anorexia nervosa anorexia nervosa anorexia nervosa, often referred to simply as anorexia, is an eating disorder characterized by low weight, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin. anorexia is a term of greek origin: an- (ἀν-, prefix denoting negation) and orexis (ὄρεξις, "appetite"), translating literally to "a loss of appetite"; the adjective nervosa indicating the functional and non-organic nature of the disorder. anorexia nervosa was coined by gull in 1873 but, despite literal translation, the feeling of hunger is frequently present and the pathological control of this instinct is a source of satisfaction for the patients. "anorexia" and "anorexic" redirect here. for lack of appetite, see anorexia (symptom). for the medication, see anorectic. for other uses, see anorexia (disambiguation). anorexia nervosaother namesanorexia"miss a—" depicted in 1866 and in 1870 after treatment. her condition was one of the earliest case studies of anorexia, published in medical research papers of william gull.specialtypsychiatry, clinical psychologysymptomslow weight, fear of gaining weight, strong desire to be thin, food restrictions, body image disturbancecomplicationsosteoporosis, infertility, heart damage, suicide whole-body swelling (edema), heart failure and/or lung failure, gastrointestinal problems, extensive muscle weakness, delirium, death.usual onsetteen years to young adulthoodcausesunknownrisk factorsfamily history, high-level athletics, modelling, substance use disorder, dancingdifferential diagnosisbody dysmorphic disorder, bulimia nervosa, hyperthyroidism, inflammatory bowel disease, dysphagia, cancertreatmentcognitive behavioral therapy, hospitalisation to restore weightprognosis5% risk of death over 10 yearsfrequency2.9 million (2015)deaths600 (2015) individuals with anorexia nervosa have a fear of being overweight or being seen as such, although they are in fact underweight. the dsm-5 describes this perceptual symptom as "disturbance in the way in which one's body weight or shape is experienced". in research and clinical settings, this symptom is called "body image disturbance". individuals with anorexia nervosa also often deny that they have a problem with low weight. they may weigh themselves frequently, eat small amounts, and only eat certain foods. some exercise excessively, force themselves to vomit (in the "anorexia purging" subtype), or use laxatives to lose weight and control body shapes, and/or binge eat. medical complications may include osteoporosis, infertility, and heart damage, along with the cessation of menstrual periods. in extreme cases, patients with anorexia nervosa who continually refuse significant dietary intake and weight restoration interventions, and are declared incompetent to make decisions by a psychiatrist, may be fed by force under restraint via nasogastric tube after asking their parents or proxies to make the decision for them. the cause of anorexia is currently unknown. there appear to be some genetic components with identical twins more often affected than fraternal twins. cultural factors also appear to play a role, with societies that value thinness having higher rates of the disease. additionally, it occurs more commonly among those involved in activities that value thinness, such as high-level athletics, modeling, and dancing. anorexia often begins following a major life-change or stress-inducing event. the diagnosis requires a significantly low weight and the severity of disease is based on body mass index (bmi) in adults with mild disease having a bmi of greater than 17, moderate a bmi of 16 to 17, severe a bmi of 15 to 16, and extreme a bmi less than 15. in children, a bmi for age percentile of less than the 5th percentile is often used. treatment of anorexia involves restoring the patient back to a healthy weight, treating their underlying psychological problems, and addressing behaviors that promote the problem. while medications do not help with weight gain, they may be used to help with associated anxiety or depression. different therapy methods may be useful, such as cognitive behavioral therapy or an approach where parents assume responsibility for feeding their child, known as maudsley family therapy. sometimes people require admission to a hospital to restore weight. evidence for benefit from nasogastric tube feeding is unclear; such an intervention may be highly distressing for both anorexia patients and healthcare staff when administered against the patient's will under restraint. some people with anorexia will have a single episode and recover while others may have recurring episodes over years. many complications improve or resolve with the regaining of weight. globally, anorexia is estimated to affect 2.9 million people as of 2015. it is estimated to occur in 0.3% to 4.3% of women and 0.2% to 1% of men in western countries at some point in their life. about 0.4% of young women are affected in a given year and it is estimated to occur ten times more commonly among women than men. rates in most of the developing world are unclear. often it begins during the teen years or young adulthood. while anorexia became more commonly diagnosed during the 20th century, it is unclear if this was due to an increase in its frequency or simply better diagnosis. in 2013, it directly resulted in about 600 deaths globally, up from 400 deaths in 1990. eating disorders also increase a person's risk of death from a wide range of other causes, including suicide. about 5% of people with anorexia die from complications over a ten-year period, a nearly six times increased risk. according to a study conducted in 2020, it was observed that the unadjusted odds ratio of mortality among male (6.1%) patients was more than twice the ratio for female patients (2.6%) in japan (edakubo & fushimi). in recent years, evolutionary psychiatry as an emerging scientific discipline has been studying mental disorders from an evolutionary perspective. it is still debated whether eating disorders such as anorexia have evolutionary functions or if they are problems resulting from a modern lifestyle. signs and symptoms the back of a person with anorexia anorexia nervosa is an eating disorder characterized by attempts to lose weight to the point of starvation. a person with anorexia nervosa may exhibit a number of signs and symptoms, the type and severity of which may vary and be present but not readily apparent. anorexia nervosa, and the associated malnutrition that results from self-imposed starvation, can cause complications in every major organ system in the body. hypokalaemia, a drop in the level of potassium in the blood, is a sign of anorexia nervosa. a significant drop in potassium can cause abnormal heart rhythms, constipation, fatigue, muscle damage, and paralysis. signs and symptoms may be classified in physical, cognitive, affective, behavioral and perceptual: physical symptoms a low body mass index for one's age and height amenorrhea, a symptom that occurs after prolonged weight loss, causing menstruation to change drastically or to stop all together dry hair and skin, as well as hair thinning fear of even the slightest weight gain; taking all precautionary measures to avoid weight gain or becoming "overweight" rapid, continuous weight loss lanugo: soft, fine hair growing over the face and body bradycardia or tachycardia. chronic fatigue orange discoloration of the skin, particularly the feet (carotenosis) infertility halitosis (from vomiting or starvation-induced ketosis) hypotension or orthostatic hypotension having severe muscle tension, aches and pains insomnia abdominal distension cognitive symptoms an obsession with counting calories and monitoring fat contents of food. preoccupation with food, recipes, or cooking; may cook elaborate dinners for others, but not eat the food themselves or consume a very small portion. admiration of thinner people. thoughts of being fat or not thin enough an altered mental representation of one's body impaired theory of mind, exacerbated by lower bmi and depression difficulty in abstract thinking and problem solving rigid and inflexible thinking poor self-esteem hypercriticism and perfectionism affective symptoms depression ashamed of oneself or one's body anxiety disorders rapid mood swings emotional dysregulation alexithymia behavioral symptoms food / energy restrictions despite being underweight or at a healthy weight. food rituals, such as cutting food into tiny pieces, refusing to eat around others, and hiding or discarding of food. purging (only in the anorexia purging subtype) with laxatives, diet pills, ipecac syrup or diuretics to flush food out of their system after eating or engage in self-induced vomiting. anorexia purging is a subtype of anorexia, where in the person severely restricts most of the time but has reoccurring episodes of binge eating. after bingeing they engage in purging behaviors. this is different from bulimia nervosa. excessive exercise, including micro-exercising, for example making small persistent movements of fingers or toes. self harming or self-loathing. solitude: may avoid friends and family and become more withdrawn and secretive. perceptual symptoms perception of self as overweight, in contradiction to an underweight reality (namely "body image disturbance") intolerance to cold and frequent complaints of being cold; body temperature may lower (hypothermia) in an effort to conserve energy due to malnutrition. altered body schema (i.e. an implicit representation of the body evoked by acting) altered interoception interoception interoception involves the conscious and unconscious sense of the internal state of the body, and it has an important role in homeostasis and regulation of emotions. aside from noticeable physiological dysfunction, interoceptive deficits also prompt individuals with anorexia to concentrate on distorted perceptions of multiple elements of their body image. this exists in both people with anorexia and in healthy individuals due to impairment in interoceptive sensitivity and interoceptive awareness. aside from weight gain and outer appearance, people with anorexia also report abnormal bodily functions such as indistinct feelings of fullness. this provides an example of miscommunication between internal signals of the body and the brain. due to impaired interoceptive sensitivity, powerful cues of fullness may be detected prematurely in highly sensitive individuals, which can result in decreased calorie consumption and generate anxiety surrounding food intake in anorexia patients. people with anorexia also report difficulty identifying and describing their emotional feelings and the inability to distinguish emotions from bodily sensations in general, called alexithymia. interoceptive awareness and emotion are deeply intertwined, and could mutually impact each other in abnormalities. anorexia patients also exhibit emotional regulation difficulties that ignite emotionally-cued eating behaviors, such as restricting food or excessive exercising. impaired interoceptive sensitivity and interoceptive awareness can lead anorexia patients to adapt distorted interpretations of weight gain that are cued by physical sensations related to digestion (e.g., fullness). combined, these interoceptive and emotional elements could together trigger maladaptive and negatively reinforced behavioral responses that assist in the maintenance of anorexia. in addition to metacognition, people with anorexia also have difficulty with social cognition including interpreting others' emotions, and demonstrating empathy. abnormal interoceptive awareness and interoceptive sensitivity shown through all of these examples have been observed so frequently in anorexia that they have become key characteristics of the illness. comorbidity other psychological issues may factor into anorexia nervosa. some people have a previous disorder which may increase their vulnerability to developing an eating disorder and some develop them afterwards. the presence of psychiatric comorbidity has been shown to affect the severity and type of anorexia nervosa symptoms in both adolescents and adults. obsessive-compulsive disorder (ocd) and obsessive-compulsive personality disorder (ocpd) are highly comorbid with an. ocd is linked with more severe symptomatology and worse prognosis. the causality between personality disorders and eating disorders has yet to be fully established. other comorbid conditions include depression, alcoholism, borderline and other personality disorders, anxiety disorders, attention deficit hyperactivity disorder, and body dysmorphic disorder (bdd). depression and anxiety are the most common comorbidities, and depression is associated with a worse outcome. autism spectrum disorders occur more commonly among people with eating disorders than in the general population. zucker et al. (2007) proposed that conditions on the autism spectrum make up the cognitive endophenotype underlying anorexia nervosa and appealed for increased interdisciplinary collaboration. causes dysregulation of the serotonin pathways has been implicated in the cause and mechanism of anorexia. there is evidence for biological, psychological, developmental, and sociocultural risk factors, but the exact cause of eating disorders is unknown. genetic genetic correlations of anorexia with psychiatric and metabolic traits anorexia nervosa is highly heritable. twin studies have shown a heritability rate of 28–58%. first-degree relatives of those with anorexia have roughly 12 times the risk of developing anorexia. association studies have been performed, studying 128 different polymorphisms related to 43 genes including genes involved in regulation of eating behavior, motivation and reward mechanics, personality traits and emotion. consistent associations have been identified for polymorphisms associated with agouti-related peptide, brain derived neurotrophic factor, catechol-o-methyl transferase, sk3 and opioid receptor delta-1. epigenetic modifications, such as dna methylation, may contribute to the development or maintenance of anorexia nervosa,