1. Unit 4 Clinical Psychology
7) Anorexia Biological explanation

2. Homework check
Homework check – you should have mortised the learning (behavioural) explanation for anorexia nervosa.
Let’s look at another explanation…

3. Learning outcomes
1) Describe and evaluate the biological explanation of anorexia nervosa.

9. Biological approach
Assumes our behaviour is controlled by the activity in the CNS, specifically the brain.
The brain itself is organised into regions which have different roles, so a malfunction in one region may cause a behavioural problem in the individual.
Malfunctioning of the hypothalamus plays an important role in the regulation of eating. Animal experiments which involve lesions in a particular part of the hypothalamus have led to either over-eating or starvation in the animals.

10. Biological approach
It is believed that noradrenaline acts on part of the hypothalamus which leads to eating; in contrast, it was found that serotonin suppresses appetite in non-human animals.
This biochemical importance has been used as an explanation for anorexia in humans. The lateral hypothalamus (LH) produces hunger and the ventromedial hypothalamus (VMH) depresses hunger. A malfunction here may be the cause of loss of appetite in some, and over-eating in others. For anorexics it is as if their VMH is jammed on.

11. Biological approach
Another type of biological explanation is that anorexia may run in families, so genetics could play a part.
Research in twins has shown that MZ have a higher concordance rate than DZ twins for anorexia. Holland et al (1984) found a 56% concordance rate in MZ twins, and only 5% in DZ twins.

12. Task Read sheet ‘Anorexia Nervosa – Two Explanations.
Evaluate the biological approach explanations for anorexia nervosa.
Answer the exam question at the bottom of the page.

13. Essay marking Read the essay, Biological eating disorders.
Discuss how many marks out of 12 you think it should get.
Identify where the marks should be given.

14. And finally…
Homework – research rational Emotive therapy as a therapy for someone suffering from anorexia nervosa.