Mostly confined to women, 5% of sufferers are male. Most patients are in their 20’s. the self induced vomiting can produce medical side effects e.g. enamel erosion changes level of potassium and sodium in the bodily fluids. These changes can be life threatening
There is overlap between the two disorders but there are important distinctions such as the tendency of anorexics to strive for perfection, but bulimics are trying to satisfy a constant craving. BN is more common than AN in western society. AN sufferers are within 10% of their normal weight BN sufferers it is 15%.
The way that the models explain AN and BN
Biological
Infection Park et al-it is possible that physical illness can act as a precipitating factor in eating disorders. Glandular fever may have an effect on the hypothalamus which would cause homeostatic in-balance
Genetic factors Holland et al-relatives of patients with eating disorders are 5 times more likely to develop the disease
Twin studies have been very useful.
Monozygotic twins (MZ) share exactly the same genes. Dizygotic (DZ) have the same genetic relatedness of normal siblings.
More MZ twins both develop AN than DZ twins, In BN there is not much difference.
But because not all MZ twins both got the disease this suggests that it is not soley dues to genetics, but maybe there is a genetic vunerability.
Neuroanatomy
The individual may have brain abnormalities for example in the hypothalamus.
But this could be caused by the disorder, rather than the cause OF it.
Psychodynamic
Sexual development-The fact that the disorder starts in teenage girls suggests that AN is related to sexual fears such as fear of getting pregnant leads to not wanting to have periods and a desire to remain pre-pubescent
Family systems Rosenman et al- the family of an anorexic is characterised by enmeshment meaning that none of the family members have a clear identity because everything is done together, refusing to eat is a rebellion.
This doesn’t explain why more girls suffer than boys.
Autonomy struggle bruch- patients with anorexia are often engaged in a struggle for their own sense of identity and autonomy and are in conflict with their parents. Also food may have been used as a punishment for example ‘if you don’t do this you get no desert’ and so is a currency for affection.
Behavioural
Conditioning theory Thompson et al
Using the principle of classical conditioning 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.
It can also be explained in terms of operant conditioning, Food avoidance can be rewarding and reinforcing it is a good way of getting attention.
Someone begins to lose weight, receives praise for it which reinforces them. Individual feels good and wants to lose more weight so loss of weight becomes associated with attention from others and feeling good.
the treatment for this, rewarding weight gain to try and un-condition patients has proved effective but this does not take into account genetic vunerability
Modelling Cooper et al
Anorexia is more common in western society, this can be explain in terms of role models available most of them emphasise slimness and we are likely to imitate them.
Nasser-studies Egyptian women studying in Cairo and London none of the women studying in Cairo developed an eating disorder in contrast to 12% of those studying in London.
This explains many features of the disorders and also backs up genetic vulnerability but the majority of women didn’t develop a disorder so cultural factors alone cannot be responsible.
Cognitive approach
Distortion of Body image
Sufferers of eating disorders have distorted views of their own body weight and shape. These are known as cognitive biases.
Garfinkel and Garner found that anorexics typically over estimate their body size when exposed to an image distorting technique compared to that of controls.
It is unclear weather these cognitive biases happen after the eating disorder starts or before.
