L4 - Genetic Causes Flashcards
What did the twin study by Gottesman and Shields study?
One twin already had SZ
Examined likelihood of the other healthy twin developing it
Chances of MZ and DZ unaffected twin developing schizophrenia? GS
48% for MZ
17% for DZ
How long was the study conducted for? GS
25 yrs
How many twins took part? GS
106 MZ
118 DZ
What were the ethnic backgrounds of the twins? GS
A range
How were the effects measured? GS
Doctors notes
Interviews
Reference to DSM
Positive evaluation point related to the study being longitudinal? GS
Longitudinal so development of illness was tracked to see if healthy twin was worse/same/better than diagnosed one
Positive evaluation of Gottesman study related to validity and reliability
+ Used three different methods to diagnose SZ increasing validity (many ways used to be sure of symptoms) and reliable (inter-rater reliability) so more credibility
Negative of Gottesman study
Ignores behavioural approach
Twins often copy/model each other’s behaviour so may have copied schizophrenic behaviour instead of genetics
Interactions with each other should have been monitored
How many participants involved in the Ripke study?
37000 patients
11000 controls
What type of study was Ripke’s?
Meta-analysis
What were Ripke’s findings?
Found 108 separate genetic variations associated with SZ risk
Genes coded for dopamine
What was the Ripke study hypothesis?
Suggested SZ is polygenic and several candidate genes
Positive evaluation of Ripke
Dopamine hypothesis supports the study as high levels of dopamine in D1/D2 receptors cause SZ
So links genetics and high dopamine and helps support biological approach
Positive evaluation point? R
Other studies support role of genetics
G+S, Kety
Robust, powerful evidence
