These fall into two categories – genetic inheritance or an imbalance of neurotransmitters in the brain.
* Science unable to identify genes for specific behaviour such as those associated with eating disorders
* Research is based on trends in families
* American Psychiatric Association reports from statistics that there is increased risk of eating disorders amongst first-degree biological relatives of those diagnosed.
* However relatives usually share the same environment [nature vs. nurture]
* Twin studies provide more reliable evidence. In comparing monozygotic (MZ) twins with dizygotic (DZ) twins, a significantly higher concordance rate was found among MZ twins compared with DZ twins.
* Twin research into anorexia by Holland et al. found a 55% concordance rate for MZ twins compared to only 7% for DZ twins
* Kendler et al. found similar results for bulimia nervosa, with 23% for MZ twins and 8.7% for DZ twins.
* Even though the results from these studies show very high concordance rates, in Holland’s study it still leaves 45% of MZ twins who are discordant.
* Hsu suggested that the genetic element might relate to personality traits which make the person more susceptible to stressful events. Which could manifest in the form of an eating disorder.
* In many cases of anorexia and bulimia, there is family history of mood or personality disorders.
* Wade et al studied both genetic and environmental risk factors in 325 female twins, and found significant environmental influence in shaping women’s attitudes towards weight, shape, eating and food … but little evidence of a genetic component.
* Eating disorders may be associated with a biochemical imbalance. Research of the brain has focused on the region known as the “hypothalamus.”
* Animals have been found to stop eating or even starve themselves to death when this part of the brain is damaged.
* According to Keesey and Corbett, the lateral hypothalamus and the ventromedial hypothalamus work alongside each other to provide a ‘weight thermostat,’ sending messages about being hungry/full up.
* A malfunction in this part of the hypothalamus offers a possible explanation for eating disorders although there is as yet no conclusive evidence
* Amenorrhoea can occur before weight loss, suggesting a primary disorder of low endocrine levels – which is also associated with hypothalamus dysfunction.
* More recent research has focused on certain hormonal chemicals (norepinephrine, dopamine and low levels of serotonin…associated with binge eating)
* Walsh et al. have found that most effective drug treatment for bulimia is serotonin-active antidepressant medication.
* Jimmerson et al. conducted clinical tests comparing serotonin functions in patients with bulimia compared to healthy controls. They found considerable differences and concluded that impaired serotonergic responsiveness may contribute to the abnormal eating patters in people with bulimia.
* The problem with biochemical research is that is difficult to differentiate between the cause and the effect i.e. starvation may eventually cause an imbalance in biochemical functioning.
* Classical Conditioning incorporates the layperson’s view, suggesting that slimming becomes a habit, through stimulus-response mechanisms. They learn to associate being slim with feeling good about themselves
* Operant Conditioning comes into play as admiration from others further reinforces the dieting behaviour. Refusing to eat my also provide an additional reward in gaining attention from parents, and starving oneself can even be rewarding as an effective way of punishment.
* Cross-cultural studies seem to support the behavioural explanation. Anorexia and bulimia are more prevalent in industrialised societies like Europe, USA, Canada, and Australia etc. In these societies there is an abundance of food yet being attractive is associated with being slim
* The American Psychiatric Association states that immigrants from cultures where these disorders are rare have been found to develop anorexia just as quickly once these ideals of attractiveness are assimilated.
* A study by Nasser compared 50 Egyptian women in London universities compared with 60 in Cairo universities. 12% of those in London developed an eating disorder. None of those in Cairo did
* However another study by Mumford et al. of Asian schoolgirls living in Bradford found that concerns about weight and body shape were more associated with their Asian culture than their Western experience.
* There are too few studies in non-industrialised countries so it is quite difficult to compare.
* Other studies, such as that by Pike and Rodin, have identified family pressures on daughters to be thin…particularly from perfectionist mothers.
* That patients have an irrational belief system whereby the person firmly believes they cannot be valued unless they have an ideal physical appearance
* People with eating disorders often have a distorted body image and perceive themselves to be unattractive owing to their being fat.
* However most people who diet because of social pressure don’t’ become anorexic, which is why distorted perceptions may offer a valid explanation
* Bemis-Vitousek and Orimoto found a consistent pattern of distorted thinking among people with anorexia. They also found irrational attitudes about control.
* Fairburn et al. conducted an interview comparing 169 people with eating disorders, 102 people with other psychiatric disorders and 204 healthy controls. Perfectionism and negative self-evaluation were high risk factors found for both anorexia and bulimia.
* It is not clear though, in this explanation, where there irrational beliefs come from in the first place.
* Freud maintained that eating is a substitute for sexual expression and therefore in psychoanalytic terms, anorexia could be viewed as the persons way of repressing sexual impulses.
* Hilde Bruch suggested that anorexia is associated with psychosexual immaturity in a number of ways. One suggestion is that women have fantasies of oral impregnation and confuse fatness with pregnancy. The unconsciously believe that eating will lead to pregnancy and therefore starve themselves.
* Another suggestion is that eating becomes equated with taking on adult sexual role and that women who cannot face this, starve themselves in order either to remain children or to regress to childhood
* Eating disorders have been strongly linked to early traumatic experiences, and psychotherapy studies indicate that a large proportion of patients report early experience of sexual abuse
* McLelland et al. conducted a study in an eating disorder clinic, and reported that 30% of clients had a history of childhood sexual abuse
* However not all people who have experienced childhood sexual abuse develop an eating disorder and not all people with eating disorders report having been sexually abused as children
* Another suggestion is that early traumatic experiences are repressed and then becomes expressed in later life in ways associated with gender socialisation. Females are taught to be self-critical and subservient, and early trauma is turned inwards in the form of self-harm. Men are taught to be dominant and outwardly expressive, so early trauma is more likely to be expressed as hostility towards others
* A study by Carlat et al. concluded that sexual orientation was a major factor I male eating disorders, with over 42% of the group being homosexual/bisexual.
* Eating disorders relate to family relationships, in particular to the adolescents struggle to gain a sense of individual identity.
* In some family relationships, children grow up without a sense of their own identity and consequently with a low self-esteem.
* A daughter may struggle for her identity by refusing to eat the food her mother cooks.
* Anorexia is much more prevalent in middle-class families, and by those whose parents are professionals. This leads to suggestions that family pressure to “succeed” may be too great for some young people and may lead to psychological problems such as depression and anorexia
* A study by Fairburn et al supports the humanistic explanation, because negative self-evaluation was identified as a high-risk factor for bulimia, along with parents who had high expectations for their daughters and yet had low contact with them.
* A longitudinal study on 459 girls diagnosed with bulimia by Joiner et al concluded that the most significant factors sustaining the disorder over the 10yr span were a drive for thinness, maturity fears, perfectionism and interpersonal distrust.
* Minuchin et al suggest that the development of anorexia serves the function of preventing dissension within the family.
* A study by Hill and Franklin found little evidence of mothers influencing their daughters regarding issues of weight and attractiveness. However they did find that there were perceived problems in family functioning
* Family relationships are thought to be a central feature in eating disorders, so much so that family therapy is currently the most significant form of intervention for eating disorders.