Biological Explanations for Schizophrenia

• 2 biological explanations for schizophrenia

  1. genetic factors
  2. neural correlates- the dopamine hypothesis, reduced activity in ventral striatum and enlarged ventricles
• genetic factors

  inherited factors make certain individuals more likely to develop a behaviour or mental disorder
• neural correlates

  changes in neuronal events and mechanisms that result in the characteristic symptoms of a behaviour or mental disorder
• 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
• hyperdopaminergia

  excessive levels of dopamine in the subcortex and Broca's area
• hypodopaminergia

  low levels of dopamine in the prefrontal cortex
• 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
• genetic factors: Gottesman

  the more genetically similar you are to a family member the higher the shared risk of schizophrenia

  • general population= 1%, parents= 6%, children= 13%, identical twins= 48%
• reduced activity in the ventral striatum

  • this region is crucial in anticipation of reward
  • schizophrenia= lower levels of activity here= avolition
• enlarged ventricles

  • ventricles supply nutrients and remove waste
  • brains of schizophrenics are lighter than normal
  • ventricles= 15% larger (Torrey 2002)

  linked with negative symptoms