Biological Anorexia Flashcards
Possible biological causes include
Genes
Serotonin
Dopamine
Season of birth
Neural mechanisms
Lateral hypothalamus produces feelings of hunger, Ventromedial hypothalamus tells us when we are satiated damaged Ventromedial hypothalamus leads to not being able to stop eating. Damage to lateral hypothalamus could result in aphagia and therefore possibly anorexia
Genes
If anorexia is solely due to genetic causes then twins should have a 100% concordance rate
Study for Genes
Holland found high concordance rate for identical female twins - 56%
Compared to non identical - 7%
- NOT 100%
- does have some genetic component
Criticism for genes
Wade et al studied Australian female twins and found that anorexics also has families which often commented on weight. Suggested a social cause not biological
Serotonin
Increased serotonin in the brain is associated with suppressed appetite, increased anxiety, obsessive behaviour, phobias and vomiting. Starvation lowers tryptophan which is needed to manufacture serotonin. Restricted food intake means that tryptophan drops and so does serotonin, so by starving the anorexic feels better.
Strength for serotonin
Fichter + Pirke starved normals and found these chemicals changed. So supports the idea that high levels of serotonin are linked to anorexia nervosa.
Weakness for serotonin
Most drug therapies which alter levels of serotonin are ineffective for anorexia which shows that there most be other causes of illness
Dopamine
Castro-Fornieles also found that girls with anorexia nervosa had higher levels of dopamine suggesting a correlation between anorexia and increased levels of dopamine.
Neurodevelopment
Research suggests that individuals with anorexia nervosa were more likely to have been born in the sprint.
So there may be a correlation with temperature/infection etc with the second trimester of pregnancy
Support for neurodevelopment
Eagles found that the second trimester of pregnancy is the most important for development and so Spring babies experience this second trimester in the winter when infections are rife
Advantages of biological research
- faulty biology reduces the guilt of parents
Problems with biological anorexia
- small sample sizes
- reductionist as there is no one simple cause
- can’t explain why concordance rates aren’t 100%
- deterministic
Reproductive-suppression hypothesis
Survey proposed that adolescent anorexics can be explained by the notion that if the chance of reproductive success is low and so she controls her body accordingly. Reproductive suppression hypothesis is supported by the observation that menstruation is delayed in anorexic girls.
Weakness of reproductive suppression hypothesis
Evolutionary explanations can’t be proved
Deterministic
Reductionist
