Bio Expla of AN

• What does the genetic explanation describe anorexia to be

  The genetic explanation describes anorexia to be an inheritable disorder which is passed through generations through DNA
• Twin studies in relation to AN - who, findings, conclusion

  Twin studies are used to investigate the role of genes in AN. Holland et al looked at 45 pairs of twins who had AN and found a CR of 56% for MZ twins and 5% for DZ twins. Because of the significantly higher CR in MZ twins compared to DZ twins regarding AN, we can conclude that AN is heavily genetically based
• Candidate gene in relation to AN - who, findings, conclusion

  Scott-Van Zeeland identified the main candidate gene for AN. He identified that several variants of the EPHX2 gene have an association with AN. Since the gene is involved in cholesterol function, it explains why anorexics have an abnormal level of cholesterol
• Dopamine - AN - who + findings

  Kaye et al found that overactivity in dopamine receptors in the basal ganglia where dopamine is responsible for the interpretation of harm and pleasure
• Dopamine - AN - abnormal dopamine activity - where, what, explains

  Abnormal dopamine activity in the basal ganglia alters the way we interpret rewards. This explains why people with AN find it difficult to feel pleasure from food. This contributes to their avoidance of meals
• Serotonin - AN - who, findings

  Bailer and Kaye found that individuals with AN report high levels of anxiety prior to developing the disorder and believed it was linked with high levels of serotonin
• Serotonin - What leads to anxiety in anorexics and how do they decrease it - steps

  • High levels of serotonin leads to anxiety in anorexics,
  • If they disrupt serotonin synthesis, they're granted temporary relief from anxiety
  • Serotonin synthesis requires adequate levels of tryptophan which is an AA
  • When ANs skip meals, they lack nutrients to create tryptophan and thus, serotonin.
  • Lack of serotonin decreases anxiety
• Serotonin -what does skipping meals act as

  Skipping meals acts as a way to regulate overactivity of serotonin and improve mood
• Serotonin - Kaye et al findings + what do they suggest

  • Kaye et al found that reduced tryptophan was linked to reduced anxiety in people with AN
  • Suggests that self starvation and eventually AN is caused by the desire to re-balance serotonin activity in order to avoid anxiety
• Eval points for the genetic explanation

  • Reductionist
  • W - relies on twin studies which have a methodological flaw
• W - genetic explanation is that it's reductionist. Oversimplifies complex behaviour of AN down to just genes. Ignores other factors that can contribute to the development of AN such as observation, imitation and vicarious reinforcement. Vaughn + Fouts - longitudinal study - found adolescent girls whose AN symptom severity increased over a 16 month period also reported significantly greater fashion magazine reading over the same period. W bc ...
• (W - genetic explanation - reductionist)... W bc it shows that you can in fact develop AN through SLT concepts like vicarious reinforcement e.g. girls may see the models in magazines get praise and thus engage in anorexic tendencies in an attempt to imitate the models. Genetic explanation decreases validity
• W - genetic explanation - relies on twin studies which have a methodological flaw. Twin studies assume the higher CR for in MZ twins (100%) compared to DZ twins (50%) is bc they share more genes. Overlooks the possibility that the real reason behind higher CR is bc MZ twins are treated the same due to looking the same. The studies make the "equal environments assumption" where they assume that the environment that MZ and DZ twins share are equal in influence, when in reality, the environment that MZ twins have influenced them greatly. V of twin studies is Q - genetic explanation decreases in V
• S - neural explanation - research support for role of dopamine. Previous research has found that high levels of dopamine can lead to an increased eye blink rate in ppl. Additionally, Barbato found increased eye blink rate in ppl with AN (with the longer the duration of having AN, the higher the blink rate) compared to control group. S bc this shows that it's plausible that the increase in dopamine may in fact be responsible for anorexic tendencies such as avoidance of food and thus subsequent weight loss. Increases validity
• Eval points for neural explanation of obesity

  • S- Research support for the role of dopamine
  • W - evidence it relies on is correlational
• W - neural explanation - evidence it relies on is correlational. Explanation argues abnormal levels of dopamine cause AN. We don't know if abnormal levels of dopamine cause AN or if abnormal levels of dopamine is a symptom of AN. If former is true = explanation is validated. If latter is true + cause for AN is in another explanation. For example, AN may be caused be cog distortions. This possibility is validated by Fairburn et al. Found CBT-E was effective in treating AN symptoms in 2/3 of Ps thus indicating there's a cog element to AN. Relies on correlational evidence - decrease validity