Biological Explanations of Anorexia- Neural Factors
- Created by: rhallett
- Created on: 12-12-15 12:51
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- Biological Explanations for Anorexia - Neural Factors
- NTMs
- NTMs are chemicals which enable neurons in the brain to communicate. If NTM systems which regulate food intake are not working properly this will cause abnormalities in eating behaviour.
- Dopamine is an NTM which plays a part in the rewrding feelings people normally get from food and it has been linked to anorexia
- +Kaye used PET scans and found high levels of dopamine activity in the basal ganglia of 10 women who were recovering from anorexia, compared to a control group; might reflect fact that anorexics find dierting and weight loss reinforcing
- Fits in with the finding by Volkow that obese people have a lack of dopamine receptors. Both these findings suggests that high levels of dopamine play a role in anorexia
- +Research found that adolescent girls with anorexia had higher levels of homovanillic acid which is a waste produce of dopamine-also suggesting that high levels of dopamine might play a part in anorexia. Moreover as they gained weight their levels dropped to normal
- -There are problems with these studies; it's possible that these abnormalities are long term effects of anorexia itself, not its cause; may not show anything about the cause of anorexia. Also small samples so may not be valid
- +Kaye used PET scans and found high levels of dopamine activity in the basal ganglia of 10 women who were recovering from anorexia, compared to a control group; might reflect fact that anorexics find dierting and weight loss reinforcing
- Hypothalamus
- Hypothalamus seems to control eating behaviour and it has been suggested that abnormalities in it may cause anorexia
- +Research on rats found that lesions in the lateral hypothalamus produced a lack of appetite and cause the rats to lose weight; similar to anorexia
- -However, research on rats may not apply as they have simpler brains and their eating is less effected by social and cultural factors. Rats don't have all the features of human anorexia; research is also unethical
- +Also evidence linking the hypothalamus to anorexia. Small number of cases of tumours in this area of the brain which have been found to cause reduced appetite and produce anorexic like symptoms. Eg 1972 Lewin reports the case of NZ nurse
- -However, no evidence has been found that damage to the lateral hypothalamus can cause anorexia nervosa in normal humans who don't have tumours
- Birth Complications/ Season of Birth
- +Lindberg has shown that children born prematurely/ had birth complications have a higher risk of developing AN in the future. Could be because birth compliactions may lead to brain damage caused by hypoxia- lack of oxygen
- -However this type of research is hard to draw conclusions from because it doesn't identify a neural abnormality linked to anorexia, though it suggests there might be one
- +Anorexics are more likely to be born in the spring; possibly because their neural development is affected in utero by an infection contracted by their mother. Infections are more common during the winter months which is why people 'in utero' during this period are more likely to be affected.
- -However, this theory is speculative because research has not shown a virus having this effect
- +Lindberg has shown that children born prematurely/ had birth complications have a higher risk of developing AN in the future. Could be because birth compliactions may lead to brain damage caused by hypoxia- lack of oxygen
- NTMs
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