SZ- Biological Explanations

Question 1

What are biological explanations of schizophrenia based on?

Answer 1

They are based on three factors:

• Genetic basis
• Dopamine hypothesis
• Neural correlates

Question 2

What does the genetic explanation of schizophrenia suggest?

Answer 2

• The suggestion here is that schizophrenia runs in families by studying family members and the occurrence of schizophrenia.
• Schizophrenia is thought to be polygenic, with lots of different genes called candidate genes contributing to an increased risk of developing it.

Question 3

How are genetic factors normally tested?

Answer 3

Genetic factors are normally tested through family, twin and adoption studies.

Question 4

Give an example of a study into family members.

Answer 4

• One of the many twin studies is Gottesman’s study.
• He found a 48% concordance rate for MZ twins, and 17% rate for DZ twins.
• Therefore this study shows that the more genes an individual shares with the sufferer, the more likely they are to have the disorder, suggesting there may be a genetic basis for schizophrenia.

Question 5

Evaluate the genetic explanation. (Advantage)

Answer 5

1) There is a wealth of research evidence to support the genetic basis for SZ as can be seen from the findings of Gottesman’s and many other psychologists’ study.
- For example, Tienari et al (2004) found that adopted children of biological mothers with schizophrenia were more likely to develop the disorder themselves than adopted children of mothers without schizophrenia, supporting the genetic link

Question 6

Evaluate the genetic explanation (Disadvantage)

Answer 6

1) As identical twins share 100% of their genes, it would be expected that the concordance rate for schizophrenia would be 100% if it was purely genetic. As it is only around 50%, this suggests other influences are playing a part.
- For example, the diathesis stress model suggests that a person is more likely to get schizophrenia if they have the gene for the illness as well as a trigger in the environment.

Question 7

What does the dopamine hypothesis suggest?

Answer 7

Schizophrenia is caused by abnormal levels of the neurotransmitter dopamine.

Question 8

What is hyperdopaminergia?

Answer 8

• This refers to higher than usual levels of dopamine in the subcortex (central areas of the brain).
• This is linked with positive symptoms such as hallucinations.
• There may be a higher number of dopamine receptors, causing over-activity of dopamine, causing sensory hallucinations.

Question 9

What is hypodopaminergia?

Answer 9

• This refers to lower than usual levels of dopamine in the cortex (outer part of the brain), where less dopamine is being transmitted across synapses.
• This is linked with negative symptoms, as there is a reducing in normal functioning.

Question 10

Evaluate the dopamine hypothesis. (Advantage)

Answer 10

• Tauscher et al (2014) found that giving patients antipsychotic drugs which lower dopamine levels (antagonists- reducing activity) reduced the occurrence of positive symptoms, supporting the hyperdopaminergia aspect of the hypothesis.

Question 11

Evaluate the dopamine hypothesis. (Disadvantage)

Answer 11

• The dopamine hypothesis could be viewed as being reductionist. It looks at the complicated phenomenon of the causes of schizophrenia and reduces it down to the component of dopamine alone. There might be other factors or causes of schizophrenia that have been ignored e.g. neuroanatomy of the brain.
• Also, the cause and effect is unclear.
• Could it be that an increase in dopamine causes schizophrenia to develop; or could it be that the illness develops first (due to another cause) and then this causes dopamine levels to increase?

Question 12

What does the neural correlates hypothesis suggest?

Answer 12

There is growing evidence that schizophrenia is down to abnormalities in the brain. The structure or functioning of the brain is correlated (associated) with positive and negative symptoms.

Question 13

Which area of the brain is associated with negative symptoms?

Answer 13

• The ventral striatum is involved with reward anticipation.
• Schizophrenia patients have been found to have less activity in this region- the lower the activity, the more severe the negative symptoms.
• This could explain avolition (loss of motivation).

Question 14

Which area of the brain is associated with positive symptoms?

Answer 14

• Allen et al (2007) scanned the brains of patients experiencing hallucinations whilst they completed an auditory processing task.
• Lower activation levels were found in the superior temporal gyrus and anterior cingulate gyrus, and they made more errors, compared to a control group.
• Auditory hallucinations are therefore correlated with reduced activity in these areas.