Biological explanation

• Genetic explanation:

  • suggests schizophrenia is inherited and results from the activity of certain genes
  • schizophrenia is polygenic —> collection of genes associated with higher risk
• Ripke et al - 2014

  • genetic analysis of 36,000 schizophrenia cases
  • identified 108 genetic locus associated with the development of the disorder
  • polygenic
  • aetiologically heterozygous - different combinations of genes are correlated with having the disorder
• concordance rate - the more closely related 2 people are, the more likely that if one person has schizophrenia so will the other
• Gottesman - 1991

  • studied schizophrenia in families

  found concordance rate of:

  • 48% in monozygotic twins
  • 17% in dizygotic twins
  • suggests there is a genetic aspect as large difference between MZ and DZ
  • both are much higher than general population (1%)
  • both share similar environments
  • not 100% concordance rate so not fully genetic
• Tienari - 2004

  • studied adopted children of biological schizophrenic mother
  • 5.8% of children adopted into psychologically healthy families developed schizophrenia
  • 36.8% of children raised in dysfunctional families developed schizophrenia
  • suggests genetic basis as both much higher than 1%
  • suggests psychological factors play a role
• what are neural correlates?


  variations in neural structure and biochemistry that are correlated with higher risk of developing schizophrenia

  e.g dopamine hypothesis
• what is the dopamine hypothesis?


  symptoms are associated with too much or an imbalance of dopamine across the brain

  exact mechanism not know - it is though that:

  • excessive amounts of dopamine in the brain in speech centres may lead to auditory hallucinations (hyperdopaminergia)
  • lower levels of dopamine in frontal area leads to negative symptoms like avolition and speech poverty (hypodopaminergia)

  evidence:

  • observations that dopamine releasing drugs can produce schizophrenia like symptoms in healthy patients
  • antipsychotic drigs that decrease schizophrenia symptoms reduce dopamine levels
• What is glutamate?


  excitatory neurotransmitter

  • involved in learning, attention and memory
  • found in low quantities in people with schizophrenia
• what is another effective treatment?

  serotonin
• AO3 of dopamine hypothesis?

  Leueht et al:

  • meta-analysis of 212 studies
  • assessed effectiveness of biological antipsychotic drugs that worked by normalising levels of dopamine
  • drugs were more effective than placebo
  • suggests the theory has validity
• What are ventricles?


  voids filled with cerebrospinal fluid deep in the brain

  • thought to provide protective cushioning
  • found enlarged ventricles are associated with people with schizophrenia
• ventricles A03?


  Johnstone - 1976

  • identified this using CT scans
  • structural difference may be linked to schizophrenia

  counterpoint:

  • may be due to third factor e.g medication as it is based off correlational research
• determinist vs free will?


  biological approach assumes schizophrenia is inevitable and biologically determined

  • can make sufferers feel disempowered
• reductionist vs holistic?


  reductionist:

  • explained at basic cellular and chemical level
  • fewer assumptions
  • biological reductionism fails to consider evidence for range of psychological aspects e.g expressed emotion

  holistic:

  • would consider diathesis stress model
  • root cause of disorder is biological/genetic weakness
  • environmental stressor e.g family stress triggers disorder