Biological explanations

• What does heritability refer to in the context of schizophrenia?

  Heritability refers to the extent to which a condition or trait has been passed on generationally through families via genes.
• What was the concordance rate for schizophrenia found by Gottesman (1991) between MZ twins?

  48%
• What does Gottesman’s (1991) findings imply about genetic links and schizophrenia?

  The closer the genetic link between you and someone with schizophrenia, the higher the chance you have of also developing the illness.

  
• Is there a single gene identified as causing schizophrenia?

  No, it is thought that schizophrenia involves the combined effect of several genes.
• What are the genes that may increase a person’s risk of developing schizophrenia called?

  Candidate genes.

  
• Why is schizophrenia referred to as polygenic?

  Because it involves several candidate genes that contribute to the risk of developing the condition.

  
• What are some candidate genes implicated in schizophrenia according to Salleh (2004)?

  Neuregulin 1, dysbindin, and proline dehydrogenase.
• What role do the candidate genes mentioned play in schizophrenia?

  They are implicated in the production and regulation of key mood-related neurotransmitters.
• How has the Human Genome Project contributed to understanding schizophrenia?

  It has helped researchers identify key candidate genes that may code for schizophrenia.
• What is the main finding of McCarroll et al. (2016) regarding genetic risk for schizophrenia?

  The strongest known genetic risk for schizophrenia comes from the gene known as C4.

  
• What did Haraldsson (2011) find in his meta-analysis regarding candidate genes?

  Some candidate genes in combination increase vulnerability to schizophrenia.
• What are the strengths of the genetic basis of schizophrenia?

  • Clinical and objective methods used for measurement
  • Not affected by individual differences, ensuring good reliability and validity
  • Compelling body of research evidence supports genetics' role in schizophrenia
• What are the weaknesses of the genetic basis of schizophrenia?

  • Concordance rates for MZ twins are not 100%, indicating other factors are involved
  • Symptoms of schizophrenia vary widely among individuals
  • Absence of a biomarker complicates definitive diagnosis
• What do neural correlates of schizophrenia refer to?

  Specific brain regions/structures/functions implicated in the symptoms and behaviors associated with the disorder.
• Which brain structure is associated with the negative symptoms of schizophrenia?

  The ventral striatum (VS).
• What is the relationship between the ventral striatum and apathy in schizophrenia?

  Schizophrenic patients show less activity in the VS, which is associated with apathy.
• Which brain structure is associated with the positive symptoms of schizophrenia?

  The superior temporal gyrus (STG).
• What is the link between reduced volume of grey matter in the STG and schizophrenia?

  It is associated with hallucinations and thought disorder.

  
• What is the dopamine hypothesis (DH) in relation to schizophrenia?

  It claims that overstimulation of dopamine receptors may contribute to vulnerability to schizophrenia.
• What does hyperdopaminergia refer to in the context of the dopamine hypothesis?

  It refers to an excess of dopamine activity in the sub-cortex, potentially causing positive symptoms.
• What is the role of the prefrontal cortex (PFC) in schizophrenia according to the newer version of the dopamine hypothesis?

  The PFC is thought to control executive functions, and low dopamine levels there are linked to negative symptoms.
• What does current understanding suggest about dopamine levels in schizophrenia?

  Both hyperdopaminergia and hypodopaminergia may be at work in different brain areas.
• What did Shenton et al. (1992) find regarding the left superior temporal gyrus?

  Reduced grey matter volume was found, which is related to thought disorder.
• What is the association between low levels of activity in the ventral striatum and schizophrenia?

  It may be associated with the negative symptom of avolition.
• How do antipsychotic drugs like clozapine and risperidone function in relation to dopamine?

  They act as dopamine antagonists, reducing hyperdopaminergia and associated symptoms.
• What did Davis et al. (1991) conclude about dopamine activity in schizophrenia?

  Schizophrenia is linked to abnormally low PFC dopamine activity, leading to excessive activity in the sub-cortex.
• What are the strengths of using brain-imaging techniques in schizophrenia research?

  • Provide objective evidence for neural correlates
  • Pinpoint specific brain structures implicated in symptoms
  • Conducted under controlled clinical conditions for reliability
• What are the weaknesses of neural correlates research in schizophrenia?

  • Correlational approach lacks cause-effect explanation
  • No acknowledgment of environmental factors
  • Lacks external validity
• How does a neural correlates explanation of schizophrenia relate to biological determinism?

  It assumes specific brain structures and dopaminergic activity play a key role in the onset of schizophrenia.
• What is the purpose of the worked example provided in the study material?

  To illustrate how to discuss the genetic explanation for schizophrenia and address concerns about having children.
• What should a high-scoring answer on neural correlates of schizophrenia include?

  A clear outline, effective use of examples, and confident use of terminology.
• What is the expected structure of a low-scoring answer on neural correlates of schizophrenia?

  It may lack detail, use sparse terminology, and have possible inaccuracies.