Biological Explanations and Treatments

• Genetic Basis : Family and Adoption Studies

  Gottesman - concordance rates for schizophrenia in MZ twins are 48%, compared to 17% for DZ

  Tienari et al - of 164 adoptees with schizophrenic mothers, 11 also got a diagnosis. They are 3x more likely to receive the same diagnosis than a non-schizophrenic mother
• Candidate Genes


  Early research said there was one 'schizogene', but it now appears that there is a combination of genes that make people vulnerable, it is polygenic. It is also aetiologically heterogenous as there are different combinations, but most genes involve code for neurotransmitters:

  • Ripke et al - genome wide study and found 108 genetic variations associated with schizophrenia
• Role of Mutation


  Schizophrenia can have a genetic origin without a family history because of mutations in parental DNA casued by:

  • radiation
  • poison
  • viral infection
  • age

  Brown et al - positive correlation between parental age and risk of schizophrenia (2% in fathers over 50)
• Neural Basis


  Neural correlates = patterns of structure or activity in the brain that occurs in conjunction with an experience and may be implicated in the origins of that experience.
• Role of Dopamine


  = sensors motivation to motivate a response.

  The original dopamine hypothesis was based on the discovery that drugs used to treat schizophrenia caused symptoms that lowered dopamine levels.

  • Suggests schizophrenia is the result of high dopamine levels in the subcortex (hyperdopaminergia)
• Updated dopamine hypothesis


  Davis et al

  • Hyopdopaminergia (low dopamine) in the cortex is associated with schizophrenia
  • Explains symptoms and cognitive problems e.g. negative symptoms
• Neural correlates : Research

  Juckel et al

  • low levels of activity in ventral striatum in schizophrenia patients
  • leads to severe negative symptoms
• Eval : Strength - Genetics

  Gottesman's study demonstrates that genetic similarity and shared risk of schizophrenia are closely related. Provides good validity.
• Eval : Strength - Neural 


  Leucht et al carried out a meta-analysis of 212 studies and found that all drugs were more effective than placebos in changing dopamine levels. Shows dopamine plays a significant role.
• Eval : Weakness


  Both explanations suffer from biological reductionism as they both concentrate solely on biological factors. In Gottesman's study the rate for MZ twins wasn't 100% meaning there must be other factors involved.