BIOCHEMICAL/ POSTMORTEM/ PET SCANS EXPLANATIONS

Question 1

Summarise the biochemical explanation for schizophrenia?

Answer 1

1. Dopamine hypothesis: Schizophrenia is linked to abnormal levels of the neurotransmitter dopamine in the brain.
2. Hyperactivity: Excess dopamine activity in the mesolimbic pathway is associated with positive symptoms (hallucinations/ delusions).
3. Hypoactivity: Reduced dopamine activity in the mesocortical pathway is associated with negative symptoms (avolition, social withdrawal/ cognitive impairments.

Mesolimbic- brain pathway that carries dopamine to areas involved in emotion/ reward.
Mesocortical- carries dopamine to the frontal cortex involved in motivation and thinking.

Question 2

How does research into Broca’s area support the dopamine hypothesis?

Answer 2

• Broca’s region is responsible for language production.
• High dopamine activity in this are has been linked to disorganised or illogical speech (thought disorder) which is a positive symptom of schizophrenia.

Question 3

How to drug trial studies support the dopamine hypothesis?

Answer 3

• Drugs like amphetamine and cocaine, which increase dopamine levels, can trigger hallucinations and delusions.
• This has been seen in both individuals with schizophrenia and healthy participants.

Question 4

How does Lindstrom et al’s (1999) research into Parkinson & L-Dopa support the dopamien hypothesis (link between schizophrenia and dopamine) ?

Answer 4

• Parkinson’s patients are treated with L-dopa, a synthetic form of dopamine.
• When patients given in high doses, they sometimes develop schizophrenia-like symptoms ( hallucinations).

**“Lindström” sounds like “dopamine storm”

Question 5

How do post-morterm studies support the dopamine hypothesis?

Answer 5

Post-mortem studies have found that the brains of deceased individuals with schizophrenia have a larger number of dopamine receptors than non-schizophrenics.

Question 6

Can you give an example of a post-morterm study supporting the dopamien hypothesis?

Answer 6

Wise et al (1974) found that brain fluid from deceased schizophrenic patients had abnormally low levels of the enzyme that breaks down dopamine, suggesting the dopamine may have been present in excessive quantities.

Brain link- you only get wise once you’re deceased

Question 7

How to Positron Emission Tomogrophany (PET) scans support the dopamine hypothesis?

Answer 7

PET scans have indicated a greater number of dopamine receptors in the striatum, limbic system and brain cortex in schizophrenics compared none-schizophrenics.

Question 8

Can you name a study PET scan study that supports the dopamine hypothesis?

Answer 8

Nestler (1997): suggests that decreased dopamine activity in the prefrontal cortex of schizophrenic patients may correlate with negative symptoms such as flattened affect.

brain link- dopmaine has nestled in different places

Question 9

Name 1 strength and 1 weakness of the biochemical explanation of schizophrenia?

Answer 9

• Strength= Emperically and scientifically tested through a large body of objective research (Lindstrom et al 1999, Wise et al 1974, Nestler 1997)
• Weaknesses= Biologically reductionist ignoring psychological, cognitive explanations. Not everyone respond to antipsychotics (especially those with negative symptoms, suggesting dopamine isn’t the only factor involved and other factors should be considered.
• Weaknesses= Deterministic: Implies that if someone has excess dopamine activity they WILL develop schizophrenia. This removes responsibility and free will, may lead to pessimism about recovery, non-drug therapies may be undervalued