3/ Eating Behaviours - Biological explanations for anorexia

Question 1

what two things are included in the biological explanations for anorexia?

Answer 1

1. genetic

2. neural - serotonin and dopamine

Question 2

explain what is meant by the genetic explanation for anorexia.

Answer 2

assumes the condition is inherited from parents the same way hair colour is.

Question 3

what % rate is anorexia heritability?

Answer 3

60%

Question 4

what candidate gene is known to cause anorexia?

Answer 4

Ephx2 - involved in cholesterol metabolism and people with severe anorexia have abnormally high levels of cholesterol.

Question 5

what research is there to support the genetic explanation contribution to anorexia? %%

Answer 5

MZ twins - 56%

DZ twins - 5% however same study 7 years later found -MZ twins 65% and- DZ 32% – unreliable data.

Question 6

why cannot we draw from conclusions from twin studies in the genetic explanation?

Answer 6

the concordance rates are never 100% for MZ twins therefore genes cannot be the sole explanation for anorexia. Also MZ twins are raised and treated the same, more then DZ - may explain some of the data.

Question 7

why might the genetic explanation by slightly simplistic?

Answer 7

anorexia is characterised by a wide range of psychological and physical symptoms that cannot just come from ONE gene. – multiple genes need to be involved, therefore it is a polygenic disorder.

Question 8

why can’t genetic explanations offer a satisfactory explanation for anorexia?

Answer 8

1. can’t explain why its more common in females
2. why it has increased in recent years – e.g. in Japan it never existed but has shown greater incidence in girls who read magazines portraying idealised thin bodies.

Question 9

how does the neural explanation serotonin affect anorexia?

Answer 9

• research shows lower levels of serotonin = anorexia and serotonin levels return to normal after short term weight gain.

Question 10

what is the main strength for serotonin contribution to anorexia?

Answer 10

practical application - drug therapy, SSRIs (increase serotonin) which helps relieve anorexic symptoms.

Question 11

what is a weakness of serotonin explaining anorexia?

Answer 11

• drugs that increase serotonin are not wholly effective - no difference in pps taking SSRIs to a matched control group.

Question 12

what research has shown us that high levels of serotonin rather than low contribute to anorexia?

Answer 12

fMRI scans have shown increase in serotonin activity in several areas of females brain who had recovered from anorexia compared to female control group.

Question 13

how does dopamine contribute to anorexia?

Answer 13

raised levels - creates pleasure feelings when eating but do not create these for anorexic patients.

Question 14

what research can support the effects of dopamine?

Answer 14

blinking is associated with high levels of dopamine - study found increased rates of blinking in people with anorexia compared to a control group

Question 15

why does the dopamine explanation lack reliability?

Answer 15

other studies have found reduced levels of dopamine rather than high contribute to anorexia.

Question 16

overall, what may be a better explanation of anorexia?

Answer 16

diathesis stress model - comes about both through genes and the environment. e.g. a gene creates vulnerability to anorexia but will only by expressed with the addition of a environmental stressor - provides a more holistic approach.