Side ASide B
Less than 85% below normal body weight
Failure to lose weight leads to anxiety
DNA inherited from biological parents
Affects approximately 0.5-1% of population
Holland et al (1984)
55% MZ twins concordance rate much higher than DZ twins 7%
Concordance rate not 100% - external factors
Neurotransmitter serotonin may be linked to AN
Linked to depression and OCD
Kaye et al (2001)
PET scans of brain show fewer serotonin receptors in brains of people with AN
Serotonin levels cause or effect?
Low level of receptors could be long term complication of...
Adapt to flee famine hypothesis
Anorexia behaviour adaptive 2 million years ago
AN = restless...
No direct evidence
Refusal of food = death
One person with anorexia may be beneficial for everyone...
Biological Explanations of Anorexia Nervosa
Issues and Debates
Psychology as a science - unfalsifiable
Reductionist - Simplify complex human behaviour