Anorexia
Description |
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Less than 85% below normal body weight
Failure to lose weight leads to anxiety
Body perception distorted
Dry skin, dehydration, malnutrition, brittle nails, thinning hair, amenorrhea and fine hair growth
90-95% female
90% severe cases start at 13-18 years |
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Genetic
Description |
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DNA inherited from biological parents
Affects approximately 0.5-1% of population
Families with one relative with disorder - 4-5% chance |
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Genetic
Holland et al (1984) |
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55% MZ twins concordance rate much higher than DZ twins 7% |
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Genetic
Evaluation |
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Concordance rate not 100% - external factors |
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Neurological Explanations
Description |
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Neurotransmitter serotonin may be linked to AN
Linked to depression and OCD
Studies suggest serotonin levels low in AN
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Neurological Explanations
Kaye et al (2001) |
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PET scans of brain show fewer serotonin receptors in brains of people with AN |
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Neurological Explanations
Evaluation |
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Serotonin levels cause or effect?
Low level of receptors could be long term complication of AN
People with Anorexia do still feel hungry |
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Evolutionary Explanation
Description |
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Adapt to flee famine hypothesis
Anorexia behaviour adaptive 2 million years ago
AN = restless and higher levels of activity
Higher activity levels and denial of hunger help to migrate |
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Evolutionary Explanation
Evaluation |
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No direct evidence
Refusal of food = death
One person with anorexia may be beneficial for everyone else |
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Biological Explanations of Anorexia Nervosa
Issues and Debates |
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Psychology as a science - unfalsifiable
Reductionist - Simplify complex human behaviour
Nature/nurture - Focus on biological causes of behaviour
Gender bias - Most research carried out on females |
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