Clever Grades

🎧 Read Aloud

Biological Explanations for Anorexia Nervosa

Anorexia Nervosa: Core Characteristics

What is AN?

Anorexia nervosa (AN) is a serious eating disorder characterised by an intense fear of gaining weight and a distorted body image, leading to severe food restriction and underweight status. Biological explanations focus on genetic predispositions and neural abnormalities that contribute to the disorder’s development and maintenance.

Genetic Explanations: Key Evidence

Research using twin and family studies provides evidence that anorexia nervosa has a heritable component.

1

Twin Studies

Concordance rates for anorexia nervosa are higher in monozygotic (identical) twins compared to dizygotic (fraternal) twins.
2

Family Studies

Relatives of individuals with anorexia nervosa show increased risk of the disorder and related psychopathologies, like anxiety or depression.
3

Candidate Genes

Research has explored genes linked to neurotransmitter systems and appetite regulation.

Heritability: Twin & Environment

✅
The Pros (MZ Twins) Studies suggest heritability estimates range from 50% to 80%, indicating genetics play a significant role.
❌
The Cons (DZ & Environment) Concordance rates are lower in dizygotic twins, indicating that environment is also crucial.

Key Candidate Genes

Specific genes linked to vulnerability and traits common in AN:

🧠

Serotonin (5-HTT)

Variations are linked to obsessive-compulsive and anxiety traits common in anorexia.
🍽️

Dopamine-related genes

May affect how individuals respond to food and reward processing.
⚖️

Peptide Genes

Regulate appetite-stimulating or suppressing peptides (Orexigenic and anorexigenic).

Neural Explanations Checklist

Neuroimaging and neurobiological studies have identified key brain differences.

✓

Hypothalamic Dysfunction

Could contribute to impaired hunger signalling and abnormal appetite in anorexia.
✓

Serotonin (5-HT)

Altered activity related to mood regulation, anxiety, and satiety.
✓

Dopamine

Abnormal function may contribute to altered reward processing, making food less pleasurable.

Brain Structural Findings

Structural MRI findings frequently highlight deficits in key cortical areas:

Reduced Grey Matter Volume
Often reported in specific areas (e.g., frontal lobes, parietal lobes) which may relate to poor cognitive flexibility, body image distortions, and control over eating.

Cognitive Control and Interoception

💡

Functional brain imaging shows altered activity in the insula (important for body awareness and hunger signals) and prefrontal cortex (involved in self-control and decision-making). This may explain rigid control over food intake and distorted body image perceptions.

Conclusion: Interactionist View

Key Takeaway

Biological explanations suggest a genetic predisposition combined with brain abnormalities in appetite regulation and reward systems increase vulnerability to anorexia nervosa. These biological factors interact with psychological and environmental influences to result in the disorder.
```
Biological Explanations of Anorexia Nervosa
Term
What is anorexia nervosa?

What is anorexia nervosa?

Answer
Definition

A serious eating disorder characterized by intense fear of gaining weight, distorted body image, and severe food restriction leading to underweight status.

Term
Biological explanations focus on?

What do biological explanations of anorexia nervosa focus on?

Answer
Focus

Genetic predispositions and neural abnormalities contributing to the disorder's development and maintenance.

Term
Twin studies reveal?

What do twin studies reveal about anorexia nervosa?

Answer
Findings

Higher concordance rates in monozygotic twins compared to dizygotic twins, suggesting heritability estimates of 50%-80%.

Term
Family studies show?

How do family studies support genetic vulnerability in anorexia?

Answer
Support

Relatives of anorexia patients have increased risks of the disorder and related psychopathologies.

Term
Candidate genes linked?

Which candidate genes are linked to anorexia nervosa?

Answer
Genes

Serotonin transporter genes (5-HTT), dopamine-related genes, and orexigenic/anorexigenic peptide genes.

Term
Hypothalamus role?

What role does the hypothalamus play in anorexia nervosa?

Answer
Function

Possible hypothalamic dysfunction impairs hunger signaling and appetite regulation.

Term
Serotonin abnormalities?

How are serotonin abnormalities related to anorexia nervosa?

Answer
Impact

Altered serotonin activity affects mood, anxiety, and appetite, increasing anxiety and obsessive behaviors.

Term
Dopamine impact?

What impact does dopamine have in anorexia nervosa?

Answer
Effect

Dopamine abnormalities alter reward processing, reducing pleasure from food and increasing reward from restriction.

Term
Brain structural changes?

Which brain structural changes are seen in anorexia nervosa patients?

Answer
Changes

Reduced grey matter volume in frontal and parietal lobes, affecting cognitive flexibility and body image.

Term
Cognitive control and interoception?

How do cognitive control and interoception impairments contribute to anorexia?

Answer
Contribution

Altered insula and prefrontal cortex activity cause rigid food control and distorted body perceptions.

Term
Overall biological perspective?

What is the overall biological perspective on anorexia nervosa?

Answer
Summary

Genetic predisposition combined with brain abnormalities increase vulnerability, interacting with psychological and environmental factors.

Tip: Tap a card to flip. Shuffle or Reset anytime.

🧠 Anorexia Nervosa Genetics & Neuroscience Quiz

1. What type of twin study evidence supports the genetic basis for anorexia nervosa?

Monozygotic twins share more genes and show higher concordance, indicating a strong genetic component.

2. Which neurotransmitter is associated with increased anxiety and obsessive behaviors in anorexia nervosa?

Altered serotonin function affects mood regulation and anxiety, common in anorexia nervosa.

3. What brain area is involved in regulating hunger and may show dysfunction in anorexia nervosa?

The hypothalamus controls hunger signals and energy balance, and its dysfunction may reduce appetite drive.

4. Which gene type has NOT been linked to anorexia nervosa?

Genes related to neurotransmitters and appetite regulation are implicated, but not muscle protein genes.

5. Reduced grey matter volume in which brain lobes is associated with anorexia nervosa?

Reductions in frontal and parietal lobe grey matter relate to cognitive inflexibility and body distortions.

📊 Results

  • Notes and Quiz
  • Psychology
  • AS & A Level
  • Eating Disorders
  • AQA