Biological explanations for schizophrenia

Question 1

Genetics

Answer 1

Schizophrenia could be inherited from the shared genes of relatives that also have the disorder. Gottsman (1991) found that if one identical twin had schizophrenia then there is almost a 50% chance that the other twin will have the disorder as well.

Question 2

Polygenic

Answer 2

as there are several genes that are linked to the disorder. These candidate genes include those that affect the functioning of dopamine.

Question 3

Aetiologically heterogeneous

Answer 3

that different combinations of genes can lead to the disorder. E.G. Ripke et al (2014) studied the genetic makeup of 37,000 patients and identified 108 separate genetic variations.

Question 4

The dopamine hypothesis

Answer 4

suggests that schizophrenia is caused by high or low levels of the neurotransmitter dopamine.
D2 receptors influence attention and perceptions therefore if neutrons fire too often then you are more likely to experience distortions in perception like hallucinations
Low levels in the pre frontal cortex links to disordered thinking

Question 5

Neural correlates

Answer 5

Juckel et al (2006) found lower levels of activity in the ventral striatum. (links to rewards and could explain low motivation)
Allen et al (2007) found lower activity in the anterior cingulate gyrus who suffered auditory hallucinations. (links to imagination therefore could explain these hallucinations)

Question 6

Evaluation strength: Tienari et al (1994)

Answer 6

found that adopted children who had a schizophrenic parent had a 10% chance of developing schizophrenia in comparison to other adopted children who did not.

Question 7

Evaluation strength: Brown et al (2002)

Answer 7

found a positive correlation between parental age and risk of schizophrenia, increasing from 0.7% with fathers under 25 to over 2% in fathers over 50. (mutated sperm)

Question 8

Evaluation weakness: Concordance rates amongst MZ twins are not 100%

Answer 8

suggests that environmental factors also play a role in the disorder as MZ twins are genetically the same so if genes determine everything, they should have exactly the same behaviour when this isn’t the case.

Question 9

Evaluation weakness: The dopamine hypothesis is oversimplified

Answer 9

The anti-psychotic drug clozapine is the most effective drug at reducing symptoms despite it acting on serotonin as well as dopamine.

Question 10

Evaluation weakness: Causation issues

Answer 10

perhaps the patient gets schizophrenia first which then leads to changes in the neurotransmitter levels in areas like the prefrontal cortex. (there may be other factors)