Carlsson et al (1999)

Question 1

Aims?

Answer 1

• To review studies that show the relationship between SZ and dopaminergic dysfunction
• To explore glutamatergic deficiency
• To use their understanding to produce a new anti-psychotic drug that has fewer side effects

Question 2

Procedure?

Answer 2

• Conducted a meta-analysis, using 32 pieces of previous research
• Completed a literature review
• The previous research that was analysed came from a range of areas - using animals, SZ’s and patients with Parkinson’s/Huntington’s (PET scans)
• The animal research was used to show the impact of recreational drugs on reducing glutamate levels in the brain to show SZ like symptoms

Question 3

What were the 4 parts to the results of Carlsson’s study?

Answer 3

1) Dopamine as an explanation for schizophrenia
2) Glutamate as an explanation for schizophrenia
3) Glutamate and dopamine interaction
4) Drug treatments

Question 4

Briefly describe the first part of the results

Answer 4

1) Dopamine as an explanation for schizophrenia
- SZ patients showed more dopamine activity than a healthy control group, especially in basal ganglia
- However, Laruelle et al found that SZ patients in remission had normal dopamine activity - suggests that high dopamine levels were a symptom of SZ and not a cause

Question 5

Briefly describe the second part of the results

Answer 5

2) Glutamate as an explanation for schizophrenia
- PCP acts as a glutamate antagonist, blocking glutamate receptors
- PCP leads to psychosis
- Questions whether glutamate deficiency has a role in psychosis
- Glutamate failure in cerebral cortex = negative symptoms
- Glutamate failure in basal ganglia = positive symptoms

Question 6

Briefly describe the third part of the results

Answer 6

3) Glutamate and dopamine interaction
- Dopamine receptors are affected by glutamatergic neurons acting as accelerators/brakes
- Glutamate and dopamine interact; reduced glutamate functioning = increased dopamine release

Question 7

Briefly describe the fourth part of the results

Answer 7

4) Drug treatments

- Clozapine is highly effective with less side effects

Question 8

Conclusions?

Answer 8

• Carlsson suspects there a probably different groups of SZ patients whose symptoms have different biological explanations
• Researchers should start looking at other neurotransmitters, like GABA and acetylcholine

Question 9

Strength?

Answer 9

P- Reliable
E- The studies cited are all lab experiments, which use PET scans
E- These techniques are standardised and replicable, making the research reliable

Question 10

Weakness?

Answer 10

P- Unreliable
E- Reliance on secondary data from a variety of sources
E- There is no way of knowing how reliable the original studies were. Therefore, basing conclusions about treatments on this research could be problematic

Question 11

Strength?

Answer 11

P- Valid
E - Use of secondary data allowed a great deal of research to be brought together quickly, providing an overview. The research is from a range of areas - animal studies, SZ’s and patients with Parkinson’s/Huntington’s
E- This mass information allows for more valid conclusions to be drawn and gives depth

Question 12

Weakness?

Answer 12

P- Invalid
E- Previous studies used animals. Human behaviour and response to drugs would be much more complex than animals, despite sharing similar brain structures
E- Studies may lack generalisability and therefore reduces the credibility of the study based on the chosen secondary research