Carlsson

  • Created by: debbieo01
  • Created on: 06-11-18 21:14
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  • Carlsson et al. 1999
    • Aim
      • Review studies into the relationship between schizophrenia and levels of neurotransmitters, especially dopamine and glutamate.
    • Procedure
      • Reviewed research from a variety of sources that investigated neurochemical levels in patients with schizophrenia
      • Also studies into drugs known to induce psychosis and evidence from studies on the use of recreational drugs known to induce psychosis.
      • Used 33 studies and took part in 14
      • PET scans on animals
    • Results
      • Schizophrenic patients show more dopamine activity than a healthy control group in the basal ganglia.
        • Laruelle et al. 1999 found that schizophrenia patients in remission had normal dopamine activity.
      • Glutamate seems to regulate the behaviour of dopamine. Carlsson says it acts as an accelerator by increasing dopamine activity or as a brake, by decreasing it.
        • Miller and Abercrombie 1996 show that the release of dopamine is increased if glutamate activity is reduced by blocking NMDA receptors.
    • Conclusion
      • Further research needs to be conducted into developing drugs that treat schizophrenia whilst avoiding negative side effects, possibly by considering other neurotransmitters involved. Considering all of the evidence, researchers suggest that sz may have different types caused by different neurotransmitters.
  • Lodge et al. 1989 claims that glutamate activity at NMDA receptors produces psychotic reactions in rats and humans.
    • Drugs like PCP and ketamine produce psychotic symptoms, but instead of activating dopamine, they stimulate glutamate receptors called NMDA.
  • Generalisable as he used 33 studies and took part in 14, which were a very representative selection of what was going on at that time.
    • However it was done in 1999, two decades ago. This study may be time locked if researched has moved on since then and it is no longer representative
  • However, Laruelle et al. was unpublished at the time and therefore hadn't been peer reviewed.
    • The studies were all lab experiments, many of them on animals, which used modern PET scanning techniques. This is standardised and replicable.
  • The main application of this study is in the development of new antipsychotic drugs.
  • Carlsson questions the validity of the dopamine hypothesis. He lists some of the evidence that has called it into question such as the new atypical antipsychotics like clozapine which reduces psychotic sypmtoms without influencing dopamine. He considers an alternative - the glutamate hypothesis.
  • No direct ethical issues, however many studies involved animals being injected with drugs.

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