Lesson 2 - Biological Explanations of Schizophrenia

Question 1

What are the two factors that the biological explanations are based upon:

Answer 1

Genetic basis and neural correlates including the dopamine hypothesis

Question 2

What is the genetic basis?

Answer 2

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

Question 3

What are candidate genes?

Answer 3

There are specific genes that are associated with SZ, but now it is agreed that SZ is polygenic. Ripke et al (2014) found that there were 108 separate generic variations were associated with an increased risk of SZ. The genes that were particularly vulnerable were the ones that had some connection to the functioning of certain neurotransmitters such as dopamine

Question 4

Evaluation of genetic basis of Schizophrenia - Research Support

Answer 4

Gottesman, Joseph and Tienari’s study shows that there is a link between genes and SZ. This shows that if a child grows up in a family where both their biological parents has Schizophrenia.

Question 5

Evaluation of genetic basis of SZ - Ignores Nurture

Answer 5

Monozygotic twins are normally raised together, and sent to the same school, and wear the same clothes in childhood. This makes it difficult to separate upbringing from genes. Due to adoption also usually being by family members, they raise children similar to the birth parents, so even adoption studies may not work.

Question 6

Evaluation of genetic basis of SZ - Mutation of Genes

Answer 6

Schizophrenia can still occur in the absence of a family history of SZ. There may be a mutation in parental DNA which may be caused by radiation, poison or infection. Brown (2002) found that the older a father was during fertilisation, the more likely the child was to get to get schizophrenia. This suggests that nature and nurture are involved.

Question 7

Evaluation of genetic basis of SZ - Genetic vulnerability still requires a trigger

Answer 7

The diathesis stress model states that there is a genetic vulnerability to schizophrenia. People are born with this gene require a stress event in order to trigger the disorder. Clearly, this shows that biology alone cannot cause SZ, especially if the person lives a relatively stress free life.

Question 8

What are Neural correlates?

Answer 8

Neural correlates are measurements of the structure or function of the brain, and they have a relationship with SZ in different regions of the brain. Neural correlates also refers to how different neurotransmitters play a part in SZ.

Question 9

Evaluation of neural correlates (Different brain regions), Strength - Research Support

Answer 9

Torrey’s study showed enlarged brain ventricles, and Conrad’s study showed the same with the hippocampus. This shows that the brain does change in a Schizophrenic patient.

Question 10

Evaluation of neural correlates (Different Brain Regions), Strength - Brain Scans

Answer 10

The research evidence can be validated through brain scanning, which is an objective method. This gives neural correlates face validity, and this can help observe the structural brain changes that occur with schizophrenic patients.

This can help with the treatment of SZ in the future.

Question 11

Evaluation of neural correlates (Different Brain Regions), Weakness - Differences in patients

Answer 11

The problem with looking at different brain regions, is the fact that individuals actually suffer differently from SZ, and not all patients have deficits in the functioning of different brain regions.

Question 12

Evaluation of neural correlates (Different Brain Regions), Weakness - Hard to establish causation

Answer 12

Different brain regions are involved in SZ.

Due to this variation, it is actually difficult to pinpoint which brain region is causing the SZ symptoms.

Question 13

What is the dopamine hypothesis?

Answer 13

The dopamine hypothesis is the claim that an excess of the neurotransmitter dopamine, in certain regions of the brain, is associated with the positive symptoms of SZ. Thus messages from neurons that transmit dopamine fire too easily, and significantly too often, which leads to hallucinations and delusions. Schizophrenics are thought to have particularly high levels of D2 receptors on receiving neurons, which results in more dopamine binding, and more neurons firing.

Question 14

What is Hyperdopaminergia in the subcortex?

Answer 14

This is the idea that there are high levels of activity of dopamine in an area of the brain known as the subcortex (the central areas of the brain). For example, an excess of dopamine receptors in the Broca’s area (the area responsible for speech), may be associated with problems in speech and/or the experience of auditory hallucinations.

Question 15

What is Hypodopaminergia in the cortex?

Answer 15

The other theory is that there may be lower levels of dopamine in the cortex. Goldman-Rakic et al (2004) focused on the role of low levels of dopamine in the prefrontal cortex (responsible for decision making and thinking) on the negative symptoms of SZ.

Question 16

Evaluation of Neural Correlates (Dopamine Hypothesis) - Drug support for Hyperdopaminergia

Answer 16

This theory is supported through drug research, because dopamine antagonists such as amphetamines tend to increase dopamine levels, and this makes the schizophrenic symptoms worse in sufferers, and can even produce SZ-like symptoms in non-sufferers thus supporting the idea of Hyperdopaminergia.

Question 17

Evaluation of Neural Correlates (Dopamine Hypothesis) - Drug support for Hypodopaminergia

Answer 17

Antipsychotic drugs can reduce the levels of dopamine in schizophrenic patients, which helps control the symptoms of SZ. This supports the hypodopaminergia idea as lowered dopamine levels results in less symptoms. This was found by Tauscher et al (2014).

Question 18

Evaluation of neural correlates (Dopamine Hypothesis - Schizophrenics produce dopamine faster

Answer 18

Lindstroem et al (1999) found that the chemicals required to produce dopamine are actually consumed faster in the brains of schizophrenics when compared to controls, which suggests that schizophrenics do indeed produce more dopamine.

Question 19

Evaluation of neural correlates (Dopamine Hypothesis) - Does not acknowledge other factors

Answer 19

One main issue with the dopamine hypothesis is that it cannot be the sole cause of SZ. There are other biological and psychological factors that contribute such as upbringing or cognitive explanations, which focuses on impaired thinking. It also does not acknowledge.

Question 20

Evaluation of neural correlates (Dopamine hypothesis) - Cause and effect issues

Answer 20

It is hard to say whether high or low levels of dopamine cause SZ. There is definitely a connection between high dopamine and positive SZ symptoms, but it is hard to say whether the individual had excess levels of dopamine in that brain region, or did the symptoms come first.