Anorexia Nervosa Overview (Edexcel A-Level Psychology): Revision Notes
Anorexia Nervosa Overview
Definition
Anorexia nervosa is an eating disorder marked by persistently low body weight in affected individuals.
Diagnostic criteria
Three criteria must be met for a diagnosis of anorexia nervosa:
Understanding the Three Diagnostic Criteria
All three of the following criteria must be present for a diagnosis of anorexia nervosa to be made. Meeting only one or two criteria is insufficient for diagnosis.
Criterion A: Restriction of energy intake
- Results in body weight falling considerably below expectations based on the person's age and height
- Adults with a BMI of or less meet this criterion (a BMI of or below indicates particularly low body weight)
- Standards differ for children and adolescents
Criterion B: Intense fear of weight gain
- Persistent fear of gaining weight or becoming fat
- Behaviour that prevents weight gain despite already low body weight
- Examples include excessive exercise to avoid weight gain
Criterion C: Distorted body image
- Body weight is greatly overestimated and the person cannot recognise the seriousness of their low weight
- Body weight may dominate self-evaluations, leading to poor self-image
- Self-worth becomes overly focused on body weight
Features of anorexia nervosa
Subtypes
The ICD-10-CM defines two subtypes:
Restricting type: Individuals lose weight or prevent weight gain through dieting, excessive exercise or fasting over the past three months.
Binge-eating/purging type: Individuals engage in recurrent episodes of binge-eating combined with purging behaviours such as self-induced vomiting, laxative misuse, diuretic use or enemas over the past three months.
The distinction between these subtypes is important because they may respond differently to treatment approaches and may have different underlying psychological mechanisms driving the disorder.
Demographics and onset
Anorexia nervosa typically develops during adolescence or early adulthood. Onset before puberty or after age 40 is uncommon. Females are diagnosed with anorexia far more frequently than males, with estimates suggesting a ratio of approximately 10:1 female to male. The disorder often begins alongside a major life stressor such as starting university or leaving home.
Timing and Triggers
The onset of anorexia often coincides with major life transitions when individuals face increased stress and changes in their social environment. These transitions can act as triggers for those who may already be vulnerable to developing the disorder.
Physical complications
Although not diagnostic criteria, physical complications frequently accompany anorexia. Amenorrhoea (absence of menstruation) can occur in females due to low body weight. Additional medical problems may arise from malnutrition, including vital sign abnormalities.
Physical Health Consequences
While physical complications like amenorrhoea are not required for diagnosis, they are serious indicators of the severity of the disorder. The absence of menstruation signals that the body is under significant physiological stress due to malnutrition.
Cultural variation
Diagnoses appear more common in high-income countries that are highly industrialised, such as the USA, Europe, Australia, New Zealand and Japan.
Biological explanation: genetics
Research evidence
Recent research indicates that genetics may contribute to the development of anorexia nervosa. Grice et al. (2002) conducted one of the first studies demonstrating a genetic link. The research followed 192 families where one member had received a diagnosis of anorexia nervosa and at least one other member had been diagnosed with anorexia nervosa, bulimia nervosa or another eating disorder. Initial findings showed no clear genetic evidence for developing anorexia until researchers focused on a subgroup of 37 families where at least two relatives had been diagnosed with the restricting type of anorexia. Within this sample, strong evidence emerged for a susceptibility gene or genes on chromosome 1, as similar markers appeared in the affected pairs and groups within each family.
Research published in 2013 by Scott-Van Zeeland et al. identified a more specific genetic link. When comparing 152 different genes in a sample of women with anorexia nervosa against a control group without the disorder, notable differences emerged in and around the EPHX2 (Epoxide Hydrolase 2) gene. This gene is associated with production of an enzyme (Epoxide Hydrolase 2) that metabolises cholesterol. The disorder may therefore be caused, at least partially, by disruption in how the body processes cholesterol, which could affect both mood and eating behaviour.
The Cholesterol Connection
Supporting evidence comes from observations that patients with anorexia often have higher cholesterol levels than expected given their severe malnourishment. In some cases, similar to depression, weight loss can actually increase cholesterol levels (cited in a press release from The Scripps Research Institute, 2013).
Further research by Boraska et al. (2014) found variants in multiple different gene markers in a very large sample of participants with anorexia nervosa from countries around the world. However, none of these findings proved individually notable in the samples chosen, indicating that additional research is needed to determine whether these markers actually contribute to developing the disorder.
Evaluation
Research in this area remains relatively new, and anorexia itself is a disorder about which little is truly understood regarding its origins. Although some evidence supports a genetic explanation, research is still emerging and the extent to which genes can explain the cause of the disorder remains unclear.
Nature vs. Nurture Debate
Many researchers believe that, as with many psychological disorders, multiple factors may work together to cause the condition. Having certain gene markers may increase a person's risk of developing the illness, but other societal or cultural factors may then trigger the onset.
Evidence shows that people with relatives who have eating disorders, such as anorexia nervosa and bulimia nervosa, face an increased risk of eating disorders and other psychiatric disorders such as major depressive disorder and obsessive-compulsive disorder (Lilenfeld et al., 1998). This could support a genetic component in the disorder. However, many of these family members will have spent considerable time in the same environment, meaning the influence of external factors on the development of abnormal eating behaviours or associated mood or anxiety disorders could equally account for the onset of these symptoms. Perhaps the behaviour patterns are learnt through observation of the diagnosed individual.
Separating the biological explanation as a cause of anorexia nervosa from being a result of the disorder proves very difficult. The evidence can demonstrate a relationship between genes, neurotransmitters and neurodevelopmental factors and the development of anorexia, but the causal factors are difficult to determine as anorexia is such a complex disorder. The biological explanations are also complicated by well-documented evidence that poor diet and malnutrition can cause biological changes in the body, making the direction of effect difficult to determine. Regarding prenatal factors and genes, separating what effects may stem from maternal health and diet in a woman with anorexia on her developing foetus from the genetic factors she may pass to her unborn child presents difficulty. This means determining whether the fact the disorder runs in families results from genetics or prenatal factors remains challenging.
Biological explanation: neurotransmitters
Research evidence
Research evidence from Bailer et al. (2005) found that patients who had recovered from a diagnosis of the binge/purge form of anorexia showed increased levels of serotonin in the brain. This was strongly related to measures of anxiety in the women, demonstrating that both increased serotonin and anxiety symptoms persist even a year following recovery. A suggestion has emerged that the serotonin rise may increase levels of anxiety, and this increased anxiety may trigger the binge/purge behaviour of anorexia.
Research has also associated increased activity in dopamine receptors in patients recovering from anorexia nervosa. Kaye et al. (2005) documented increased dopamine receptor activity in areas of the basal ganglia, an area of the brain known to be associated with learning from experience. Overactivity in this area is thought to potentially interfere with patients' ability to seek or respond to pleasurable activities such as eating. It may also interrupt the ability for patients to react to the negative feedback associated with their health such as the image of their emaciated body or symptoms associated with malnutrition.
Dopamine and Pleasure Response
Kaye later (2011) reported that in women with anorexia nervosa, increased levels of dopamine activity increased anxiety, whereas in 'normal' controls the increased dopamine induced feelings of pleasure. This may explain why women with anorexia often experience high levels of anxiety associated with food, something that most people would find pleasurable.
Evaluation
Much of the recent research into neurotransmitter levels is conducted in highly controlled conditions using sophisticated equipment such as brain scans (predominantly PET and fMRI). This means the evidence is highly credible and reliable due to its objective nature. An example of a control measure taken is that in research by Bailer (2005), patients were studied a year into recovery to ensure that malnutrition was not a confounding variable and poor nutrition has been associated with changes in serotonin activity.
Cause or Consequence?
A major criticism of research in this area is that the altered levels of neurotransmitters could easily be a result of poor nutrition rather than a cause. For example, research by Haleem (2012) suggested that serotonin production was associated with a restrictive diet. Tryptophan, an amino acid that is a precursor to serotonin, is only available through diet, so a restricted diet will reduce levels of tryptophan and consequently is likely to reduce levels of serotonin found in the brain. When stored levels of serotonin are reduced, the brain may compensate with up-regulation, which consequently increases the levels of activity. This therefore suggests that the high level of serotonin activity is actually the result and not the cause of anorexia.
Another problem is that drugs used to treat other disorders associated with high levels of serotonin and dopamine, such as SSRIs and neuroleptics, are found to be much less effective in treating anorexia nervosa. This suggests that the cause of the illness is unlikely to be purely related to neurotransmitter levels.
Non-biological explanation: sociocultural theory
Cultural ideals and body image
Anorexia nervosa has long been considered more likely to occur in social and cultural groups that place considerable emphasis on the ideal that 'slim is beautiful'. Research has found that anorexia is more likely to occur in dance or modelling students compared to other female university students, as these groups value the slim body image as part of their image as 'dancers' and 'models' because it is seen as more normal for their body size to be smaller than other groups (Garner and Garfinkel, 1980).
Working in occupations where strong emphasis is placed on body weight increases the risk of developing eating disorders such as anorexia, with diagnoses being considerably higher in occupational groups such as professional dancers, models and elite athletes. Research has even highlighted the 'female athlete triad' of anorexia, athletics and amenorrhea to illustrate the association seen between these three features in young women participating in intense levels of physical activity (Rackoff and Honig, 2006).
Changing Beauty Standards Over Time
Schwartz, Thompson and Johnson (1982) conducted a review of Miss America beauty pageant competitors from 1959 to 1978 and found that over that 20-year period the average weight of contestants decreased. However, at the same time in America, the actual average weight of females was slightly increasing. The body size of the women in the pageant became gradually slimmer, while at the same time, the average body size of 'normal' women was increasing. This suggests that the body type being promoted as 'ideal' and 'beautiful' was actually incongruent with reality, which could make women see themselves as unfairly 'fat' compared to these images.
Garner et al. (1980) also found that over a 10-year period from 1970 to 1980 the number of diet articles in women's magazines hugely increased, suggesting a societal preoccupation with the need to lose weight.
Individual differences and cultural effects
The cultural images and influences mentioned above are something everyone is exposed to, but not everyone develops anorexia nervosa. This suggests that other factors must make some people more vulnerable to these images than others. Research has found that personality factors are associated with diagnoses of anorexia. Evidence has shown that patients with anorexia score highly on measures of perfectionism – a trait associated with serious concern over making mistakes. A person with this trait may be more likely to be influenced by these images and ideals and then develop anorexia.
Anorexia was first diagnosed in western cultures, such as the USA and Europe, and was quite rare in eastern cultures. However, its diagnosis has increased worldwide since the mid-1970s, which coincides with the increased reach of western values into eastern cultures through the media (Iancu et al., 1994). This suggests that cultural values may have notable impact on the development of eating disorders, such as anorexia nervosa, as a method of trying to achieve this 'ideal' body type of slimness.
Cultural Context Matters
Evidence from Hoek et al. (2005) on the island of Curaçao, where it is seen as culturally acceptable to be overweight, found that the overall incidence of anorexia is much lower. In fact, no cases were reported at the time in the majority black population, but the incidence rates in the minority group of white/mixed race population were comparable with that of the United States. This suggests that the influence of cultural ideals is strong, as even when immersed in a culture where a larger size is seen as acceptable, the cultural norm of a smaller body size may still have an effect on the individual's mental health.
Case Study: Cultural Influence on Curaçao
A case study reported by Willemsen and Hoek (2006) considered the case of a black Antillean woman from Curaçao in the Caribbean where previous findings suggested anorexia did not occur. The culture in Curaçao values a larger body size and, while living there, the woman put on weight to become more attractive to gain a partner.
When the relationship started to encounter problems, she lost weight in an attempt to become less attractive. When she emigrated to the Netherlands, the woman continued to lose weight to 'fit in' with the cultural ideals of the slimmer body type and then developed anorexia nervosa.
This case provides support for the influence that cultural ideals can have on body image and the development of eating disorders, demonstrating how changing cultural contexts can affect eating behaviour.
Social learning theory
Social learning theory suggests that we learn through the observation of those we consider to be role models and then imitate the behaviours they show when we find ourselves in a position where we can. Models and other famous figures may be seen as role models to young men and women, and therefore the image they display through the media could easily influence others. The concept of vicarious reinforcement is also important here, as the positive responses given to these famous figures for their looks can teach young people that these body images are something to aspire to.
Cognitive factors
Patients with anorexia tend to demonstrate cognitive distortions in how they view themselves and their body size, which are thought to impact on their body image. Evidence has found that patients with eating disorders in general tend to overestimate their own body size in relation to other people, and often aspire to a body weight that is lower than normal weight control participants (McKenzie et al. 1993).
The 'Size 0' Controversy
The issue of 'size 0' models (referring to the US size 0, which is equivalent to a UK size 4) has been a concern for many eating disorder campaigners, as they argue that the image portrayed that 'fashion is for slim people' and 'people are usually this size' alters girls' own body image because they compare themselves to this ideal. When the average UK female is a size 14-16, there is plenty of room for a negative comparison to be drawn. When considering that 'plus-size models' start from a size 12, the modelling industry certainly seems to offer an altered view of the reality of female body size and, for a vulnerable person, this could be a contributory factor to developing an eating disorder.
Evaluation
Although there is compelling evidence for the effect of cultural ideals on body image, and that this can possibly lead to the development of eating disorders, many people are not influenced by these ideals to the extent of developing the disorder. This suggests that sociocultural factors may simply be one of a number of risk factors that combine to cause anorexia rather than an explanation in itself.
For example, sociocultural factors may only influence the body image of certain people who already have a predisposition to develop the disorder, such as those with biological factors. Other evidence supporting the sociocultural explanation for anorexia comes from the fact that diagnoses of anorexia have increased hugely since the 1950s, which marked the beginning of the change towards slimmer models and the preoccupation with body image and dieting in the media. In recent years, more males have been diagnosed with anorexia, which coincides with changes in men's magazines to include more diet, fitness and body image articles. Both of these factors suggest there is a relationship between changes in cultural views and increased diagnoses of anorexia.
Multifactorial Nature of Anorexia
Despite all of the compelling evidence to suggest that sociocultural factors influence the development of anorexia, the illness is still quite rare in society, and as these images are something everyone is exposed to, we must assume that other factors also combine with sociocultural factors to cause anorexia. Cognitive and personality factors may be a risk factor that, when combined with media images and cultural ideals, increase the likelihood that an individual will become anorexic.
Key Points to Remember:
-
Anorexia nervosa is diagnosed based on three criteria: restriction of energy intake leading to low body weight, intense fear of weight gain, and distorted body image.
-
Genetic factors may play a role, with research identifying potential susceptibility genes (such as the EPHX2 gene on chromosome 1), though it remains unclear to what extent genes explain the cause.
-
Neurotransmitter imbalances in serotonin and dopamine have been found in patients with anorexia, though it's difficult to determine whether these are causes or consequences of malnutrition.
-
Sociocultural factors, including cultural emphasis on slim body ideals and media representations, appear to influence the development of anorexia, particularly in industrialised western societies.
-
Anorexia likely results from a combination of multiple factors (biological, cognitive, sociocultural) rather than a single cause, with certain personality traits like perfectionism increasing vulnerability.