behavior intended to control weight, which significantly impairs physical health or psychosocial functioning," and are not secondary to any recognized general medical or other psychiatric disorder (Walsh & Fairburn, 2002). While eating disorders are illnesses that primarily occur in parts of the world where food is plentiful, they have been reported on every continent, including in developing countries (Nobakht & Dezhkam, 2000; Pike & Mizushima, 2005). While more serious eating disorder cases, and those that present within geographic proximity to tertiary care medical centers, may be referred to specialists for management, most cases are initially identified, and frequently managed by pediatricians, internists, and other primary care clinicians. Eating disorders include anorexia nervosa (AN), bulimia nervosa (BN), and other conditions that in the current diagnostic system are categorized together as Eating Disorders Not Otherwise Specified (EDNOS). These EDNOS conditions include binge eating disorder (BED), night eating syndrome (NES), and sub-threshold syndromes in which some, but not all of the symptoms of the more formally defined eating disorders are present. This chapter will review the clinical manifestations, general epidemiology, and treatment options for the major eating disorders, including AN, BN, and BED.
Clinical features and epidemiology Anorexia nervosa (AN) is a serious psychiatric illness characterized by failure to maintain a minimally normal weight, intense fear of gaining weight or becoming fat, and preoccupations about body shape and weight. AN has a lifetime prevalence of approximately 0.5%-1% among women, and is estimated to aﬀect one-tenth as many men (Hoek & van Hoeken, 2003). The onset of AN typically occurs in middle to late adolescence, the disorder being significantly more common in industrialized societies such as the United States and Europe than non-Western countries (Cummins, Simmons, & Zane, 2005; Eddy, Hennessey, & Thompson-Brenner, 2007; Hoek & van Hoeken, 2003; Pike & Mizushima, 2005). While the disorder has gained more public attention in recent decades, some version of AN can actually be traced back to the seventeenth century (Bell, 1987; Pearce, 2004). The defining psychological feature of AN is the relentless pursuit of thinness, which is often manifested by extreme weight control behaviors such as caloric restriction and excessive exercise. Associated with this severe dietary restraint, nearly 50% of individuals with AN also eventually develop episodic "loss of control" eating—that is, the aversive feeling that one is unable to stop or resist eating (Wilson, Grilo, & Vitousek, 2007). In AN, these loss of control episodes may be subjective, including small amounts more than what the individual intended to eat, or objective binges, including irrefutably large amounts of food consumed with discrete periods of time. Regardless of episode size, loss of control episodes may trigger purging behaviors, including self-induced vomiting and the abuse of laxatives or diuretics. However, these compensatory behaviors also may occur in the absence of loss of control eating. As a result of these extreme weight control behaviors, patients with AN maintain a body weight well below that which is minimally medically acceptable. Despite their low weight, patients often experience their bodies, or certain parts of their bodies, as too fat. This intense dissatisfaction with body shape and weight fuels a vicious cycle of weight loss and abnormal eating behavior that it is extremely diﬃcult for individuals with AN to interrupt. The current edition of the Diagnostic Statistical Manual of Mental Disorders (DSM-IV) has characterized AN using criteria that include the maintenance of low weight, the presence of cognitive distortions about body shape and weight, and the presence of amenorrhea for post-menarcheal females. There are two sub-types: restricting type, characterized by those who maintain low weight without any binge eating or purging behaviors, and binge-eating/purging type, characterized by the presence of binge eating or purging behaviors (see Table 1). While no specific weight threshold is identified for the AN diagnosis, DSM-IV includes an example of < 85% of recommended weight for height, and National Institute for Health and Clinical Excellence (NICE) guidelines suggest that body mass index (BMI) < 17.5 kg/m2 may indicate the presence of AN (American Psychiatric Association, 1994). In an attempt to improve diagnostic accuracy and inclusivity, draft criteria for AN proposed for DSM-5 include several changes (American Psychiatric Association, 1994). For example, the proposed criteria for DSM-5 eliminate amenorrhea as a requirement for the AN diagnosis, as evidence suggests that menstruation, while a general indicator of nutritional status, does not provide meaningful clinical distinction among individuals with AN. Furthermore the amenorrhea criterion is not useful for important sub-groups of individuals with the disorder, such as women taking oral contraceptive pills, adolescent patients with primary amenorrhea, and men (Attia & Roberto, 2009). Individuals with AN, regardless of subtype, often suﬀer from numerous medical complications consistent with the hypometabolic and malnourished state, including bradycardia (sometimes with prolonged QTc interval), hypotension, hypothermia, and leukopenia (Attia, 2010). Common signs present in patients with AN include hair loss, the development of a downy hair growth on the face, neck and extremities (lanugo), salivary gland enlargement, indigestion, and constipation (Walsh, 2008). Electrolyte abnormalities, such as hypokalemia and hyponatremia, may also present, especially in individuals whose symptomatology includes vomiting or laxative abuse. Even in the presence of significant starvation, it is possible for individuals with AN to display normal laboratory values. Therefore, clinicians should not rely solely on laboratory results to assess acuity of illness. In addition to abnormal laboratory values, individuals with AN commonly display low levels of estrogen and testosterone. These hormonal changes often result in decreased libido, amenorrhea among females, and decreased bone density, eventually leading to potentially irreversible osteopenia and/or osteoporosis. Perhaps the most serious physiological change associated with AN is a prolonged QTc interval, which can lead to cardiac arrhythmia and/or sudden death. Table 1. Diagnostic Criteria for Anorexia Nervosa, DSM-IV (American Psychi-atric Association, 1994) A) 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).B) Intense fear of gaining weight or becoming fat, even though underweight.C) 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.D) In postmenarcheal females, amenorrhea, 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). Specify type:Restricting Type: during the current episode of AN, the person has not regularly engaged in binge-eating or purging behavior (i.e., self-induced vomiting or the misuse of laxatives, diuretics, or enemas).Binge-Eating/Purging Type: during the current episode of AN, the person has regularly engaged in binge-eating or purging behavior (i.e., self-induced vomiting or the misuse of laxatives, diuretics, or enemas). Psychological symptoms associated with AN include distractibility, agitation, and sleep disturbance, along with increased depression, anxiety, obsessionality, and compulsivity (Attia, 2010). In addition to these often transient symptoms thought to be associated with the state of nutritional compromise, many individuals with AN also suﬀer from comorbid psychiatric diagnoses. In a meta-analysis of the outcome of AN in the twentieth century, Steinhausen found that the majority of patients suﬀered from one or more additional mental illnesses at follow-up, most commonly anxiety and mood disorders, personality disorders, and obsessive-compulsive tendencies (Steinhausen, 2002). However, it is important for clinicians to bear in mind that many symptoms of these comorbid disorders are exacerbated by the underweight condition, and thus may improve or even remit completely with the restoration and maintenance of normal body weight. In fact, studies of starvation in the absence of AN have been useful in identifying the myriad of ways that psychological symptoms develop and worsen in the context of malnutrition (Keys, Brozek, Henschel, Mickelsen, & Taylor, 1950). Historically, it has been very diﬃcult to track the long-term outcome of AN for reasons including the lengthy course of the disorder and significant relapse rate among those who undergo acute weight restoration. The limited research that has examined longitudinal outcome of AN has revealed high relapse rates and only modest recovery rates. In a trichotomized system classifying outcome of illness into good, fair, and poor, 46.9% of patients reached full recovery from AN, 33.5% improved, and 20.8% displayed a chronic course of the disorder (Steinhausen, 2002). Patients with AN also displayed significant crossover to other eating disorders, most frequently BN and EDNOS (Walsh, 2008). Furthermore, the crude mortality rate amongst patients with AN has been estimated at 5.0% per decade of illness, a rate as high as that seen in any psychiatric illness (Sullivan, 1995). Among a large epidemiological sample of individuals with AN followed in Sweden, the overall mortality rate was 6.2%, with the most common causes of death for the sample being suicide, substance abuse, and eating disorder-related complications (Papadopoulos, Ekbom, Brandt, & Ekselius, 2009). While there are some limitations to the available data regarding longitudinal outcome in AN, there is strong empirically based consensus that AN is a serious mental illness associated with significant morbidity and mortality. 9.2 Etiology Just as it has been diﬃcult to track the long-term outcome of AN, the task of identifying the causal underpinnings of the disorder has proven to be equally challenging. The relatively low incidence and limited ethnic and gendered scope of the disorder, as well as the complicating medical and psychological consequences of semi-starvation, render AN a particularly diﬃcult disorder to study in a controlled setting (Walsh & Devlin, 1998). Eating disorders have been proven to be more prevalent in women than men. For example Striegel-Moore et al. (2009) examined 3,714 women and 1,808 men and found that men were more likely to overeat than women. They found that around 1 in 5 women versus 1 in 10 men check their body size "very often". While the prevalence of eating disorders in cultures that idealize thinness suggest that social environment may play a causal role the development of the disorder, striking patterns of biological and psychological abnormalities in patients with AN suggest that multiple other factors also contribute (Attia & Walsh, 2009). Research has provided significant evidence for the role of genetic factors in the etiology of AN (Wade, Tiggemann, Bulik, Fairburn, Wray, & Martin, 2008; Bulik, Sullivan, Carter, McIntosh, & Joyce, 1999). Though specific genes have not been identified, the incidence of AN is greater in families with one aﬀected member, and the disorder has higher rates of concordance in monozygotic than dizygotic twins. Heritable factors may also contribute to the development of AN more distally, through temperamental variables associated with the illness, such as perfectionism, obsessionality, compulsivity, and, particularly in the binge/purge subgroup, emotional lability (Walsh, 2008). In addition, numerous physiological disturbances, including abnormalities in the gastrointestinal tract and various hormonal and neurotransmitter systems, have been considered as possible risk factors for AN (Walsh & Devlin, 1998). Researchers have speculated that leptin, a hormone that regulates appetite and metabolism, may play a role in the perpetuation of the illness, as leptin levels are typically low in underweight individuals with AN (Grinspoon, Gulick, Askari, Landt, Lee, Anderson, Ma, Vignati, Bowsher, & Herzog, 1996). Increased serotonergic activity has also been implicated in various behavioral and psychological characteristics of AN, including reduced food intake, perfectionism, and rigidity. Such evidence suggests that premorbid disturbances in this neurotransmitter might be a risk factor in the development of AN (Kaye, 2008). However, the influence of nutritional status on physiological processes requires caution in the interpretation of changes identified in AN, as these disturbances may be secondary to semi-starvation rather than contributing factors to the disorder’s development (Walsh & Devlin, 1998). While specific causal factors have not been identified, investigators have made progress regarding some of the factors that may contribute to the perpetuation of the illness or the risk of relapse. Mayer et al. found that among inpatients who had fully restored their BMI to > 20kg/m2, those with a higher percentage of body fat were less likely to relapse in the year following hospitalization (Mayer, Roberto, Glasofer, Etu, Gallagher, Wang, Heymsfield, Pierson, Attia, & Devlin, 2007). Furthermore, Schebendach et al. examined patients’ food records obtained prior to hospital discharge and found that those whose diets had greater variety and higher energy density were more likely to have a good clinical outcome during the year following hospital discharge (Schebendach, Mayer, Devlin, Attia, Contento, Wolf, & Walsh, 2008). 9.3 Treatment of AN Despite the fact that AN is an old illness, eﬀective treatments continue to elude clinicians. Studies in this area are few, and none have identified clear empirical support for particular psychotherapeutic or pharmacologic treatments. In part, the challenges to treatment research in AN have resulted from features of the illness itself, including the low prevalence of AN in the general population, and the small percentage of individuals with AN who are treatment-seeking. These characteristics of AN make it diﬃcult to recruit and retain adequate numbers of subjects for clinical studies (Wilson et al. 2007). Additionally, the medical issues present in AN make management diﬃcult and expensive, further complicating eﬀorts to rigorously study psychiatric interventions for this disorder. Treatment has evolved using various settings, including outpatient, day treatment, and hospital-based programs. It is generally accepted that treatment for AN needs to emphasize weight restoration. Behavioral management programs, aimed at normalizing weight and eating behavior, reinforce healthy behaviors and overall clinical progress with the use of consistently applied contingencies. While it is always desirable to utilize the least restrictive treatment setting in order to facilitate recovery, structured treatment programs such as inpatient, residential, and partial hospital programs may be necessary when outpatient eﬀorts are unsuccessful or unavailable, or when medical or psychiatric status requires a higher level of care to assure safety. Inpatient treatment is often recommended for individuals who have rapidly lost a substantial amount of weight (usually defined by a weight below 75% ideal body weight for one’s height, or a BMI of 16.5kg/m2). Voluntary treatment is also highly preferable, but involuntary arrangements may, at times, be appropriate, especially when a patient’s weight falls into a medically dangerous range (Attia & Walsh, 2009). Treatment for AN should target full restoration of normal weight with associated resolution of physiological changes that may have developed in the context of acute starvation. Healthy weight ranges are usually defined as being at least 90% of weight recommended for given height, but should consider pre-illness weight and weights at which normal physiological functioning such as normal menstrual activity is known to occur (Attia & Walsh, 2009). Treatment plans may include specific behavioral expectations (e.g., eat 100% of food that is prescribed by a treatment program, utilize staﬀ observation and other treatment interventions aimed to help interrupt purging behaviors, achieve recommended weight gain, etc.). Failure to make clinical progress may be met with additional interventions aimed at increasing caloric intake and decreasing behaviors of illness. Examples of these interventions may include prescription of additional food or nutritional supplements, increase of supervision, and decrease of prescribed activity. Such interventions are not intended to be punishment for "bad behavior," but rather flexible changes to facilitate the ultimate goals of weight gain and recovery. In behavioral programs, patients are prescribed a diet of an adequate number of calories to achieve weight restoration. Approximately 3500 kcal over maintenance requirements are needed for every pound gained; therefore, sizeable numbers of calories are needed to achieve consistent weight gain. Treatment programs for AN diﬀer in prescription of nutritional plan. Programs that achieve the typical weight gain rates of 2-4 lbs/week generally prescribe 3500-4000 kcal/day to patients at the peak of their weight gain needs. However, calories are typically started at a lower level and increased in a step-wise fashion in order to avoid refeeding syndrome, a syndrome consisting of serious, potentially life-threatening medical symptoms that may occur as refeeding begins and limited nutrient stores are tapped for catabolic processes (Attia & Walsh, 2009). Symptoms of refeeding syndrome may include hypophosphatemia, hypomagnesemia, significant fluid retention (both peripheral and visceral including risk of congestive heart failure (Mehanna, Moledina, & Travis, 2008). Risk factors for the development of refeeding syndrome include seriously low weight (e.g., BMI < 16.5 kg/m2), recent precipitous weight loss, and metabolic disturbance upon presentation, including significant hypokalemia. It is recommended that physical status, including weight, presence of edema, and electrolyte levels be evaluated closely during the first two weeks of acute refeeding. The Columbia Center for Eating Disorders begins weight restoration treatment with a caloric prescription of 1800 kcal/day. Pending medical stability (generally determined within the first week of hospitalization), the daily diet is increased by 400 kcal every 2 to 3 days until it reaches 3800 kcal, 3000 kcal of which are provided in solid food and the remaining 800 kcal of which are provided in liquid supplement. Because a large part of treating AN emphasizes restoring not only weight, but normal eating behaviors, oral feedings are preferable to nasogastric ones whenever possible. However, this option may be considered for resistant patients, or those who do not enter treatment voluntarily. Patients in behavioral management programs are also oﬀered a variety of therapeutic interventions from a multidisciplinary team of clinicians, commonly composed of physicians, psychologists, nurses, nutritionists, clinical social workers, and occupational therapists (Attia & Walsh, 2009). Treatment is aimed at confronting disordered eating behaviors and "feared" foods, as well as practicing normal eating. Meal and post-meal supervision, food shopping and cooking groups, and outings to local restaurants may be included in treatment programs to help patients process normal food selection and behaviors around eating with support from staﬀ and peers. Additionally, patients generally participate in regular therapy and discharge planning sessions with psychologists, psychiatric residents, and social workers in individual, group, and family settings. Such structured and comprehensive behavioral programs are largely eﬀective in helping patients with AN to normalize weight. Yet additional outpatient treatment dedicated to relapse prevention is generally necessary in order to maintain healthy eating and weight. Specific outpatient psychotherapies have been examined in AN, and preliminary evidence supports one of these approaches—a family-based therapy (FBT) for adolescents with AN—as a potentially helpful intervention for outpatient weight restoration and maintenance. FBT, also called, the "Maudsley" method, named for an approach that was developed at London’s Maudsley Hospital, assigns parents the responsibility of refeeding their child, utilizing many of the same treatment principles and reinforcements of structured behavioral programs. For adults, however, results with FBT have been less successful (Lock, 2001; Russell, Szmukler, Dare, & Eisler, 1987). Cognitive behavioral therapy (CBT) has also been studied in outpatients with AN, with more mixed results than that shown for FBT. CBT for AN was first described by Garner, Vitousek, and Pike in 1982 (Garner, Vitousek, & Pike, 1997). The regimen shares many basic therapeutic strategies with Fairburn’s CBT model of BN (1985), but emphasizes the AN-specific issues of enhancing motivation, recognizing the problems associated with semi-starvation, and encouraging weight gain. In a small randomized controlled trial of 33 weight-restored women with AN, Pike et al. found CBT to be more helpful than nutritional counseling at preventing relapse (53% relapse among those receiving nutritional counseling versus 22% relapse among those receiving CBT) (Pike, Walsh, Vitousek, Wilson, & Bauer, 2003). However, a larger study using CBT together with fluoxetine vs. placebo for relapse prevention found that the entire sample had relapse rates of greater than 40% (Walsh et al. 2006). Additional studies have identified clinical improvement in those receiving CBT; however, it is unclear whether CBT fares any better than other specific psychotherapies for individuals with AN (McIntosh, Jordan, Carter, Luty, McKenzie, Bulik, Frampton, & Joyce, 2005; Ball & Mitchell, 2004; Channon, De Silva, Hemsley, & Perkins, 1989). Because individuals with AN commonly suﬀer from anxiety, depression, and obsessionality, medications that are generally helpful for these symptoms in other clinical populations have been studied in AN. Overall, results from these studies, most of which have examined antidepressant medications in small samples, have been disappointing (Attia & Schroeder, 2005). Preliminary evidence is more promising regarding the potential utility of olanzapine, an atypical antipsychotic medication, in the treatment of AN. Case reports, open treatment trials, and one small randomized controlled trial (Bissada, Tasca, Barber, & Bradwejn, 2008) suggest that olanzapine may help with both weight gain and alleviating psychological symptoms, namely obsessionality, for individuals with AN (McKnight & Park, 2010). The generally negative findings from studies of antidepressants in acute AN have led some to posit that the poor response to medication may result from the state of malnutrition and its influence on factors that aﬀect medication response, such as neurotransmitter activity. As a result, medication studies in acutely weight-restored individuals have been conducted in order to examine the possible utility of medication at preventing relapse. Unfortunately, these studies have also failed to identify an eﬀective pharmacologic treatment for AN. For example, a large, placebo-controlled medication trial conducted by Walsh et al. did not demonstrate any benefit from fluoxetine in the treatment of weight-restored patients with AN (Walsh et al. 2006). AN remains a challenging psychiatric condition for which a single clear, empirically-validated standard of care does not exist. There is no question, however, that weight restoration is an essential first step in treating this disorder, and that behavioral methods are often eﬀective in facilitating this process. Medications alone are used less frequently in the management of AN, but are commonly incorporated as part of a multimodal approach to taking care of patients with this complex disorder.