Anorexia - biological explaination Flashcards
what is the biological explanation for AN?
genetic explanation
identified genetic variants linked to AN - EPHX2 gene, and the ITPR3 gene
genes and neurotransmitters
EPHX2 gene:
codes for the enzyme epoxide hydrolase - regulates cholesterol metabolism (AN = high levels of cholesterol)
Ashley Scott-Van Zeeland (2014) - compared AN + control patients, EPHX2 significantly linked with AN
ITPR3 gene:
Encodes protein which is a receptor for inositol triphosphate - involved in detecting taste
Don’t have motivation for eating
Linked to AN in same study
how do genes effect neurotransmitters?
dopamine
serotonin
genes and dopamine
DAT1 gene codes for protein called the dopamine transporter - embedded in the membrane of presynaptic neurons + regulates the transport of dopamine between the neuron and synaptic cleft
mutation disrupts process > abnormally high amounts of dopamine for synaptic transfusion > disrupts brain’s award process
genes and serotonin
5HTR2A gene codes for a subtype of postsynaptic serotonin receptor called the 5-HT2A receptor
mutation effects the 2A receptor - less binding between serotonin + receptor - appetite related neural info isn’t transmitted normally
evaluation points of the genetic/biological explanation of AN
research support
equal environments assumption + competing argument
anorexia is polygenic
application to prevention + treatments
evaluation of genetic explanation of AN - research support
from twin studies
Holland et al - study of 45 pairs of female twins: 56% concordance rate for MZ and 5% for DZ
confirmed by Treasure & Holland - 65% MZ, 32% DZ
supports genetic influences
evaluation of genetic explanation of AN - equal environments assumption
to compare concordance rates, need to assume MZ + DZ twins are treated with equal degrees of similarity
Jay Joseph - argues MZ twins are treated more similarly
greater environmental similarity = heritability estimates are inflated + genetic influences aren’t as great as twin studies suggest
evaluation of genetic explanation of AN - equal environments assumption - competing arguments
little evidence that the equal environments assumption is violated in twin studies (Thornton et al 2010)
key issue = is treating more similarly cause of AN
Kelly Klump - MZ twins aren’y more likely to have similar results towards eating
evaluation of genetic explanation of AN - anorexia is polygenic
cannot be explained solely by a single gene
genes make modest but important contributions
true cause os highly complex - any explanation risks oversimplification
evaluation of genetic explanation of AN - application to prevention + treatments
understanding of genetic basis leads to useful developments in prevention + treatments
treatment to be targeted more effectively
can improve quality of life, reduce stress + avoid needless deaths
