Biological Explanations for SZ: Neural Correlates, Dopamine Hypothesis

Question 1

Neural correlates
- intro

Answer 1

Another biological explanation of schizophrenia is neural correlates.

Idea that the experience of a mental illness (SZ) is associated with abnormalities to the structure or function of the brain.

Question 2

Neural correlates (1)

Answer 2

Eg, early research focused on SZs having enlarged ventricles (fluid-filled gaps between brain areas).

Enlarged ventricles associated with damage to central brain areas and the prefrontal cortex, which recent scanning studies have also linked to the disorder.

Question 3

Neural correlates (2)
- Dopamine hypothesis

Answer 3

More modern research focused on the role of biochemicals in the brain being associated with the disorder.

So, the dopamine hypothesis is a NC exp of SZ.

Suggests that positive symptoms of SZ are the result of the overactive transmission of neurotransmitter dopamine.

SZs have abnormally high numbers of D2 receptors on receiving neurons -> more dopamine binding -> more neurons firing.

Dopamine neurons play a key role in guiding attention, so disturbances in this process may lead to the problems relating to attention, perception and thought found in people with SZ.

Question 4

Neural correlates (3)
- Revised Dopamine hypothesis

Answer 4

In recent years, the dopamine hypothesis has been revised.

Davis and Kahn (1991):
• positive symptoms caused by excess of dopamine in the subcortical areas of the brain (mesolimbic pathway).
• negative symptoms caused by deficit of dopamine in areas of the pre-frontal cortex (mesocortical pathway).

Dopamine has an important but complex role in the development of SZ.

Question 5

Evaluation of neural correlates/dopamine explanation
- STRENGTHS

Answer 5

P) support for DH from drug research
E) Amphetamine drugs are dopamine agonists (stimulate neurons containing dopamine causing the synapse to be flooded with this NT). large doses -> hallucinations and delusions
E) L-dopa (drug used to treat Parkinson’s disease) also works by raising levels of dopamine also the case
L) an excess of dopamine in the brain can explain the onset of positive SZ symptoms

P) DH has practical applications in developing treatments for SZ:
E) Typical antipsychotic drugs used to treat schizophrenia are all dopamine antagonists (work by reducing stimulation of neurons containing dopamine by blocking D2 receptors)
E) in doing so, reduce positive symptoms such as hallucinations and delusions.
L) DH useful in developing treatments that benefit people’s real lives
E) also supports the theory that dopamine overactivity is a cause of SZ

Question 6

Evaluation of neural correlates/dopamine explanation
- LIMITATIONS

Answer 6

P) evidence against DH from effectiveness of newer atypical antipsychotics drugs
E) only temporarily block dopamine receptors whilst also acting on serotonin receptors (block dopamine less well) but, more effective than the typical antipsychotics (that only act on dopamine receptors) in reducing SZ symptoms
E) dopamine clearly plays a role in SZ but there are other factors (eg other NTs like serotonin) which contribute
L) limited exp

P) neural correlates: cause and effect is unclear
E) brain abnormalities could be the effect rather than the cause of SZ
E) symptoms may cause changes in brain function rather than the other way round
L) we do not fully understand the role of neural correlates in the development of SZ
E) most studies are retrospective so hard to develop before/after image

P) biological explanations = determinist
E) suggest SZ is caused by factors (neural correlates or genes) outside of sufferers conscious control
(can be viewed both positively and negatively)
E) + more humane because it removes blame from the patient for developing SZ
E) - if an individual feels they have no control over developing the disorder they could engage in risk behaviours eg (substance abuse) which could trigger the onset

P) biological explanations = reductionist
E) focus wholly on internal factors (e.g. genes and neurochemistry) and ignore environmental factors
E) there are psychological explanations of SZ such as family explanations which argue that the way parents treat their child is the main influence SZ onset.
L) limited: biology alone may not explain all aspects of SZ