Carlsson published a review to investigate the
therapeutic implications from research on
schizophrenia
AIM
To investigate further the relationship
between levels of neurotransmitters on
symptoms of schizophrenia
She believed that dopamine may not b the only
neurotransmitter related to schizophrenia
METHOD
Looked at studies investigating neurochemical
levels in patients
Evidence for high levels of dopamine inducing symptoms of psychosis from
brain scans.
Looked at studies into drugs known to induce symptoms of
psychosis
Evidence that linked amphetamines (which increase dopamine levels) to
schizophrenia
FINDINGS
The neurotransmitter glutamate failing to be
transmitted in cereal cortex related to negative
symptoms
Glutamate failure in basal ganglia relates to positive symptoms
Clozapine is very effective at blocking activity of dopamine and serotonin. There is also
fewer side effects
CONCLUSION
Schizophrenia may have different types that could be caused by abnormal levels of
different neurotransmitters, and not just dopamine
Further research is needed to develop drugs that avoid negative side effects
EVALUATION
GENERALISABILITY
However, that time was 2000, nearly two decades ago. This
study may be "time-locked" if research has moved on since
then and it is no longer representative of the state of
scientific ideas today.
RELIABILITY
The studies Carlsson et al. cite are all lab experiments,
many of them on animals, which use modern PET or
SPECT brain imaging techniques. These techniques are
standardised and replicable, making the research
reliable.
APPLICATION
The main application of this study is in the
development of new antipsychotic drugs - improved
dopaminergic drugs that have fewer side-effects based
on a better understanding of dopamine pathways
VALIDITY
Carlsson is questioning the validity of the
Dopamine Hypothesis. He also considers
the Glutamate hypothesis
ETHICS
This is a review study so there are no ethical
issues directly connected to it.
BUT, many of the studies Carlsson et al. cite are animal studies involving lab mice. These might involve
ethical issues, since the mice are being injected with drugs to bring on psychotic symptoms.