Anorexia Nervosa theories and treatments


Biological Explanations for Anorexia Nervosa (Genetic Factors)


·       Kipman: If genes are an explanation for Anorexia Nervosa then the frequency of the illness should be higher in the general population and identical twins should be more concordant for anorexia.

What genes are being implicated in Anorexia Nervosa?

·       Gu et al: found when 2 or more members of a family have restrictive anorexia nervosa that they have the common chromosome which is 1P (Family study)

·       Wade et al: found a link between temperament and anorexia, supports genetic basic and temperament is genetically controlled. Perfectionism and High need for control were linked to anorexia. Could be due to family experience but also genes.

·       Nisoli: Found the TaqA1 alleleis present in people suffering with anorexia nervosa as well as other psychopathologies such as alcohol and drug abuse.

·       Scott-Van Zeeland: He found a link between ESR2which has links with oestrogen levels and anorexia nervosa. This gene links with the idea that women are more prone to anorexia nervosa than men. Also, EPHX2 which has links to cholesterol and serotonin which has further links to anxiety and depression and anorexia nervosa.


Twin Studies and concordance rates:

·       Holland et al: found a significant difference between the concordance rates of MZ and DZ twins. MZ= 56% DZ= 7%

·       Fairburn et al: found concordance rates of 55% for MZ and 5% for DZ.

Adoption studies and heritability:

·       Klump: Only one study done in this area and looked at disordered eating symptoms and found heritability ranged between 59-82%and shared environmental factors didn’t contribute significantly.

·       Heritability estimate: a % that estimates the likelihood of getting a disorder due to genes.



·       Gu et al: Supports this theory as he found a link between the chromosome 1P and anorexia nervosa in families where 2 or more people had the illness.

·       Klump: Also supports this theory as found heritability ranged between 50%-82% and ruled out shared environmental factors had no significant contribute to the disorder.

·       Holland et al: Further supports this theory as MZ twins and a concordance rate of 56% and DZ twins had a concordance rate of 7% showing more likely to get anorexia nervosa if you are a monozygotic twin who share 100% of the same genes.

·       Scott-Van Zeeland: ESR2 linked to anorexia as well as oestrogen levels. And EPHX2 has links with cholesterol, serotonin which causes anxiety and depression and found in patients with anorexia nervosa.

·       Application: If genes are the cause of Anorexia nervosa then we can help treat patients with gene therapy.

·       High Reliability: As concordance rates were consistent across all twin studies.


·       Low Generalisability: The samples of these studies are small, especially twin studies as it is difficult to find twins where at least one twin has anorexia nervosa.

·       Poor


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