Schizophrenia: Neurotransmitter Explanation

Question 1

Why is schizophrenia attributed to excess dopamine (hyperdopaminergia)?

Answer 1

Antipsychotic drugs chlorpromazine and reserpine help symptoms of schizophrenia, but also induce side effects of tremors and muscle rigidity.

These are symptoms of Parkinson’s disease (low dopamine) - so schizophrenia was linked to high dopamine.

Question 1

Who attributed schizophrenia to dopamine deficiency (hypodopaminergia)?

Answer 1

Davis et al. (1991) suggest that:
* Positive symptoms of schizophrenia (e.g. delusions and hallucinations) may result from excess dopaminergic activity in the mesolimbic pathway.

• Negative symptoms (e.g. flat affect and mutism) may result from a lack of dopamine activity in the mesocortical pathway.

Question 2

What role does serotonin play?

Answer 2

Clozapine binds to serotonin receptors and reduces positive and negative symptoms of schizophrenia - so symptoms may be caused by irregular seretonin activity.

Question 3

What is a strength of the neurotransmitter explanation of schizophrenia? (hint: rats and meth…)

Answer 3

A strength of the neurotransmitter explanation is that it has animal research supporting it.

Tenn et al (2003) gave rats amphetamine injections (which increase dopamine release) that caused them to show schizophrenia-like symptoms.

This suggests that increased dopamine levels may cause schizophrenia symptoms in humans.

Question 4

What is a weakness of the neurotransmitter explanation of schizophrenia? (hint: prevalence in cultures)

Answer 4

A weakness of of the neurotransmitter explanation is that it cannot explain the prevalence in 2nd generation immigrants.

Veling et al (2008) showed that Moroccan immigrants were more likely to be diagnosed with schizophrenia than Turkish immigrants. This was correlated with the discrimination facd by each group.

This suggests that environmental factors (social stress) increases the chances of having schizophrenia, so it isn’t purely genetic.

Question 5

What is an application of the neurotransmitter explanation of schizophrenia? (hint: drug treatments)

Answer 5

An application of the neurotransmitter explanation is that it has led to drug treatments.

Research shows that dopamine antagonists (dopamine receptor blockers) can reduce positive symptoms.
Drugs such as Clozapine have also been successful in reducing both positive and negative symptoms.

This means that, through the understanding of neurotransmitters, those with schizophrenia can live with their symptoms being controlled.