bio explanation of anorexia

Unit 4 Clinical Psychology
7) Anorexia Biological explanation
Homework check
• Homework check – you should have
considered the learning (behavioural)
explanation for anorexia nervosa.
• Let’s look at another explanation…
Learning outcomes
1) Describe and evaluate the biological explanation of
anorexia nervosa.
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
• 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 overeating or starvation in the animals.
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 overeating in others. For anorexics it is as if their
VMH is jammed on.
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.
• Evaluate the biological approach
explanations for anorexia nervosa.
And finally…
• Homework – research rational Emotive
therapy as a therapy for someone
suffering from anorexia nervosa.