though clinical research in this area is in its infancy. a 2019 study found a genetic relationship with mental disorders, such as schizophrenia, obsessive–compulsive disorder, anxiety disorder and depression; and metabolic functioning with a negative correlation with fat mass, type 2 diabetes and leptin. one gene that has been linked to anorexia might be of particular interest. this gene codes for a protein called the estrogen related receptor alpha (erralpha). in some tissues, this gene alters the ability of estrogen and estrogen receptors to interact with dna and change the function of cells. since estrogen has potent effects upon appetite and feeding, any genetic abnormality in the estrogen signaling pathway could contribute to the symptoms of anorexia and explain why anorexia typically appears in young women just after the onset of puberty. environmental obstetric complications: prenatal and perinatal complications may factor into the development of anorexia nervosa, such as preterm birth, maternal anemia, diabetes mellitus, preeclampsia, placental infarction, and neonatal heart abnormalities. neonatal complications may also have an influence on harm avoidance, one of the personality traits associated with the development of an. neuroendocrine dysregulation: altered signalling of peptides that facilitate communication between the gut, brain and adipose tissue, such as ghrelin, leptin, neuropeptide y and orexin, may contribute to the pathogenesis of anorexia nervosa by disrupting regulation of hunger and satiety. gastrointestinal diseases: people with gastrointestinal disorders may be more at risk of developing disorders of eating practices than the general population, principally restrictive eating disturbances. an association of anorexia nervosa with celiac disease has been found. the role that gastrointestinal symptoms play in the development of eating disorders seems rather complex. some authors report that unresolved symptoms prior to gastrointestinal disease diagnosis may create a food aversion in these persons, causing alterations to their eating patterns. other authors report that greater symptoms throughout their diagnosis led to greater risk. it has been documented that some people with celiac disease, irritable bowel syndrome or inflammatory bowel disease who are not conscious about the importance of strictly following their diet, choose to consume their trigger foods to promote weight loss. on the other hand, individuals with good dietary management may develop anxiety, food aversion and eating disorders because of concerns around cross contamination of their foods. some authors suggest that medical professionals should evaluate the presence of an unrecognized celiac disease in all people with eating disorder, especially if they present any gastrointestinal symptom (such as decreased appetite, abdominal pain, bloating, distension, vomiting, diarrhea or constipation), weight loss, or growth failure; and also routinely ask celiac patients about weight or body shape concerns, dieting or vomiting for weight control, to evaluate the possible presence of eating disorders, especially in women. studies have hypothesized the continuance of disordered eating patterns may be epiphenomena of starvation. the results of the minnesota starvation experiment showed normal controls exhibit many of the behavioral patterns of an when subjected to starvation. this may be due to the numerous changes in the neuroendocrine system, which results in a self-perpetuating cycle. anorexia nervosa is more likely to occur in a person's pubertal years. some explanatory hypotheses for the rising prevalence of eating disorders in adolescence are "increase of adipose tissue in girls, hormonal changes of puberty, societal expectations of increased independence and autonomy that are particularly difficult for anorexic adolescents to meet; increased influence of the peer group and its values." psychological early theories of the cause of anorexia linked it to childhood sexual abuse or dysfunctional families; evidence is conflicting, and well-designed research is needed. the fear of food is known as sitiophobia or cibophobia, and is part of the differential diagnosis. other psychological causes of anorexia include low self-esteem, feeling like there is lack of control, depression, anxiety, and loneliness. people with anorexia are, in general, highly perfectionistic and most have obsessive compulsive personality traits which may facilitate sticking to a restricted diet. it has been suggested that patients with anorexia are rigid in their thought patterns, and place a high level of importance upon being thin. a risk factor for anorexia is trauma. although the prevalence rates vary greatly, between 37% and 100%, there appears to be a link between traumatic events and eating disorder diagnosis. approximately 72% of individuals with anorexia report experiencing a traumatic event prior to the onset of eating disorder symptoms, with binge-purge subtype reporting the highest rates. there are many traumatic events that may be risk factors for development of anorexia, the first identified traumatic event predicting anorexia was childhood sexual abuse. however, other traumatic events, such as physical and emotional abuse have also been found to be risk factors. interpersonal, as opposed to non-interpersonal trauma, has been seen as the most common type of traumatic event, which can encompass sexual, physical, and emotional abuse. individuals who experience repeated trauma, like those who experience trauma perpetrated by a caregiver or loved one, have increased symptom severity of anorexia and a greater prevalence of comorbid psychiatric diagnoses. in individuals with anorexia, the prevalence rates for those who also qualify for a ptsd diagnosis ranges from 4% to 52% in non-clinical samples to 10% to 47% in clinical samples. a complicated symptom profile develops when trauma and anorexia meld; the bodily experience of the individual is changed and intrusive thoughts and sensations may be experienced. traumatic events can lead to intrusive and obsessive thoughts, and the symptom of anorexia that has been most closely linked to a ptsd diagnosis is increased obsessive thoughts pertaining to food. similarly, impulsivity is linked to the purge and binge-purge subtypes of anorexia, trauma, and ptsd. emotional trauma (e.g., invalidation, chaotic family environment in childhood) may lead to difficulty with emotions, particularly the identification of and how physical sensations contribute to the emotional response. trauma and traumatic events can disturb an individual's sense of self and affect their ability to thrive, especially within their bodies. when trauma is perpetrated on an individual, it can lead to feelings of not being safe within their own body; that their body is for others to use and not theirs alone. individuals may experience a feeling of disconnection from their body after a traumatic experience, leading to a desire to distance themselves from the body. trauma overwhelms individuals emotionally, physically, and psychologically. both physical and sexual abuse can lead to an individual seeing their body as belonging to an "other" and not to the "self". individuals who feel as though they have no control over their bodies due to trauma may use food as a means of control because the choice to eat is an unmatched expression of control. by exerting control over food, individuals can choose when to eat and how much to eat. individuals, particularly children experiencing abuse, may feel a loss of control over their life, circumstances, and their own bodies. particularly sexual abuse, but also physical abuse, can make individuals feel that the body is not a safe place and an object over which another has control. starvation, in the case of anorexia, may also lead to reduction in the body as a sexual object, making starvation a solution. restriction may also be a means by which the pain an individual is experiencing can be communicated. sociological anorexia nervosa has been increasingly diagnosed since 1950; the increase has been linked to vulnerability and internalization of body ideals. people in professions where there is a particular social pressure to be thin (such as models and dancers) were more likely to develop anorexia, and those with anorexia have much higher contact with cultural sources that promote weight loss. this trend can also be observed for people who partake in certain sports, such as jockeys and wrestlers. there is a higher incidence and prevalence of anorexia nervosa in sports with an emphasis on aesthetics, where low body fat is advantageous, and sports in which one has to make weight for competition. family group dynamics can play a role in the cause of anorexia including negative expressed emotion in overprotective families where blame is frequently experienced among its members. when there is a constant pressure from people to be thin, teasing and bullying can cause low self-esteem and other psychological symptoms. media effects persistent exposure to media that present body ideals may constitute a risk factor for body dissatisfaction and anorexia nervosa. the cultural ideal for body shape for men versus women continues to favor slender women and athletic, v-shaped muscular men. a 2002 review found that, of the magazines most popular among people aged 18 to 24 years, those read by men, unlike those read by women, were more likely to feature ads and articles on shape than on diet. body dissatisfaction and internalization of body ideals are risk factors for anorexia nervosa that threaten the health of both male and female populations. another online aspect contributing to higher rates of eating disorders such as anorexia nervosa are websites and communities on social media that stress the importance of attainment of body ideals extol and promote anorexia nervosa through the use of religious metaphors, lifestyle descriptions, "thinspiration" or "fitspiration" (inspirational photo galleries and quotes that aim to serve as motivators for attainment of body ideals). pro-anorexia websites reinforce internalization of body ideals and the importance of their attainment. the media portray a false view of what people truly look like. in magazines and movies and even on billboards most of the actors/models are digitally altered in multiple ways. people then strive to look like these "perfect" role models when in reality they are not near perfection themselves. mechanisms evidence from physiological, pharmacological and neuroimaging studies suggest serotonin (also called 5-ht) may play a role in anorexia. while acutely ill, metabolic changes may produce a number of biological findings in people with anorexia that are not necessarily causative of the anorexic behavior. for example, abnormal hormonal responses to challenges with serotonergic agents have been observed during acute illness, but not recovery. nevertheless, increased cerebrospinal fluid concentrations of 5-hydroxyindoleacetic acid (a metabolite of serotonin), and changes in anorectic behavior in response to acute tryptophan depletion (tryptophan is a metabolic precursor to serotonin) support a role in anorexia. the activity of the 5-ht2a receptors has been reported to be lower in patients with anorexia in a number of cortical regions, evidenced by lower binding potential of this receptor as measured by pet or spect, independent of the state of illness. while these findings may be confounded by comorbid psychiatric disorders, taken as a whole they indicate serotonin in anorexia. these alterations in serotonin have been linked to traits characteristic of anorexia such as obsessiveness, anxiety, and appetite dysregulation. neuroimaging studies investigating the functional connectivity between brain regions have observed a number of alterations in networks related to cognitive control, introspection, and sensory function. alterations in networks related to the dorsal anterior cingulate cortex may be related to excessive cognitive control of eating related behaviors. similarly, altered somatosensory integration and introspection may relate to abnormal body image. a review of functional neuroimaging studies reported reduced activations in "bottom up" limbic region and increased activations in "top down" cortical regions which may play a role in restrictive eating. compared to controls, people who have recovered from anorexia show reduced activation in the reward system in response to food, and reduced correlation between self reported liking of a sugary drink and activity in the striatum and anterior cingulate cortex. increased binding potential of 11c radiolabelled raclopride in the striatum, interpreted as reflecting decreased endogenous dopamine due to competitive displacement, has also been observed. structural neuroimaging studies have found global reductions in both gray matter and white matter, as well as increased cerebrospinal fluid volumes. regional decreases in the left hypothalamus, left inferior parietal lobe, right lentiform nucleus and right caudate have also been reported in acutely ill patients. however, these alterations seem to be associated with acute malnutrition and largely reversible with weight restoration, at least in nonchronic cases in younger people. in contrast, some studies have reported increased orbitofrontal cortex volume in currently ill and in recovered patients, although findings are inconsistent. reduced white matter integrity in the fornix has also been reported. diagnosis a diagnostic assessment includes the person's current circumstances, biographical history, current symptoms, and family history. the assessment also includes a mental state examination, which is an assessment of