Eating Behaviour . Anorexia Nervosa Unit PSYA3. AQA A Specification. Where we are now. What we have covered. Biological explanations Genetic basis? Serotonin Dopamine Lateral hypothalamus Neurodevelopmental factors Evolutionary explanations Reproductive success hypothesis
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Where we are now
What we have covered
Twin studies (Holland et al, 1984)Looked at the concordance of AN between: -
If the underlying cause of AN is genetic, then there should be a higher concordance in MZ twins than in DZ twins (due to genes).
Twin studies (Holland et al, 1984)Reductionist – only takes one factor (genes) into account.
The concordance rate for MZ twins was well below 100%.
For example, MZ twins may be treated more similarly than DZ twins as they look more alike and therefore they may display similar behaviours (environmental explanation).
Could be that genetics provide a predisposition to AN but other factors also contribute and trigger the onset of AN.Evaluation
Selective serotonin re-uptake inhibitors (SSRIs – drugs), which alter the levels of serotonin in the brain, are ineffective when used with AN patients.
However, Kaye et al(2001) found that SSRIs were effective in preventing relapse and maintaining remission in recovering AN patients.
+ Research has found that adolescents with AN had higher levels of homovanillic acid (a waste product of dopamine) than a control group. Improvement in weight levels was associated with normalisation of homovanillic levels. This supports… and suggests…
- Difficult to establish cause and effect.
- Is this increase in dopamine activity a cause of AN OR is it a result of AN?Evaluation of dopamine and AN
Which part of the hypothalamus is linked to hunger?
If this area is damaged, what happens?
Loss of appetite, no feelings of hunger.
How can we relate this to AN?
If the LH is damaged in AN patients this could partially explain why they starve themselves as they do not experience feelings of hunger.
However, it is much more likely that the development of AN is due to many factors, not just damage to the LH which results in undereating. For example…Brain areas
Complete the gap fill exercise on neurodevelopment explanations of AN.
You have 10 minutes.Independent task
Biological explanations of AN offer the promise of a range of treatment possibilities including: -
If we could use an individual’s genetic profile to indicate the level of risk of AN, we could develop a specifically tailored intervention programme for those susceptible to developing AN.
+ Dealing with dysfunctional biology which is treatable using drugs.Treatment implications (IDA)
E.g. In the USA, treatment for AN is restricted under many insurance plans as it is not considered to be ‘biologically-based.’
This research (serotonin/dopamine/lateral hypothalamus) creates a case for insurance companies to consider AN in the same way as other psychiatric conditions (e.g. schizophrenia) that are considered to be biologically based.Real-world application
Now, write your own!!!IDA