Schizophrenia - biological explanations

• What does the genetic explanation of schizophrenia argue?

  Schizophrenia is inherited
• What did Gottesman study to determine the concordance rates of schizophrenia?

  Family studies of different relatives
• What is the concordance rate for MZ twins according to Gottesman's findings?

  48%
• What is the concordance rate for DZ twins?

  9%
• What is the concordance rate for cousins?

  2%
• What does the positive correlation in Gottesman's study suggest?

  More shared genes increases schizophrenia risk
• Which candidate genes are linked to schizophrenia?

  COMT and C4
• Why is schizophrenia considered polygenic?

  It involves multiple genes influencing development
• What evidence supports the genetic explanation of schizophrenia?

  • Rosenthal's case study on Genain quadruplets
  • Quadruplets shared 100% of genes
  • All developed schizophrenia in early 20s
  • Family history of schizophrenia present
• What limitation exists regarding concordance rates for MZ twins?

  They are never 100% despite genetic similarity
• What does the limitation of MZ twin concordance rates suggest?

  The theory may be reductionist and incomplete
• What does the original dopamine hypothesis suggest?

  High dopamine levels cause positive symptoms
• What are the positive symptoms of schizophrenia?

  Hallucinations and delusions
• What does the revised dopamine hypothesis by Davis et al suggest?

  Low dopamine in cortex leads to negative symptoms
• How do high and low dopamine levels relate to schizophrenia symptoms?

  They can occur simultaneously with both symptoms
• What evidence supports the original dopamine hypothesis?

  • Iverson's post mortem studies (1979)
  • Compared 50 schizophrenia patients to controls
  • Found higher dopamine in limbic areas
  • Supports link between dopamine and schizophrenia
• What limitation exists regarding neural explanations of schizophrenia?

  Cause and effect is difficult to determine
• Why is it unclear whether dopamine levels cause schizophrenia?

  Medication may alter dopamine levels post-diagnosis
• What structural brain change is associated with schizophrenia?

  Lateral ventricular enlargement
• What evidence supports the link between schizophrenia and lateral ventricles?

  • Torrey and Weinberger's study (1979)
  • Compared twins with and without schizophrenia
  • Found enlarged lateral ventricles in affected twin
  • Suggests a brain structure link to schizophrenia
• What limitation exists regarding the explanation of enlarged lateral ventricles?

  Cause and effect is difficult to determine
• Why is it problematic if cause and effect cannot be established?

  It questions the validity of the theories