Lesson 4: Biological explanation for schizophrenia – Genetics Flashcards
What 2 studies looked into the genetic causes of schizophrenia?
1) Ripke et al- meta analysis
2) Gottesman and Shields- twins 👯♂️ and schizophrenia
What did Ripke et al do?
Ripke suggested that schizophrenia polygenic (number of candidate genes responsible for causing illness)
Did meta-analysis of studies that looked at candidate genes and schizophrenia sufferers- compared to control group
What were the findings of Ripke et al’s study?
Found 108 separate genetic variations associated with ⬆️ risk of getting schizophrenia- genes 🧬 coded for functioning of dopamine
⬆️ levels of dopamine-> schizophrenia
What are the evaluation points of Ripke et al’s study?
👎- Although genetics 🧬 has a great deal of support, we must be cautious when looking at 🧬 alone as a cause for schizophrenia- other approaches in Psychology need to be examined e.g. behavioural 🏃♂️ model suggests 👶 can learn abnormal 🏃♂️ via environment (classical and operant conditioning and social learning theory)
👎- Just because someone has gene for schizophrenia, ✖️ automatically mean they will get illness (gene possibly recessive)- diathesis stress model would advocate idea that person ⬆️ likely to get schizophrenia if they have gene 🧬 for illness AND factor in environment will trigger illness (e.g. stress)
👍- lots of research support from many psychologists that schizophrenia caused by genetics- evidence from Gottesman, Ripke and many other psychologists
What did Gottesman and Shields do?
Investigated sets of twins (106 sets of twins were MZ and 118 were DZ)- done in London hospital 🏥- longitudinal study- over 25 years
Study relied on fact that 1 twin already had illness of schizophrenia, and concordance rates investigated (examined likelihood of healthy twin becoming schizophrenic)
Methods used included:
1) In depth interviews
2) Doctors case notes
3) The DSM
What were the findings of Gottesman and Shields study?
48% of MZ twins 👯♂️ both concordant for schizophrenia
17% of DZ twins were both concordant for schizophrenia
… schizophrenia does have genetic basis to some extent- especially for MZ twins
genetics less prominent for DZ twins as a cause for schizophrenia (BUT risk still ⬆️ than for general population which is 1%)
What are the evaluation points of Gottesman and Shields study?
👍- A strength of Gottesman and Shields study is that it was longitudinal. This means that the schizophrenic patients could be tracked over long periods of time in order to monitor the development of the illness schizophrenia. This means that longitudinal studies are very valuable when investigating whether schizophrenia is caused by genetics, as patients can be studied over long periods of time to see if they get the illness (+)
👍- The research by Gottesman and Shields supports the biological (genetics) approach as the results show 48% concordance rates for schizophrenia in MZ twins and 17% concordance in DZ twins. Therefore the results support the biological argument that schizophrenia can be transmitted by genetics, (especially since the chances of getting schizophrenia is 1% for the general population). (+)
👎- The research by Gottesman and Shields ignores the behavioural approach when examining the causes of schizophrenia. Identical twins often copy and model each other’s behaviour, so it could be that the healthy twin has modelled or copied schizophrenic behaviour rather than getting the illness via genetics. Therefore we must investigate fully whether the healthy twin gained schizophrenia via genetics or from observing and copying maladaptive behaviour that lead to schizophrenia (-)
👍- The research by Gottesman and Shields has the advantage of being both reliable and valid when investigating the genetic cause for schizophrenia. The research diagnosed schizophrenia using in depth interviews, doctor case notes and the DSM. Therefore there were three different methods that were used to diagnose the illness which means that there would have been more chance of inter-rater reliability and higher validity (really measuring the diagnosis of schizophrenia), which gives the research more credibility and strength when investigating the genetic causes of schizophrenia. (+)
👎- The research conducted by Gottesman and Shields could be criticised because it relied on interviews with patients. Schizophrenia patients often have difficulty with their speech and communication and therefore some patients might have found it difficult to communicate their symptoms effectively to the psychologists/psychiatrists. Therefore this issue could have had a negative effect on the diagnosis and classification of schizophrenia e.g. could have delayed the diagnosis or led to misdiagnosis in some cases. Therefore interviewing patients is a problem, but could be improved by having a range of interviewers who could then correlate their findings to ensure that a correct diagnosis of schizophrenia was given (-)
