The Hypothalmus & neurotransmitters-Kaplan & Woodside(1987) damaged the hypothalmus of rats who then couldn't stop eating. Seems NE makes you eat (preferably carbs) Serotonin induces feelings of satiation. Carraso(2000) found lowere levels of serotonin in Bulimic patients.
Genes-Kendler(1999) concordance rate of 23% for MZtwins & 9% for DZ. Askevold & Heiberg(1979) 50% concordance rate for MZ same environment. Hollander(1984) 55% MZ & 7% DZ. No evidence for twins reared apart diff. to evaluate.
Evaluation-Rates for MZtwins are always higher-suggesting a genetic link. Studies from rats can't be generalised to humans (the rats weren't vomiting). Concordance rates vary enormously, if it was all genes MZ rates should be 100%. Bulimics secretive so self report not reliable. Reductionist & deterministic. Eating behaviour is also influenced by cognitive, social & cultural factors.
Cognitive & Socio-cultural Explanations
Cognitive-Emphasise that the thought process of a bulimic is often negative, irrational & incorrect. Slade & Brodie(1994) those who suffer from eating disorders are uncertain about size & shape of their body so when have to make a judgement overestimate.More descriptive than explanatory. Diff. to study cause & effect-distorted eating could lead to distorted thinking vice versa. Underemphasise role of biological factors.
Sociocultural-Crisp(1967) eating disorders kind of weight phobia. Hill(1996) if women see slimness as desirable perceive own bodies as larger-start dieting to become slimmer. Hamilton & Waller(1993) when women with eating disorders shown pictures of idealised female bodies over-estimated own body sizes. Fear(1999) sudden increase in eating disorders among teenage girls in Fiji after TV arrived. Lee(1992) eating disorders lower in non western societies. Immigrant pop. develop eating disorders when move to western societies. Why do blind ppl get bulimia? Other studies show just a prevalent but classified in a different way- India seen for religious reasons, Caribbean seen as symptoms of other disorders.