- Suggests neural mechanisms and evolutionary factors can contribute towards the development of the condition.
- Research has found that neurotransmitters serotonin and dopamine have an influence over anorexia nervosa (AN). Disturbances in levels of the neurotransmitter, serotonin, appear to be a characteristic of individuals with eating disorders.
- Bailer et al found the highest levels of serotonin activity in women who showed the most anxiety which in turn can trigger AN.
- This is due to the person being more anxious about their weight appearance and so to stop their anxious thoughts start dieting.
- Furthermore dopamine has been associated with AN, as increased dopamine activity in the basal ganglia appears to alter the way people interpret reward.
- Individuals with AN find it difficult to associate good feelings with the things that most people find pleasurable, such as eating.
- Therefore if a person has increased dopamine activity they may not find eating food pleasurable which may then result in them avoiding/ignoring food and this can develop into AN.
+ Supporting evidence for the role of neurotransmitters - Bailer et al found high levels of serotonin in AN patients with binge/purge tendencies when compared to healthy control patients. There were also higher levels of serotonin in those who displayed anxiety. We can therefore draw the conclusion that persistent disruption of serotonin levels could be the cause for increased anxiety which in turn triggers AN.
+ This supports the biological explanation for anorexia because it demonstrates the influence that neurotransmitters such as serotonin can have on AN.
+ In addition to this Kay et al conducted PET scans on 10 patients recovering from AN and 12 healthy people found increased levels of dopamine in the basal ganglia in the AN sample.
+ Therefore it can be assumed that an increased level of dopamine is associated with the presence of AN. Overall, the level of supporting evidence for the role of neurotransmitters suggests that the biological explanation is valid and therefore we can postulate that biological factors are one of the main causes of the development of AN.
- However there are methodological flaws with the supporting studies therefore weakening the explanation of neurotransmitters causing AN. Due to the fact that samples in the above research contained a small number of participants, from Westernised cultures, which were all female, the results are ethnocentrically and gender bias therefore reducing population validity and thus generalizability.
- The results are bias towards the female gender and because of this it would be inaccurate to conclude that the same results would be seen in males if they experienced changes in serotonin and dopamine levels.
- Because the evidence in support of this biological explanation have methodological issues in turn weakens the validity of the whole biological explanation due to the fact that we cannot be sure this effect will also be seen by all people experiencing disturbances in their levels of neurotransmitters. Therefore more research needs to be conducted into this area using a wider range of participants so that conclusions can be drawn that apply to a wider range of people.
- A second biological explanation of AN is the evolutionary explanation. The reproduction suppression hypothesis by Surbey suggests that adolescent girls desire to control their weight represents an evolutionary adaption in which ancestral girls delayed the onset of sexual maturation in response to cues about the probability of poor reproductive success.
- The ability to delay reproduction is adaptive because it enables a female to avoid giving birth at a time when conditions are not conductive to her offspring.
- Observations have been made that show when females, from a variety of species, are subjected to stress or are in poor physical condition, puberty is delayed or reproduction is suppressed. Therefore in modern time if a girl feels she cannot cope with becoming an adult or is put under stress, AN may develop as an emergency coping mechanism to deal with these feelings.
- Since amenorrhoea is a typical characteristic of AN, this means that reproduction is effectively suspended in anorexia females.
- However, there are problems with this evolutionary explanation due to it being based on the evolutionary approach, which in itself has issues, such as being speculative. This means that the explanation does not have a factual basis and is highly subjective so it is difficult to prove that the explanation is true.
- With anorexia we can never exclude factors like social and cognitive influences and therefore the 'reproduction suppression hypothesis' can never be tested scientifically, so a cause and effect relationship between reproduction suppression hypothesis and AN can never be established.
- This weakens the specific evolutionary explanation to AN as it suggests that there may be other factors involved in explaining why people develop the condition of AN other than the reproduction suppression hypothesis.
- The biological explanations of AN sit on the reductionist side of the reductionism-holism debate. This is because only biological explanations are considered and no thought is given to other factors such as psychological or cognitive factors. This means that only one side of the argument is considered which then leads to only half a cure being found.
- Being reductionist means we cannot establish a paradigm when considering reasons for AN as other approaches have been excluded.
- However being reductionist can also have its strengths as it allows us to analyse the biological explanations for AN in greater depth and get a full valid understanding of that one factor alone.
- Overall a holistic approach would be more appropriate as it would consider how differing factors interact together to cause the condition of AN. This would then result in more effective and appropriate conditions being established for those with the condition and thus improve their chances of making a full recovery.