Characteristics and prevalence of anorexia nervosa

Anorexia nervosa is an eating disorder characterised by severe restrictions on food intake, leading to substantial weight loss and potential health risks. It was first identified in 1868 by William Gull and affects individuals from diverse backgrounds, though it is most prevalent among teenage girls.

The Diagnostic and Statistical Manual of Mental Disorders (DSM) outlines three main features

• Restriction of energy intake - Individuals consistently eat fewer calories than needed to maintain a healthy weight, resulting in body weight that is significantly below normal levels.
• Intense fear of gaining weight - Even when underweight, people engage in behaviours such as strict dieting or excessive physical activity to prevent any weight increase.
• Body-image distortion - This involves perceiving oneself as overweight despite being thin, evaluating self-worth primarily based on body weight, and failing to acknowledge the health dangers of low body weight.

Statistics on occurrence and demographics

• Anorexia nervosa ranks among the most common eating disorders in the UK, affecting about 1 in 250 females and 1 in 2000 males.
• It typically develops between the ages of 16 and 17.
• The disorder involves a sharp decrease in food consumption, which causes notable weight loss.

Biological explanations including genetic and neural factors

Biological approaches to anorexia nervosa focus on genetic inheritance and brain-related mechanisms as potential causes. These explanations suggest that physical factors in the body and brain contribute to the development of the disorder.

Genetic influences supported by twin studies

Research indicates a hereditary component to anorexia nervosa.

Holland et al. (1988) study on concordance rates

• Method - Examined 45 pairs of twins where at least one twin had been diagnosed with anorexia nervosa, comparing identical (monozygotic, MZ) twins, who share 100% of their genes, with non-identical (dizygotic, DZ) twins, who share about 50%.
• Results - Concordance rates were 56% for MZ twins compared to 5% for DZ twins, meaning both twins were more likely to have the disorder if they were genetically identical.
• Conclusions - The higher rate in MZ twins supports a genetic basis for anorexia nervosa, though the lack of 100% concordance implies environmental or other factors also play a role.

Neural mechanisms involving the hypothalamus

Damage or dysfunction in specific brain areas may contribute to eating behaviours associated with anorexia nervosa:

• Role of the lateral hypothalamus - This brain region regulates hunger; damage here can lead to reduced eating.
• Evidence from lesion studies - Experiments on animals show that lesions in the lateral hypothalamus cause aphagia, a condition where the animal stops eating entirely.
• Findings in humans - Studies reveal decreased blood flow to the hypothalamus in individuals with anorexia nervosa.
• Causal uncertainty - It remains unclear whether these neural changes cause the disorder or result from prolonged starvation.

Involvement of neurotransmitters like serotonin

Chemical imbalances in the brain may also be linked to anorexia nervosa:

• Individuals with the disorder often have elevated serotonin levels, which are associated with increased anxiety.
• Starvation might temporarily alleviate this anxiety, making restrictive eating feel rewarding.
• The exact causal link is uncertain, as high serotonin could be either a cause or a consequence of the disorder.

Family systems theory as a psychological explanation

Family systems theory views anorexia nervosa as arising from dysfunctional family dynamics that hinder healthy emotional development. This approach, proposed by Minuchin et al. (1978), suggests that family interactions maintain the disorder.

Key features of dysfunctional families

According to the theory, families of those with anorexia nervosa often exhibit specific patterns:

• Enmeshment - Overly close emotional bonds where boundaries between family members' roles are blurred.
• Overprotectiveness - Excessive safeguarding that prevents children from developing independence.
• Rigidity - Inflexible family rules and demands for loyalty, making change difficult.
• These families may seem harmonious on the surface but struggle to resolve conflicts effectively.

Kramer (1983) study on family dysfunction

• Method - Compared family dynamics in individuals with eating disorders to those in control groups without such disorders.
• Results - Found higher levels of dysfunction, such as poor communication and conflict resolution, in families of eating disorder patients.
• Conclusions - Supports the idea that family environment contributes to the development of anorexia nervosa.

Limitations of family systems theory

• Potential for blame - The theory may unfairly attribute the disorder to family behaviour, increasing guilt among relatives.
• Risk of harm from interventions - Attempting to alter family dynamics could distress the patient further if not handled carefully.
• Lack of universality - It fails to explain cases where anorexia nervosa develops in adulthood or after individuals have left the family home.

Social learning theory and media influences

Social learning theory explains anorexia nervosa as a behaviour learned through observing and imitating others, reinforced by social rewards. This perspective highlights how environmental factors, particularly cultural ideals, shape eating habits.

Mechanisms of social learning in anorexia nervosa

• Behaviours are acquired by observing and copying role models, with reinforcement encouraging repetition.
• In Western societies, media promotes slimness as an ideal of beauty and success.
• Individuals imitate admired figures, such as celebrities, who are praised for their thin appearance (vicarious reinforcement).
• Direct reinforcement occurs when family or peers compliment weight loss, encouraging further restriction.
• Over time, this pattern can escalate into full anorexia nervosa.

Keel and Klump (2003) review of media influence

• Method - Analysed global studies on the prevalence of anorexia nervosa and its relation to media exposure.
• Results - The disorder appears worldwide, but rates are higher in societies with greater Westernisation.
• Conclusions - Western media contributes to increased prevalence, though other factors must also be involved since not everyone exposed develops the disorder.

Cognitive theory and overall evaluation of explanations

Cognitive theory attributes anorexia nervosa to faulty thinking patterns about body image and self-worth. Evaluations of all explanations highlight their strengths and weaknesses, emphasising the likely multifactorial nature of the disorder.

Key elements of cognitive theory

• Individuals hold distorted perceptions, such as seeing themselves as fat when underweight.
• Self-worth is overly tied to appearance and control over eating.
• Irrational beliefs about food, dieting, and body shape drive restrictive behaviours.

Gardner and Moncrieff (1988) study on distorted perceptions

• Method - Compared how individuals with anorexia nervosa and a control group perceived images of themselves.
• Results - Those with anorexia were more prone to viewing even undistorted self-images as distorted.
• Conclusions - Supports the role of cognitive biases in maintaining body-image issues.

Strengths of biological explanations

• Practical applications - Understanding neurotransmitter imbalances allows for targeted drug treatments to manage symptoms.
• Reduction of stigma - Framing anorexia as a physical condition helps shift blame away from the individual.

Limitations of biological explanations

• Reductionist approach - Focuses narrowly on biology, overlooking social and psychological influences.
• Inconclusive genetic evidence - While multiple genes are linked, their precise role remains unclear, with mixed study results.

Broader evaluation across theories

• Psychological explanations like family systems and social learning account for environmental triggers but may oversimplify by ignoring biology.
• Cognitive theory addresses thought processes but lacks emphasis on origins of distortions.
• Overall, anorexia nervosa likely results from an interaction of biological vulnerabilities, family dynamics, cultural pressures, and cognitive biases.