Psychology – Biological Explanation of Eating Disorders.
Psychology Essay The biological approach suggests that AN is due a physical cause, suggesting it could be due to something within the body or brain; such as hypothalamus dysfunction or an imbalance of neurotransmitters. The hypothalamus dysfunction theory would suggest that animals have a “set weight” which is correct for their body, if this weight should increase or decrease then the body should make adjustments to regulate food intake to their “set weight”.
The hypothalamus is thought to have quite a lot of control over our eating behaviour, the lateral hypothalamus (LH) is considered to be the feeding switch that makes an individual begin to feed whereas the ventromedial hypothalamus (VMH) is the satiety switch that makes an individual stop feeding. Garfinkel and Gardner (1982) suggested that a disturbed hypothalamus may be the cause of AN, they proposed that any disturbance could lead to either the LH or VMH to be constantly activated.
In order to explain AN it is most likely that when the LH is damaged and that the individual never receives a signal (feeling hungry) to begin feeding, if the VMH were damaged then the individual would receive a constant signal to eat so they would never stop feeding. This supports the idea that AN might have a biological explanation, specifically brain dysfunction.
Anand and Brobeck conducted an experiment involving the rats, they found that if the LH was damaged it could lead to aphagia (this is a failure to eat when hungry), this provides support for the idea that damage to the hypothalamus can lead to reduced eating which is support for the biological approach of AN. However, there are some concerns with this as the test was conducted with the use of animals so it’s hard to generalise the findings to humans.
This is because humans and animals are biologically different so it’s hard to know if humans would respond in the same way if their LH was damaged. Additional research has shown us that when the VMH in rats is stimulated that it stops feeding, which again supports the suggestion that possible over activation of the VMH could result in reduced feeding. This research would also support the biological explanation of AN as if an individual has damage to their hypothalamus then it could result in reduced feeding which would then result in dramatic weight loss, as seen in sufferers of AN.
However, this theory is reductionist as it suggests that the only explanation of AN is a biological reason, and it ignores other factors; like things such as stress or sexual abuse which can both lead to AN. Another biological explanation of AN would be that there is an imbalance of serotonin, which is usually associated with depression and anxiety; as disturbed levels of serotonin have been found in AN sufferers.
It is also likely that eating disorders arise due to high levels of anxiety which is linked with high levels of serotonin in the body. Bailer et al (1970) compared serotonin activity in recovering anorexia suffers and healthy controls. They found significantly higher activity in the women that were recovering from anorexia, the highest levels found in those women with the highest anxiety levels. This also provides support for AN having a biological cause, in this case an imbalance of neurotransmitters.
However, it’s difficult to establish cause and effect in Bailer’s research, this is because the women studied were already recovering from an eating disorder and so it’s impossible to know whether the imbalance of serotonin was the cause of the women’s AN or whether the AN causes an imbalance of serotonin, so it’s hard to know whether or not there is a biological cause of AN with these findings. In addition to this the research is also gender biased, in this case it’s alpha biased as only women were used in this study but it’s generalising the study to men as well. Bailer’s research also raises the debate of determinism vs. ree will. The biological approach is deterministic so if an individual has an imbalance of serotonin they will then develop an eating disorder, however this is ignoring our free will as an individual that exercises regularly will over their eating; this is noted in individuals who suffer from anxiety but don’t develop AN. Finally there is the evolutionary approach which suggests that all our behaviours are adaptive, which means that the reason we do certain things is to help us survive in a certain way; according to this theory AN is a behaviour which helps them survive.
The evolutionary approach focuses on our ancestors, when weight loss and eating disorders weren’t a consideration and any weight loss would be a lack of food rather than a desire for “thinness”. Usually when an individual begins to love weight physiological mechanisms activate in order to conserve energy and increase desires for food, however it would not have been adaptive for our ancestors to feel hunger as there may not have been much food available to them, so instead it would be adaptive to “switch off” the desire so that they could then find food; in order to help our survival.
Therefore many characteristics of AN can be considered adaptive to enable our ancestors to move to areas where there was more food rather than being preoccupied by looking for food in their current location. However, this theory doesn’t explain the differences of AN between genders, as girls are more affected by AN than boys; so if the behaviour was adapted then both men and women would be equally effected by this as both genders would have had to search for more food in other areas.
An alternative approach to explaining how AN would come from the behaviour approach, which suggests AN is the result of learning rather than a biological explanation. This approach suggests that individuals suffer from AN because of reinforcement, so they have witnessed slim people (who become their role models) being rewarded for their behaviour so they imitate their behaviour in expectation of the same reward.