Download ACTIVITY - BIOLOGICAL EXPLANATIONS OF ANOREXIA

Biological explanations of Anorexia nervosa
Evolutionary approach
Briefly outline Guisinger’s ‘flee famine’ hypothesis (use the words: adaptive, survival, and if
you can, use the following words as well – innate, gene pool, )
The evolutionary explanation of anorexia nervosa is difficult to
because it is a
post-hoc explanation in that it attempts to explain something after it has occurred. It is impossible go
back in time to carry out scientific research and so the theory is u s _ _ _ _ _ _ _ _ _ _.
Furthermore, it doesn’t explain why anorexia afflicts far more _ _ _ _ _ than _ _ _. It would seem
reasonable to assume that it would be advantageous to both.
Genetic explanations of eating disorders
Anorexia nervosa occurs within families across generations but this doesn’t prove that it is due to
genes because.....
A better approach than just looking at the occurrence of eating disorders in families is comparing the
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ of MZ twins with DZ twins.
Briefly explain why this is a useful way of investigating the strength of genetic influences in
anorexia nervosa.
Holland et al 1984 found the following concordance rates for anorexia nervosa:
MZ twins =
DZ twins =
This suggests that there is a genetic p _ _ _ _ _ _ _ _ _ _ _ _ _ for anorexia nervosa. What does this
mean?
Discuss these concordance rates more fully (i.e. why do we have to conclude that there must
be other factors involved apart from genetic ones? How can environmental influences be
responsible for higher concordance rates in MZ twins?)
Discuss some of the methodological issues involved in comparing MZ twins with DZ twins for
anorexia nervosa (e.g. availability of sample, validity, reliability, cultural bias)
Neural factors
Early studies found a reduction in levels of 5-HIAA in people with eating disorders. Which
neurotransmitter does this affect and in what way (i.e. over- or under-activity)?
The problem with these early studies was that the participants used currently suffered from anorexia
nervosa and it was impossible to tell if the reduction in 5-HIAA was a cause or an effect of the
disorder. Malnourishment and starvation can bring about significant changes in the body and brain
and it is possible that s_ _ _ _ _ _ _ _ is affected by this rather than the other way round.
PET scans have made it possible to study activity directly in the brain and are easy to use with
anyone. People who have recovered from eating disorders can easily be studied in this way and PET
scans show that they also have a reduction in the 5-HIAA metabolites. Nevertheless, it is still not
possible to claim that reduced serotonin activity causes anorexia nervosa. Explain why not.
Briefly, explain what is meant by an integrated approach and why it is desirable.