Bio S- Genetic Flashcards
Why are twin studies used for research?
MZ share 100% genes and DZ twins share 50%
If it was genetic you would expect that if one twin got it, the other would
What are the twin studies for S?
Gottesman and Shields 72 and 76
What did Gottesman and Shields 72?
Examined the medical records of 57 twins betweeen 1948 and 64
23 MZ and 34 DZ
If twin did not have S they were followed for following 13 years
Found that 42% likelihood of MZ twins developing S compared to 9% DZ twins
What did Gottesman and Shields 76 do?
Meta- analysis of 5 studies reported concordance rates of 75% and 91% for twins with severe form of S
Why are adoption studies used?
If an adoptees have a bio parent with S you’d exoect them to develop it regardless of environment
Who is the researcher for adoption studies?
Tiernari
finnish adoption study
What did tiernari do?
Followed 155 adoptees that were born schizophrenic mothers
in adulthood over 10% of adoptees with bio scizoprenic mothers had developed the disorder
Why were family studies used?
They share some genes so you would expect there to be an increased likelihood
Who are the researchers for family studies?
Kendlers
Parmas
What did Kendler do?
first degree relatives of S were 18 ties more likely to develop the disorder
What did Parmas do?
Followed 207 children who had schizoprenic mothers at a 27 follow up 16% had been diagnosed with S compared to 2% low risk group
Eval for genetic?
Too simplistic
Methodological issues with twin studies
Methodological issues with adoption studies
Could be both genes and environment
Research suggest that genes cannot be the only factor in S
Methodological issues
Why are there methodological issues with twin studies?
it may be exposure to same environment. Similar environment, treated the same
Why are there methodological issues of adoption studies?
The contamination effect- adoptees are exposed to their biological parents with S prior to adoption and as a result it may influence their development of S
Furthermore stress of adoption process play a role eg feeling unwanted and unloved may play a role in development of S
How can it be explained by genes and environment?
Diathesis stress-
bio suggests S is transmitted through genees
D-S model suggests that genetics plays a role but only in the sense that they may make someone more vulnerable to S and that aspects of environment acts as a trigger
biology loads the gun, environment pulls the trigger
