1. Session 9: Etiology of Bulimia Nervosa

2.  Analyse etiologies (in terms of biological, cognitive and sociocultural factors) of Bulimia Nervosa

4. Kendler et al (1991)  Aim: to investigate risk factors and genetic inheritance in bulimia nervosaProcedure:  Sample of 2,163 female twins  One of twins in each pair had developed bulimia  Longitudinal study  Researchers conducted interviews with twins to see if other twin would develop bulimia  Compared to see if concordance rates higher with monozygotic twins (MZ) than dizygotic twins (DZ)

5. Kendler et al (1991 Kendler et al (1991)  Results: concordance rates of bulimia with twins  Results indicate a heritability of 55% but this leaves 45% for other factors MZ TwinsMZ TwinsDZ TwinsDZ Twins23%9%

6. Evaluation Kendler et al (1991)  Study was a natural experiment therefore researchers did not manipulate any extraneous variables and there was no control condition so it is not possible to establish cause and effect relationship  Questionnable whether twins are representative of general population-perhaps some aspect of being a twin puts people more/less at risk of developing a disorder  All women so cannot be generalised to men  Study does not take into account environmental factors. It could be that twins grow up in same environment/are exposed to same environmental risk factors such as a dysfunctional environment  Genetic vulnerability may predispose an individual but other factors may trigger disorder. Very important to study environmental factors too.  Because of highly secretive nature of bulimia, self reporting may not be best method of data collection

7.  Other twin studies also demonstrate higher concordance rate of bulimia in MZ twins than DZ twins, but rates vary from 23%-83%  Strober (2000) found that first degree relatives of women with bulimia are 10 times more likely than average to develop disoder themselves  These differences in findings could be attributed to both the method of data collection and varying definitions of the disorder  Because of highly secretive nature of disorder self report has not always led to reliable data  Its possible that some of these familial links could be due to some shared aspect of environment

8.  Serotonin is a neurotransmitter associated with mood, hunger and sleep  Serotonin appears to play a role in bulimia  Increased serotonin levels stimulate the medial hypothalamus and decrease food intake  Carraso (2000) found lower levels of serotonin in bulimic patients

9.  Smith et al (1990) found that when serotonin levels were reduced in recovered bulimic patients, they engaged in cognitive patterns related to eating disorders, such as feeling fat

11. Body-image distortion hypothesis (Bruch, 1962)  Bruch (1962) claimed many patients with eating disorders suffer from the cognitive delusion that they are overweight.  Research has demonstrated that many ED sufferers overestimate their body size  However, these studies have also shown that degree of distortion varies considerably with contextual factors including the precise nature of instructions given to subject  Nonetheless, it appears that at least some reports given by patients demonstrate that they evaluate their own body size, they are influenced by emotional appraisal rather than their perceptual experience

12. Body-image distortion hypothesis uncertain In a reformulation of body-image distortion hypothesis, Slade and Brodie (1994) suggest that those who suffer from an ED are in fact uncertain about the size and shape of their body, and that when compelled to make a judgment they err on the side of reporting an overestimation of their body size.

13. Body-image distortion hypothesis  There seems to be a gender difference in perception of body image  Provides anecdotal support for B.I.D hypothesis as there are also gender differences in prevalence of bulimia Fallon and Rozin (1985)  Aim: To compare gender differences in body image and desired body shapeProcedure:  475 US undergraduate of both sexes  Showed 9 pictures of different body shapes from very thin to very heavy  Asked participants to indicate: ◦ Body shape most similar to their own ◦ Ideal body shape ◦ Body shape of opposite sex they would be most attracted to

14. Body-image distortion hypothesis Fallon and Rozin (1985) Results:  Women consistently indicated that their current body shape was heavier than the most attractive body shape  Their ideal body shape was much thinner than the one they had chosen for their own body shape  Men chose similar figures for all three body shapes  Researchers concluded that men’s perceptions helped them stay satisfied with body shape whereas women’s perceptions put pressure on them to lose weight.  These sex differences could probably be linked to a higher prevalence of dieting, anorexia and bulimia among US women.

15. Role of Cognitive Disinhibition  In addition to perceptual distortions, Polivy and Herman have looked at the role of cognitive disinhibition  This occurs because of dichotomous thinking- an all or nothing approach to judging oneself  Bulimics follow very strict dieting rules in order to reach the weight that they feel is ideal  When they break their own rules, they tend to binge eat  Thoughts about eating (cognitions) act to release all dietry restrictions (disinhibiton)

16. Role of Cognitive Disinhibition Polivy and Herman (1985)  Asked dieters and non-dieters to take part in a taste test  Before taking part in test, they were given a chocolate milkshake  After drinking milkshake, they were given 3 types of ice cream to sample  Told they could eat as much as they liked

17. Role of Cognitive Disinhibition Polivy and Herman (1985) Results Dieters ate significantly more than non-dieters Study raises interesting questions: if 3/4 women diet at some point in their lives but only 1/33 suffer from bulimia, why do we not see more bulimia?

18. Weight related schemata model  Fairburn (1997) suggested people with eating disorders had distorted weight related schemas and low self-esteem  Distorted beliefs and attitudes towards body shape and weight develop partly because of the high status given to looking thin and attractive  Individuals strive to control body weight to stay thin and they base self worth on being thin i.e. they have a weight related self schema that distorts the way they percieve and interpret their experiences

19. Weight related schemata model  For some people, their concerns and prioritisation of weight control may reflect a wider lack of self-esteem and a vulnerability to cultural messages about body weight  They think they will feel better if they lose weight but this obsession with weight control may lead to depression and intensified feelings of low self esteem because weight control is their main way of maintaining self worth

20.  Cognitive explanations of bulimia that patients suffer from perceptual distortions and maladaptive cognitive patterns are more descriptive than explanatory  It does not explain how these distortions arise in the first place  It is very difficult to establish cause and effect since disordered eating patterns may result in distorted thinking rather than vice versa

22.  Perceptions of the perfect body are influenced by cultural ideals  In the West, images of the ideal body shape for women have changed over the years from an hourglass shape to a slimmer shape.  In the 1950s female sex symbols had much larger bodies compared with those of the present day  Celebrities represent an ideal that people compare themselves to, so they establish standards for how we should look whether they intend to or not

23.  People constantly compare themselves to other people and their self esteem is affected by this  Thanks to the media, we have become accustomed to extremely rigid uniforms of beauty  Television, billboards and magazines expose us to “beautiful people” all the time, making exceptional good looks seem real, normal and attainable

24.  Standards of beauty have in fact become increasingly difficult to attain, particulalry for women.  The current media ideal of thinness for women is achieveable by less that 5% of the female poplulation

25.  Many eating disorders begin when a young women who is not substantially overweight comes to believe that she needs to go on a diet  Aspects of the woman’s personal history, biological make-up and thought processes may contribute to dissatisfaction with body weight, but the desire to be thin is often powerfully influenced by media images and messages

26.  The media both reflects and helps to shape a strong cultural pressure towards thinness  The rise in the incidence of eating disorders which has become evident in recent years throughout Europe, and in the US and Japan is frequently attributed to an increase in cultural emphasis on thinness as an ideal boyd shape

27.  The representation of the ideal female as thin is also apparent in coverage of children’s fashion and in the design of dolls so even very young girls are subjected to distorted models of ideal body shape. Sanders and Bazalgette (1993)  Analysed the body shape of 3 of most popular dolls available for young girls (Barbie, Sindy and Little Mermaid)  Measured height, hips, bust and waist.  Then transformed measurements to apply to a real woman of average height  Relative to real women all dolls had tiny hips and waists and greatly exagerrated leg lengths

28.  Distorted ideas about what is normal and acceptable mean that many women, even children become dissatisfied with their own shape even though it is within the healthy range.  Waddle and Marsland (1990) report that by the age of 12, body shape can be a major criterion in self evaluation and the evaluation of others and that many people have prejudices against overweight people.

29.  Men, too are beginning to come under pressure.  The ideal “worked out” male figure that appears in many commericals produces a strong demand to mirror the ideal  In 1993, a MORI survey of adult males in UK found that:  1/3 of men had been on a diet  2/3 of men believed a change in shape would make them more sexually attractive  It remains to be seen whether the growing emphasis on an ideal male shape will lead to an increase in the number of men who suffer from EDs

30. Levine et al (1990)  Aim: to investigate relationship between sociocultural factors and eating attitudes and behaviours Procedure:  USA, 385 girls aged 10-14 years  Answered questions about eating behaviour, body satisfaction, concern with being thin, parents’ and peers’ attitudes, and magazines with regard to weight management techniques and the importance of being thin

31. Levine et al (1990) Results  Majority of respondents said they received clear messages from fashion magazines, peers and family members that its important to stay thin  Also reported the same sources encouraged dieting or other methods to keep a slender figure  Study found 2 important factors in drive for thinness and disturbed patterns of eating: 1.Reading magazines containing information about ideal body shapes and weight management 2.Weight related teasing or criticism from family

32. Levine et al (1990) Conclusions  The results indicate that body dissatisfaction and weight concerns reflect sociocultural ideals of a female role and raises the possibility that some adolescent girls live in a subculture of intense weight and body image concern that places them at risk for disordered eating behaviour such as bulimia nervosa

33. Jaeger et al (2002) Aim: to conduct a cross cultural investigation of the relationship between body dissatisfaction and the development of bulimia to see if there were cross cultural differences in vulnerability to bulimiaProcedure:  Cross cultural sample of 1751 female medical and nursing students from 12 nations including western and non-western countries  This was a natural experiment as the IV (culture) could not be controlled by experimenter

34. Jaeger et al (2002) Procedure:  Self report method used to obtain data on body disatisfaction, self esteem and dieting behaviour  Participants’ BMI (height and weight) was taken  Participants saw a series of 10 body silhouettes, designed to be as culture neutral as possible in order to measure body dissatisfaction

35. Jaeger et al (2002) Results  Significant differences between cultures were found  Most extreme body dissatisfaction found in Mediterranean countries followed by northern European countries  Countries in process of weternisation showed an intermediate amount of body dissatisfaction  Non-western countries showed lowest levels of dissatisfaction  Body dissatisfaction was found to be most important factor in dieting behaviour in most countries

36. Jaeger et al (2002) Conclusions  The significant differences between cultures support the explanation that bulimia is due to “idealised” body images portrayed in media which encourage disorted views and consequently, body dissatisfaction and dieting.  Western countries are more exposed to these images and show higher body dissatisfaction  Implications are that explanations of disorder must be considered at a macro-level (society) rather than origninating solely within individual (micro-level)

37. Jaeger et al (2002)

38.  Study was a natural experiment and uses culture as a variable but it is impossible to establish cause and effect ere as “culture” is not a controlled variable. Causation cannot be inferred.  Ignores the role of genetic factors in causing bulimia, even though heredity certainly plays a part in development of disorder  It is not easy to separate nature/nuture but it is oversimplified and reductionist to consider only one explanation  Participants were all medical or nursing students. Such reltively well-educaated groups do not form representative samples and it is not at all clear that other groups in each country would have similar levels of disatisfaction

39.  The causes of bulimia appear to be multifaceted  Research suggests that bulimia develops due to a complex interaction from a range of factors including biological, cognitive and sociocultural