Schizophrenia Lesson 4: Biological Explanation For Schizophrenia - Genetics

Question 1

What is the study Ripke et al?

Answer 1

Ripke suggested that schizophrenia might be polygenic; whereby a number of candidate genes might be responsible for causing the illness
He did a meta-analysis or studies that looked at candidate genes and schizophrenia sufferers
37,000 schizophrenia sufferers were investigated and compared to 11,000 controls
He found that 108 separate genetic variations were associated with increased risk of getting schizophrenia
These genes seemed to code for the functioning of the neurotransmitter dopamine
High levels of dopamine can cause schizophrenia

Question 2

Evaluation for the study by Ripke (summary)

Answer 2

1. Complete ignores other approaches in explaining the causes schizophrenia
2. Diathesis stress model
3. Overwhelming evidence that genetics is the cause of schizophrenia
4. Schizophrenia can sometimes occur in the absence of genetics or family history
5. Dopamine hypothesis

Question 3

Ripke - evaluation point 1: Complete ignores other approaches in explaining the causes schizophrenia -

Answer 3

Other approaches in psychology need to be examined in terms of what could cause schizophrenia
E.g. the behavioural model might suggest that children can learn abnormal behaviours via the environment (classical and operant conditioning and social learning theory) and therefore this could help develop schizophrenia rather than genetics

Question 4

Ripke - evaluation point 2: Diathesis stress model -

Answer 4

Genetics does not offer a full explanation as to how schizophrenia is transmitted.
Just because someone has the gene for schizophrenia it does not automatically mean that they will get the illness (due to the gene possibly being recessive).
Thendiathesis stress model would suggest the idea that a person is more likely to get schizophrenia if they have the gene for the illness, and then a factor in the environment would trigger the illness (e.g. stress).
This model highlights the importance of the environment and genetics

Question 5

Ripke- evaluation point 3 : Overwhelming evidence that genetics is the cause of schizophrenia +

Answer 5

There is an overwhelming amount of research support from many psychologists that schizophrenia does seem to be caused by genetics. There is evidence from Gottesman, Kety and many other psychologists which makes the evidence robust and hard to ignore
Therefore genetics can not be ignored as a major cause of schizophrenia

Question 6

Ripke - evaluation point 4: Schizophrenia can sometimes occur in the absence of genetics or family history -

Answer 6

Sometimes schizophrenia can occur in the absence of genetics or family history
There could be a mutation on parental DNA that causes schizophrenia in their further offspring (e.gl speed cell damage via radiation, poison or a viral infection).
There is also a positive correlation between the parental age of fathers and the risk of having a schizophrenic child.
0.7% of the father is under the age of 25, which increases to 2% if the father is over the age of 50

Question 7

Ripke - evaluation point 5: dopamine hypothesis +

Answer 7

The research conducted by Ripke can be supported by the dopamine hypothesis which states that high levels of dopamine in the D1 and D2 receptors in the brain can cause schizophrenia.
Ripkes work can be praised for linking together two biological mechanism that could cause schizophrenia: genetics and the link to high dopamine production. Therefore Ripke’s research provides valuable support for the biological approach/model

Question 8

What is the study by Gottesman and Shields on twins and schizophrenia?

Answer 8

• 224 sets of twins from 1948-1993 who appeared on the twin Register were investigated
• 106 sets of twins were MZ and 118 were DZ, 120=male and 104=female
• average age of participants was 46 years of age and the participants came from a range of different ethnic backgrounds
• the study was conducted in London hospital. It was a longitudinal study (over 25 years)
• the study relied on the fact that one twin already had the illness of schizophrenia. Concordance rates were investigated which examined the likelihood or the chances of the healthy twin becoming schizophrenic over time.
  They used:
  a) in-depth interviews b) doctors case notes c) the DSM
  Results
• 48% of MZ twins were both concordance for schizophrenia by the end of the study
• 17% of DZ twins were both concordant for schizophrenia by the end of the study
  This indicates that schizophrenia does have a genetic basis to some extent

Question 9

How many sets of twins were investigated in Gottesman and Shields study on schizophrenia?

Answer 9

224

Question 10

When did the Gottesman and Shields study take place and how long did it last for?

Answer 10

1948-1993

25 years

Question 11

What was the average age of the participants in the Gottesman and Shields study?

Answer 11

46 years of age

Question 12

Evaluation of the Gottesman and Shields study (summary)

Answer 12

1. Longitudinal +
2. Supports the biological approach +
3. Ignores the behavioural approach -
4. Reliable and valid +
5. Relied on interviews -

Question 13

Gottesman and Shields - evaluation point 1: longitudinal +

Answer 13

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 tike to see if they get the illness

Question 14

Gottesman and Shields - evaluation point 2: supports the biological approach +

Answer 14

The research by Gottesman and Shields supports the biological approach as the results show 48% concordance rates for schizophrenia in MZ and 17% concordance in DZ twins.
Therefore the results support the biological argument that schizophrenia can be transmitted via genetics
(Especially considering that the chances of getting schizophrenia is 1% for the general population

Question 15

Gottesman and Shields - evaluation point 4: reliable and valid +

Answer 15

An advantage of the study by Gottesman and shields is that it is both reliable and valid when investigating the genetic cause for schizophrenia
The research diagnosed schizophrenia using in depth interviews, doctors case notes and the DSM
Three different methods were used to diagnose the illness which means that there would have been more chance of inter-rate reliability and higher validity
This gives the research more credibility and strength when investigating the genetic cause of schizophrenia

Question 16

Gottesman and Shields - evaluation point 5: relied in interviews -

Answer 16

The research conducted by Gottesman and Shields could be criticised because it relied on interviews in 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 psychologists and psychiatrists
This might have had a NEGATIVE EFFECT ON THE DIAGNOSIS and classification of schizophrenia (causing delayed or misdiagnosis)