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Anorexia nervosa is a psychiatric diagnosis that describes an eating disorder characterized by low body weight and body image distortion with an obsessive fear of gaining weight. Individuals with anorexia often control body weight by voluntary starvation, purging, vomiting, excessive exercise, or other weight control measures, such as diet pills or diuretic drugs. It primarily affects adolescent females, however approximately 10% of people with the diagnosis are male. Anorexia nervosa is a complex condition, involving psychological, neurobiological, and sociological components.
The term anorexia is of Greek origin: an (privation or lack of) and orexis (appetite) thus meaning a lack of desire to eat. A person who is diagnosed with anorexia nervosa is most commonly referred to with the adjectival form anorexic. The noun form, "anorectic" is generally not used in this context and usually refers to drugs that suppress appetite.
"Anorexia nervosa" is frequently shortened to "anorexia" in both the popular media and scientific literature. This is technically incorrect, as the term "anorexia" used separately refers to the medical symptom of reduced appetite.
Additional recommended knowledge
Diagnosis and clinical features
The most commonly used criteria for diagnosing anorexia are from the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) and the World Health Organization's International Statistical Classification of Diseases and Related Health Problems (ICD).
Although biological tests can aid the diagnosis of anorexia, the diagnosis is based on a combination of behavior, reported beliefs and experiences, and physical characteristics of the patient. Anorexia is typically diagnosed by a clinical psychologist, psychiatrist or other suitably qualified clinician.
Notably, diagnostic criteria are intended to assist clinicians, and are not intended to be representative of what an individual sufferer feels or experiences in living with the illness.
The full ICD-10 diagnostic criteria for anorexia nervosa can be found here, and the DSM-IV-TR criteria can be found here.
To be diagnosed as having anorexia nervosa, according to the DSM-IV-TR, a person must display:
Furthermore, the DSM-IV-TR specifies two subtypes:
The ICD-10 criteria are similar, but in addition, specifically mention
Anorexia nervosa can put a serious strain on many of the body's organs and physiological resources,  particularly on the structure and function of the heart and cardiovascular system, with slow heart rate (bradycardia) and elongation of the QT interval seen early on. People with anorexia typically have a disturbed electrolyte balance, particularly low levels of phosphate, which has been linked to heart failure, muscle weakness, immune dysfunction, and ultimately death. Those who develop anorexia before adulthood may suffer stunted growth and subsequent low levels of essential hormones (including sex hormones) and chronically increased cortisol levels. Osteoporosis can also develop as a result of anorexia in 38-50% of cases, as poor nutrition leads to the retarded growth of essential bone structure and low bone mineral density. Anorexia does not harm everyone in the same way. For example, evidence suggests that the results of the disease in adolescents may differ from those in adults.
Changes in brain structure and function are early signs of the condition. Enlargement of the ventricles of the brain is thought to be associated with starvation, and is partially reversed when normal weight is regained. Anorexia is also linked to reduced blood flow in the temporal lobes, although since this finding does not correlate with current weight, it is possible that it is a risk trait rather than an effect of starvation.
Other effects may include the following:
Interpersonal and social
Diagnostic issues and controversies
The distinction between the diagnoses of anorexia nervosa, bulimia nervosa and eating disorder not otherwise specified (EDNOS) is often difficult to make in practice and there is considerable overlap between patients diagnosed with these conditions. Furthermore, seemingly minor changes in a patient's overall behavior or attitude (such as reported feeling of 'control' over any bingeing behavior) can change a diagnosis from 'anorexia: binge-eating type' to bulimia nervosa. It is not unusual for a person with an eating disorder to 'move through' various diagnoses as his or her behavior and beliefs change over time.
Additionally, it is important to note that an individual may still suffer from a health- or life-threatening eating disorder (e.g., sub-clinical anorexia nervosa or EDNOS) even if one diagnostic sign or symptom is still present. For example, a substantial number of patients diagnosed with EDNOS meet all criteria for diagnosis of anorexia nervosa, but lack the three consecutive missed menstrual cycles needed for a diagnosis of anorexia.
Feminist writers such as Susie Orbach and Naomi Wolf have criticized the medicalisation of extreme dieting and weight-loss as locating the problem within the affected women, rather than in a society that imposes concepts of unreasonable and unhealthy thinness as a measure of female beauty.
Causes and contributory factors
It is clear that there is no single cause for anorexia and that it stems from a mixture of social, psychological and biological factors. Current research is commonly focused on explaining existing factors and uncovering new causes. However, there is considerable debate over how much each of the known causes contributes to the development of anorexia. In particular, the contribution of perceived media pressure on women to be thin has been especially contentious.
Family and twin studies have suggested that genetic factors contribute to about 50% of the variance for the development of an eating disorder and that anorexia shares a genetic risk with clinical depression. This evidence suggests that genes influencing both eating regulation, and personality and emotion, may be important contributing factors.
Several rodent models of anorexia have been developed which largely involve subjecting the animals to various environmental stressors or using gene knockout mice to test hypotheses about the effects of certain genes on related behavior. These models have suggested that the hypothalamic-pituitary-adrenal axis may be a contributory factor, although the models have been criticised as food is being limited by the experimenter and not the animal, and these models cannot take into account the complex cultural factors known to affect the development of anorexia nervosa.
There are strong correlations between the neurotransmitter serotonin and various psychological symptoms such as mood, sleep, emesis (vomiting), sexuality and appetite. A recent review of the scientific literature has suggested that anorexia is linked to a disturbed serotonin system, particularly to high levels at areas in the brain with the 5HT1A receptor - a system particularly linked to anxiety, mood and impulse control. Starvation has been hypothesised to be a response to these effects, as it is known to lower tryptophan and steroid hormone metabolism, which, in turn, might reduce serotonin levels at these critical sites and, hence, ward off anxiety. In contrast, studies of the 5HT2A serotonin receptor (linked to regulation of feeding, mood, and anxiety), suggest that serotonin activity is decreased at these sites. One difficulty with this work, however, is that it is sometimes difficult to separate cause and effect, in that these disturbances to brain neurochemistry may be as much the result of starvation, than continuously existing traits that might predispose someone to develop anorexia. There is evidence, however, that both personality characteristics (such as anxiety and perfectionism) and disturbances to the serotonin system are still apparent after patients have recovered from anorexia, suggesting that these disturbances are likely to be causal risk factors.
Zinc deficiency causes a decrease in appetite that can degenerate in anorexia nervosa (AN), appetite disorders and, notably, inadequate zinc nutriture. The use of zinc in the treatment of anorexia nervosa has been advocated since 1979 by Bakan. At least five trials showed that zinc improved weight gain in anorexia. A 1994 randomized, double-blind, placebo-controlled trial showed that zinc (14 mg per day) doubled the rate of body mass increase in the treatment of AN. Deficiency of other nutrients such as tyrosine and tryptophan (precursors of the monoamine neurotransmitters norepinephrine and serotonin, respectively), as well as vitamin B1 (thiamine) could contribute to this phenomenon of malnutrition-induced malnutrition.
There has been a significant amount of work into psychological factors that suggests how biases in thinking and perception help maintain or contribute to the risk of developing anorexia.
Anorexic eating behavior is thought to originate from feelings of fatness and unattractiveness and is maintained by various cognitive biases that alter how the affected individual evaluates and thinks about their body, food and eating.
One of the most well-known findings is that people with anorexia tend to over-estimate the size or fatness of their own bodies. A recent review of research in this area suggests that this is not a perceptual problem, but one of how the perceptual information is evaluated by the affected person. Recent research suggests people with anorexia nervosa may lack a type of overconfidence bias in which the majority of people feel themselves more attractive than others would rate them. In contrast, people with anorexia nervosa seem to more accurately judge their own attractiveness compared to unaffected people, meaning that they potentially lack this self-esteem boosting bias.
People with anorexia have been found to have certain personality traits that are thought to predispose them to develop eating disorders. High levels of obsessionality (being subject to intrusive thoughts about food and weight-related issues), restraint (being able to fight temptation), and clinical levels of perfectionism (the pathological pursuit of personal high-standards and the need for control) have been cited as commonly reported factors in research studies.
It is often the case that other psychological difficulties and mental illnesses exist alongside anorexia nervosa in the sufferer. Clinical depression, obsessive compulsive disorder, substance abuse and one or more personality disorders are the most likely conditions to be comorbid with anorexia, and high-levels of anxiety and depression are likely to be present regardless of whether they fulfill diagnostic criteria for a specific syndrome.
Research into the neuropsychology of anorexia has indicated that many of the findings are inconsistent across studies and that it is hard to differentiate the effects of starvation on the brain from any long-standing characteristics. Nevertheless, one reasonably reliable finding is that those with anorexia have poor cognitive flexibility (the ability to change past patterns of thinking, particularly linked to the function of the frontal lobes and executive system).
Other studies have suggested that there are some attention and memory biases that may maintain anorexia. Attentional biases seem to focus particularly on body and body-shape related concepts, making them more salient for those affected by the condition, and some limited studies have found that those with anorexia may be more likely to recall related material than unrelated material.
Although there has been quite a lot of research into psychological factors, there are relatively few hypotheses which attempt to explain the condition as a whole.
Professor Chris Fairburn, of the University of Oxford and his colleges have created a 'transdiagnostic' model, in which they aim to explain how anorexia, as well as related disorders such as bulimia nervosa and ED-NOS, are maintained. Their model is developed with psychological therapies, particularly cognitive behavioral therapy, in mind, and so suggests areas where clinicians could provide psychological treatment.
Their model is based on the idea that all major eating disorders (with the exception of obesity) share some core types of psychopathology which help maintain the eating disorder behavior. This includes clinical perfectionism, chronic low self-esteem, mood intolerance (inability to cope appropriately with certain emotional states) and interpersonal difficulties.
Social and environmental factors
Sociocultural studies have highlighted the role of cultural factors, such as the promotion of thinness as the ideal female form in Western industrialised nations, particularly through the media. A recent epidemiological study of 989,871 Swedish residents indicated that gender, ethnicity and socio-economic status were large influences on the chance of developing anorexia, with those with non-European parents among the least likely to be diagnosed with the condition, and those in wealthy, white families being most at risk. A classic study by Garner and Garfinkel demonstrated that those in professions where there is a particular social pressure to be thin (such as models and dancers) were much more likely to develop anorexia during the course of their career, and further research has suggested that those with anorexia have much higher contact with cultural sources that promote weight-loss.
Although anorexia nervosa is usually associated with Western cultures, exposure to Western media is thought to have led to an increase in cases in non-Western countries. However, it is notable that other cultures may not display the same 'fat phobic' worries about becoming fat as those with the condition in the West, and instead may present with low appetite with the other common features.
There is a high rate of child sexual abuse experiences in those who have been diagnosed with anorexia (up to 50% in those admitted to inpatient wards, with a lesser prevalence among people treated in the community). Although prior sexual abuse is not thought to be a specific risk factor for anorexia (although it is a risk factor of mental illness in general), those who have experienced such abuse are more likely to have more serious and chronic symptoms.
The Internet has enabled anorexics and bulimics to contact and communicate with each other outside of a treatment environment, with much lower risks of rejection by mainstream society. A variety of websites exist, some run by sufferers, some by former sufferers, and some by professionals. The majority of such sites support a medical view of anorexia as a disorder to be cured, although some people affected by anorexia have formed online pro-ana communities that reject the medical view and argue that anorexia is a 'lifestyle choice', using the internet for mutual support, and to swap weight-loss tips. Such websites were the subject of significant media interest, largely focusing on concerns that these communities could encourage young women to develop or maintain eating disorders, and many were taken offline as a result.
Anorexia is thought to have the highest mortality rate of any psychiatric disorder, with approximately 10% of those who are diagnosed with the disorder eventually dying due to related causes. The suicide rate of people with anorexia is also higher than that of the general population and is thought to be the major cause of death for those with the condition. A recent review suggested that less than one-half recover fully, one-third improve, and 20% remain chronically ill.
Incidence, prevalence and demographics
The majority of research into the incidence and prevalence of anorexia has been done in Western industrialized countries, so results are generally not applicable outside these areas. However, recent reviews of studies on the epidemiology of anorexia have suggested an incidence of between 8 and 13 cases per 100,000 persons per year and an average prevalence of 0.3% using strict criteria for diagnosis. These studies also confirm the view that the condition largely affects young adolescent females, with females between 15 and 19 years old making up 40% of all cases. Furthermore, the majority of cases are unlikely to be in contact with mental health services. As a whole, about 90% of people with anorexia are female.
The first line treatment for anorexia is usually focused on immediate weight gain, especially with those who have particularly serious conditions that require hospitalization. In particularly serious cases, this may be done as an involuntary hospital treatment under mental health law, where such legislation exists. In the majority of cases, however, people with anorexia are treated as outpatients, with input from physicians, psychiatrists, clinical psychologists and other mental health professionals.
A recent clinical review has suggested that psychotherapy is an effective form of treatment and can lead to restoration of weight, return of menses among female patients, and improved psychological and social functioning when compared to simple support or education programmes. However, this review also noted that there are only a small number of randomised controlled trials on which to base this recommendation, and no specific type of psychotherapy seems to show any overall advantage when compared to other types. Family therapy has also been found to be an effective treatment for adolescents with anorexia and in particular, a method developed at the Maudsley Hospital is widely used and found to maintain improvement over time.
Drug treatments, such as SSRI or other antidepressant medication, have not been found to be generally effective for either treating anorexia, or preventing relapse although it has also been noted that there is a lack of adequate research in this area. It is common, however, for antidepressants to be prescribed, often with the intent of trying to treat the associated anxiety and depression.
Supplementation with 14mg/day of zinc is recommended as routine treatment for anorexia nervosa due to a study showing a doubling of weight regain after treatment with zinc was begun. The mechanism of action is hypothesized to be an increased effectiveness of neurotransmission in various parts of the brain, including the amygdala, after adequate zinc intake begins resulting in increased appetite.
There are various non-profit and community groups that offer support and advice to people who have anorexia or who care for someone who does. Several are listed in the links below and may provide useful information for those wanting more information or help on treatment and medical care.
Media stories and reports
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Anorexia_nervosa". A list of authors is available in Wikipedia.|