Schizophrenia: Contemporary Study (Carlsson et al 1999)

Question 1

What were the aims of this contemporary study?

Answer 1

• To review studies into the relationship between dopamine and glutamate on the symptoms of schizophrenia
• To explore glutamatergic deficiency which is a rival theory of the dopamine hypothesis

Question 2

Define ‘glutamate’.

Answer 2

A neurotransmitter nerve cells use to send messages to other nerve cells that controls memory and learning.

Question 3

What was used in the sample?

Answer 3

32 studies investigating neurochemical levels in patients with schizophrenia.

Question 4

What type of method was used?

Answer 4

Literature review

Question 5

Briefly describe the procedure of this contemporary study.

Answer 5

• Reviewed 32 pieces of research into the relationship between neurotransmitters and schizophrenia
• Considered evidence from studies on the use of recreational drugs known to induce psychosis and studies into the effectiveness of drugs used to treat schizophrenia and their method of action on the brain

Question 6

What were the 3 parts to the results of Carlsson’s study?

Answer 6

1) Dopamine as an explanation for schizophrenia
2) Glutamate as an explanation for schizophrenia
3) Drug treatments

Question 7

Briefly describe the first part of the results.

Answer 7

1) Dopamine as an explanation for schizophrenia
- Evidence from PET scans support the dopamine hypothesis as patients with SZ showed more dopamine activity than a healthy control group - especially in the basal ganglia

Question 8

Briefly describe the second part of the results.

Answer 8

2) Glutamate as an explanation for schizophrenia
- Evidence supports the role of hypoglutamergia in the development of psychotic symptoms
Miller and Abercrombie (1996) show that the release of dopamine is increased if glutamate activity is reduced through blocking NMDA receptors with PCP
- Glutamate failure in the cerebral cortex may lead to negative symptoms whereas failure in the basal ganglia may lead to positive symptoms

Question 9

Briefly describe the third part of the results.

Answer 9

3) Drug treatments
- Some patients respond better to some drugs than others which could be due to some people’s SZ being more dopaminergic than others
- Those who are more resistant to antipsychotics may have a more glutamatergic condition whereby the drug clozapine is supposed to help due to targeting serotonin instead and it is highly effective on ‘untreatable patients’ with limited side effects

Question 10

Describe the conclusion of this contemporary study.

Answer 10

• Carlsson concluded that further research is needed in developing drugs to treat schizophrenia that avoid negative side effects
• This should be done by considering more neurotransmitters than dopamine in the development of the disorder
• Schizophrenia may have different types that could be caused by different neurotransmitters

Question 11

Evaluate the generalisablity using a high and low point.

Answer 11

P - High
E - Used 32 pieces of research looking at the different types of schizophrenia
E - Therefore this represents all/most patients with schizophrenia
P - Low
E - Study uses research from 20 years ago where data would be ‘time-locked’ to that era’s society where behaviour of schizophrenia
E - Therefore it would not represent people with schizophrenia and their symptoms today

Question 12

Evaluate the reliability using 2 high points.

Answer 12

P - High
E - Studies used PET scans
E - Data is scientific, objective and easily comparable
P - High
E - Secondary data of 32 studies allows for high quantity of findings
E - Therefore there is more to compare for consistency

Question 13

Are there any applications?

Answer 13

P - Yes
E - Showed that there are potentially more neurotransmitters such as serotonin involved in the development of schizophrenia
E - Therefore drugs can be developed to tackle different types and different symptoms, including negative ones

Question 14

Evaluate the validity using a high and low point.

Answer 14

P - High
E - Looked at the wide spectrum of different types of schizophrenia and whether or not it was in remission
E - Therefore findings have more credibility due to the volume
P - Low
E - Secondary data of 32 studies that involve animal research
E - Wouldn’t know about subjectivity or researcher bias in whether the animals were actually displaying symptoms of schizophrenia which decreases credibility

Question 15

Evaluate the ethics using 2 high points.

Answer 15

P - Good
E - Uses secondary data from 32 other studies in the public domain
E - Therefore no ethical considerations to be made and no ethical guidelines broken
P - Good
E - Uses animals in research
E - More ethical to use for extensive research with things such as drugs than humans

Question 16

Briefly describe what past studies included

Answer 16

PET scans used on SZ patients to show relationship between dopamine and glutamate

Animal research used to show the link between dopamine and glutamate and symptoms of SZ (and for seeing effect of amphetamines, and treatment drugs)