Biological Explanation Of Anorexia

Question 1

Explain the role of the EPHX2 gene in anorexia

Answer 1

-codes for an enzyme that regulates cholesterol metabolism and impacts the thalamus
-many people during actuate phase of AN have abnormally high levels of cholesterol
-link is that an inherited variant of this gene causes over activity of enzyme disrupting cholesterol levels, and the thalamus is linked to serotonin causing anxiety and depression

Question 2

Explain the role of the ITPR3 gene in anorexia

Answer 2

-encodes for a protein which is involved in detecting tastes such as sweet and bitter
-a genetically determined dysfunction of the taste pathway means people with AN are indifferentiated to tastes that other people enjoy and partly motivates eating
-this therefore explains the skipping of meals or calorie counting as do not enjoy eating

Question 3

Explain the role of the DAT1 gene in anorexia

Answer 3

-codes for a protein called the dopamine transporter
-a mutation of this gene would leave abnormally high amounts of dopamine available for synaptic transmission, dysregulating the brains reward systems so ratings normal motivating rewarding function is impaired
-this will result in the skipping of meals, calorie counting and self induced vomiting

Question 4

Explain why anorexia being a polygenic disorder can cause anorexia

Answer 4

-polygenic disorder means no single gene can explain all the symptoms of anorexia
-Taq A1 allele gene is present in AN suffers and is linked to addiction
-this could explain the obsessive symptoms of AN such as perfectionism, frequent weighing, calorie counting, over exercising

Question 5

Explain the role of 5-HTR2A in anorexia

Answer 5

-mutation in this gene affects the structure of the 2A receptor which lowers binding of serotonin with the receptor
-this means appetite related neural information is not transmitted normally
-this may lead to skipping meals, self induced vomiting etc

Question 6

Explain why anorexia has high heritability and why this may be a biological cause

Answer 6

-heritability is the likelihood of the condition being passed down genetically through relatives
-family studies look at the first degree of relatives of people with and without eating disorders in order to establish a heritability estimate, which is currently 70%
-the closer the relative the higher the risk
-children with AN parents are 10 times more likely to develop it themselves because of this high heritability rate

Question 7

Explain how adoption studies can show biological cause of anorexia

Answer 7

-when biological twins (MZ or DZ) are separated being adopted into 2 different environments
-this allows for biological factors and environmental factors to be separated
-this can show how much anorexia is biologically caused through establishing a concordance rate (agreement) as the environment is no longer controlled as well between the twins