A01

• What are 2 biological explanations for schizophrenia?

  Genetic factors and neural correlates
• What are genetic factors?

  Inherited factors make certain individuals more likely to develop a behaviour or mental disorder
• What evidence shows supports for genetic influences?

  - Gottesman (1991) - higher concordance rates between first-degree relatives

  - Children with 2 schizophrenic parents = 46% concordance rates

  - Children with 1 schizophrenic parent = 13%

  - Siblings = 9%
• What are neural correlates?

  Changes in neuronal events and mechanisms that result in the characteristic symptoms of a behaviour or mental disorder
• What is the dopamine hypothesis?

  Claims that an excess of the neurotransmitter dopamine in certain regions of the brain is associated with the positive symptoms of schizophrenia and lack of dopamine with negative symptoms
• What is hyperdopaminergia?

  Excessive levels of dopamine in the subcortex and Broca's area
• What is hypodopaminergia?

  Low levels of dopamine in the prefrontal cortex
• What are two other changes in the brain linked to symptoms of schizophrenia?

  1. Reduced activity in the ventral striatum (reward system) - linked to avolition

  2. Enlarged ventricles - linked to negative symptoms
• What evidence has shown the role of neural correlates in the development of schizophrenia?

  Juckel et al. (2006) - found lower levels of activity in ventral striatum in patients compared to controls
• What evidence has shown the role of the dopamine hypothesis in the development of schizophrenia?

  Successful drug treatments which change levels of dopamine activity - antipsychotic drugs (reduce dopaminergic activity) eliminate positive symptoms of schizophrenia
• What is a study which shows support for the influence of genetic factors?

  • Stephen Ripke et al. (2014)
  • Studied the genetic makeup of 37,000 patients and found:
  • 108 separate variations associated with increased risk of schizophrenia
  • The genes found were those that code for the functioning of neurotransmitters, including dopamine
• What does the original version of the dopamine hypothesis state?

  Original version of the hypothesis stated that excessive levels of dopamine are found in the subcortex and Broca’s area of schizophrenics leading to the positive symptoms (e.g. hallucinations)
• What does the latest version of the dopamine hypothesis state?

  Low levels of dopamine in the prefrontal cortex of schizophrenics’ brains leading to negative symptoms
• What study supports the impact of enlarged ventricles on the development of schizophrenia?

  • Torrey (2002)
  • The ventricles of a person with schizophrenia are on average about 15% bigger than normal