Anorexia nervosa is an eating disorder characterised by he individual being severely underweight. The biological approach states that the causes of anorexia resemble those of physical illnesses, and there is some evidence that infection, genetic factors, biochemistry or neuroatomy may account fro anorexia. It also assumes that symptoms can be described, leading to the diagnosis of anorexia. So if someone had amenorrhoea, a body image distortion, and was severely underweight you could classify them as anorexic.
It is possible that physical illness may act as a precipitating factor in anorexia nervosa. Park, Lawrie, and Freeman studied four females suffering from anorexia, all of whom had had glandular fever or a similar disease shortly before the onset of the eating disorder, however this is only a small sample, so the evidence is not sufficient. There is also a lot of evidence that genetic factors play a part in the development of anorexia. Holland et al examined the genetic basis of anorexia, by investigating whether there was a higher concordance rate of anorexia for monozygotic or dizygotic twins. He studied 34 twins, where one member would have the disorder, and found that 56% of the MZ twins were concordant for anorexia, whereas only 6% of the DZ pairs were concordant.
These results suggests that there is some genetic involvement in anorexia, but it is not solely genetic, otherwise 100% of MZ twins would have developed anorexia. It may be that genes predispose individuals to develop the disorder, creating a genetic vulnerability, as suggested by the diathesis-stress model. However this study lacks control of the variables, and ignores the role of the environmental factors. It is also limited as it was carried out in a western society, where anorexia is much more common.
However another idea of the biological approach is that anorexia develops from neuroanatomy, where there is brain abnormality. E.g. The parts of hypothalamus that control eating, sexual activity and menstruation may function abnormally in anorexics. Yet, the same problem arises as to whether altered hypothalamic activity is a cause of anorexia, or a result of anorexia. However Hilda Brach would argued that anorexia is related to mother-daughter conflicts over dominance and autonomy.
However these explanations tend to lack objectivity and cannot explain recent increase in anorexia. As branches work was done on case studies alone, there is no scientific evidence to fully support her work. The psychological approach is driven by conflict between the id and the superego, so the ego resorts to defence mechanisms. One possibility is that anorexia acts as a means of avoiding sexual maturity. Minuchin’s family system theory suggests that anorexia develops as a result of enmeshed family dynamics.
Alternatively there is the behaviourist view, which outlines anorexia as the result of both conditioning, both classical and operant. The social learning theory. Lee et al investigated the social learning theory. He suggested Western woman experience role conflicts between home and career, and their inner and outer selves. This may result in low self esteem and ambivalence towards oneself. Chinese women live in a society where their success is more related to ‘traditional’ values such as success with the family rather than a good personal appearance.
This is one important social and cultural factor as to why anorexia develops strongly in western societies, but it cannot explain why not all women develop anorexia. According to Leitenberg, Agras, and Thomson anorexics may have learned to associate eating with anxiety, because eating too much makes people overweight and unattractive. Therefore they seek to lose weight to reduce their anxiety. However conditioning alone does not account for individual differences in vulnerability to eating disorders.
Alternatively there is the cognitive approach, where anorexics have distorted views about their body shape and weight. They overestimate their size, and they have a tendency towards perfection. Fallon and Rozin asked males and females to indicate their ideal body size and the body size that would be attractive to the opposite sex. Females rated their body weight as significantly lower than the weight males thought most attractive, whereas males rated their ideal body weight as higher than the weight woman found most attractive.
However it is unclear weather these cognitive biases exist before the onset of anorexia, or whether they only develop afterwards Anorexia fits into the diathesis-stress model, which states that anorexia nervosa depends both on 1) diathesis, a genetic vulnerability to the disorder, and 2)on stress, when there is some disturbing environmental event. This is because each model is partially correct on the origins of anorexia, so we combine all the information from all the models.