Schizophrenia - Biological explanations

• ‘Most modern mental health professionals believe schizophrenia is at least partly biological in origin’ True/False


  True
• What are the 3 explanations involved in biological origin of schizophrenia?

  • Genetic basis
  • Neurotransmitter dopamine
  • Neural correlates
• What is the genetic basis for schizophrenia?

  Greater genetic similarity between family members is associated with likelihood of both developing it
• Who’s graph shows a strong relationship between genetic similarity and shared risk of schizophrenia?

  Gottesman
• What does genetic explanation suggest?

  Schizophrenia is inherited through generations through the transmission of genes
• What 3 types of research do biological psychologists use to investigate the impact of genes?

  • Family studies
  • Twin studies
  • Adoption studies
• What did Gottesman find in his family study for genetic explanations of schizophrenia?

  Found children with 2 schizophrenic parents had a concordance rate of 46% whereas children with 1 schizophrenic parent had 13%
• According to Gottesman’s graph what % did identical twins have for developing schizophrenia which suggests that as genetic similarity increases the probability of sharing schizophrenia also does?

  48%
• In siblings what is the concordance rate on Gottesman’s graph?

  9%
• What is the concordance rate for fraternal twins on Gottesman’s graph?

  17%
• What can explain the difference in concordance rates between siblings and fraternal twins even though they share 50% of the same genes?

  Nurture - the environment can have an impact on schizophrenia
• What are candidate genes?

  Gene thought to be associated with schizophrenia
• How is schizophrenia polygenic?


  It requires a number of factors to work in combination

  A collection of gene locations are associated with higher risk of developing schizophrenia
• What else is schizophrenia other than polygenic?

  Aetiologically heterogenous (different combinations of factors can lead to the condition)
• How was Ripke’s study laid out?

  Combined all previous data from genome-wide studies of schizophrenia
• Outline Ripke’s study into candidate genes

  • Genetic makeup of 37,000 patients compared to that of 113,000 controls
  • 108 separate genetic variations associated with increased risk of schizophrenia
  • Genes associated with increased risk included those coding for the functioning of a number of neurotransmitters such as dopamine
• What are neural correlates?

  Variations in neural structure and bio chemistry that are correlated with increased risk of developing schizophrenia
• What is the dopamine hypothesis?

  Suggests symptoms of schizophrenia are associated with imbalance of the dopamine neuro-transmitter across the brain
• What is hyperdopaminergia and what‘s it associated with?

  • Excessive amounts of dopamine in sub cortex can damage Brocas area and lead to auditory hallucinations
• What is hypodopaminergia and what’s it associated with?

  • Lower levels of dopamine in prefrontal cortex can lead to negative symptoms like avolition/speech poverty
• How did the dopamine hypothesis come about from observations?

  • Observed that dopamine releasing drugs can produce schizophrenic like symptoms in healthy patients
  • Anti-psychotic drugs reduce dopamine levels and decrease symptoms of schizophrenia
• What is dopamine?

  • Neurotransmitter that has an excitatory effect and is linked to sensation of pleasure
  • Unusually high levels associated with schizophrenia
  • Unusually low levels associated with Parkinson’s disease
• What is another neural correlate other than the neurotransmitter dopamine?

  Ventricles
• What are ventricles?

  Voids filled with cerebrospinal fluid deep within brain (thought to provide a cushioning effect for brain)
• What type of ventricles are associated with schizophrenia?

  Enlarged ventricles
• What are the evaluation points for biological explanations of schizophrenia?

  • Determinist and not holistic
  • Weakness of Gottesman’s study into genetic similarity and likelihood of developing schizophrenia (siblings and non-fraternal twins)
  • Evidence for dopamine (Curran) & (Tauscher)
• What is the limitation of biological explanations being determinist and reductionist?

  • Makes sufferers feel disempowered and schizophrenia inevitable. Other approaches are more comprehensive. Holistic explanation of schizophrenia would consider diathesis-stress approach where the root cause of the disorder is biological but an environmental stressor triggers the disorder
• What is the strength of evidence for dopamine?

  • Amphetamines increase dopamine and worsen symptoms in schizophrenic people
  • Induces symptoms in people without schizophrenia
  • (Tauscher) Antipsychotic drugs reduce dopamine activity and the intensity of symptom
• What is the weakness of Gottesman’s study into family studies investigating likelihood of schizophrenia?

  • Non fraternal twins and siblings share around 50% of the same genes but concordance rates were 17% for the former and 9% for the latter
  • Suggests environmental factors interact with biological factors as non fraternal twins are more likely to share the same environment