Biological explanation

• There is evidence that schizophrenia is inherited and is, in part, genetic. Gottesman indicates that the closerthe genetic relationship to someone with schizophrenia, the greater the chance of developing the disorder.

  • MZ twins have a concordance rate of 48% whereas DZ twins have a concordance of 17%
• What is a main limitation of concordance rates?

  They compare people in the same environment
• How can the environmental factor in schizophrenia be isolated?

  By studying adopted children's schizophrenia levels
• Who conducted a study on children of schizophrenic mothers?

  Heston
• What was the sample size of children studied by Heston?

  47 children of schizophrenic mothers
• What was the control group size in Heston's study?

  50 children raised in the same homes
• What percentage of children with schizophrenic biological mothers developed schizophrenia in Heston's study?

  17%
• What was the outcome for the control group in Heston's study regarding schizophrenia?

  None developed schizophrenia
• How does Heston's study contribute to understanding the role of genetics in schizophrenia?

  It shows a genetic link through biological mothers
• Appears a number of genes are involved in schizophrenia.

  Ripke et al

  • 37000 cases of schizophrenia and compared them with 113000 controls
  • found 108 separate genetic variations assosciated with slightly increased risk of it
  • there isnt a single faulty gene that can explain it which means that it is polygenic
  • the most likely would be the ones that code for neurotransmitters such as dopamine
• Genetics are unlikely to be the sole factor since the concordance rates for MZ twins show otherwise

  As the concordance rates are not 100%, this shows that there may be a pre dispositional explanation, which makes them more at risk. By focusing on one factor, it can suggest a reductionist approach as other factors are not considered, such as family dynamic or biochemistry.
• Neural correlates

  • The dopamine hypothesis
  • High levels of dopamine is known as hyperdopaminergia, where as low levels is known as hypodopaminergia.
  • In the original dopamine hypothesis, high levels of dopamine in the subcortical areas of the brain, e.g. excess dopamine receptors from the subcortex pathways to Broca's area, result in speech poverty or auditory hallucinations
  • Based on the idea that drugs used to treat schizophrenia can lead to symptoms of Parkinson's, which is linked to the neurotransmitter, dopamine.
  • Updated hypothesis- low dopamine in the cortex is linked to negative symptoms.
• A weakness of the hypothesis is that newer drugs such as clozapine, are more effective than traditional ones. These new drugs affect dopamine as well as other neurotransmitters, such as serotonin.

  • Appears that several neurotransmitters may be involved in the development of schizophrenia, and therefore the hypothesis is too simplistic. Along with dopamine and serotonin, the research implicates glutamate.
  • Evidence for raised levels of this in several brain regions.
• A strength is that it has practical applications and has led to the development of treatment. New drugs have been developed and can be more effective than neuroleptics at relieving schizophrenic behaviour.

  • suggests that psychiatrists can understand the role played by neurotransmitters when treating different types of schizophrenia and thus improve quality of life.
• Biological explanations

  • criticised for being biologically reductionist.
  • oversimplifies in terms of genes and neurotransmitters, the social context within which it develops has not been considered.
  • in order to explain schizophrenia effectively, it would be better to take an interactionist approach, such as the diathesis stress model.
  • suggests that biological factors pre dispose someone to schizophrenia, but this has to be 'triggered' by some sort of experience.