AQA A2 Psychology Unit 3 Eating Behaviour: Biological Explanations Of Anorexia Nervosa Notes

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A2 Psychology Unit 3 Eating Behaviour: Biological Explanations Of Anorexia Nervosa Notes

What You Need To Know:

  • Biological explanations, including neural, for one eating disorder: e.g. anorexia nervosa

Genetics:

Family studies

  • Studies have found higher rates of anorexia in people who have relatives with the disorder.
  • Lilenfield et al (1998) looked at the family history of 26 anorexics and found a family vulnerability.
  • Vulnerability does not necessarily mean full-blown anorexia. Relatives were seven to twelve times more likely to have `sub-threshold` forms (not quite anorexia).

Twins studies

  • Identical (MZ) twins share 100% of their genes, so shared eating disorders might be due to genes.

Holland et al (1988) - concordance rates in twins

Method: Concordance rates (extent to which twins share the same traits) were studied in 45 pairs of twins. At least one twin of each pair had been diagnosed as having anorexia nervosa - the study examined how often the other twin also suffered from the disorder.

Results: The concordance rate was 56% for identical (MZ) twins and only 5% for non-identical (DZ) twins.

Conclusion: Anorexia has a genetic basis.

Evaluation: Identical twins share 100% of their genetic material, so other factors must also be involved in causing anorexia nervosa as the concordance

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