Biological explanations

• What is the global prevalence of schizophrenia?

  About 1%
• What does the consistent prevalence of schizophrenia worldwide suggest?

  It supports a biological view of mental disorders.
• What are the assumptions of the biological approach to mental disorders?

  • All mental disorders have a physical cause.
  • Mental illnesses can be described in terms of clusters of symptoms.
  • Symptoms can be identified, leading to diagnosis.
  • Diagnosis leads to appropriate physical treatments.
• What is a key finding regarding the genetic explanation of schizophrenia?

  Schizophrenia appears to run in families.
• What did Gottesman's study in 1991 reveal about genetic risk for schizophrenia?


  The risk of developing schizophrenia is proportional to the amount of genes shared.
• What is the term used to describe the influence of multiple genes on schizophrenia?

  Polygenic
• What did Riphe et al. (2014) find in their study of 37,000 patients?


  They found 108 variations of genes associated with schizophrenia.
• What were the results of the twin studies conducted by Gottesman and Shields?


  • 54% concordance rate in monozygotic twins.
  • 18% concordance rate in dizygotic twins.
• Why can't twin studies provide a complete explanation for schizophrenia?

  They cannot rule out environmental factors affecting concordance rates.
• What did Kety (1984) find regarding offspring of mothers diagnosed with schizophrenia?


  Schizophrenia was diagnosed 5 times higher in the high-risk group.
• What did Tienari (2000) discover in his adoption studies?

  Schizophrenia was diagnosed 5 times higher in the high-risk group of adopted-away offspring.
• What are some problems with twin studies in schizophrenia research?

  • No study has found 100% concordance rate.
  • MZ twins may have more similar environments than DZ twins.
  • Cannot rule out environmental factors.
• What is the dopamine hypothesis in relation to schizophrenia?


  It suggests schizophrenia is caused by excessive dopamine activity.
• What are some neurotransmitters implicated in schizophrenia?


  Dopamine, serotonin, and glutamate.
• What brain abnormalities are associated with schizophrenia?

  Enlarged ventricles and abnormalities in the ventral striatum and superior temporal gyrus.
• What are the positive and negative symptoms of schizophrenia associated with neural correlates?

  Positive Symptoms:

  • Hallucinations: Superior temporal gyrus

  
  

  Negative Symptoms:

  • Avolition: Ventral striatum
• What did Seeman (1987) find in his meta-analysis regarding dopamine levels in schizophrenia patients?


  He found a 60-110% increase of dopamine in those with schizophrenia compared to controls.
• How do phenothiazines relate to schizophrenia treatment?


  They are anti-psychotic drugs that block dopamine at the synapse.
• What did Carron et al. (2004) find regarding L-DOPA and amphetamines?


  They can increase dopamine levels and worsen symptoms in people with schizophrenia.
• What did Andreasen et al. (1990) find in their CAT scan study of schizophrenia patients?


  They found significant enlargement of the ventricles in schizophrenia patients compared to controls.
• What is a limitation of Andreasen et al.'s study?


  It was gender-biased and not representative of the whole population.
• What did Allen et al. (2009) discover about brain activity in schizophrenia patients with auditory hallucinations?


  They found lower levels of activity in the superior temporal gyrus compared to controls.
• What did Jucket et al. (2006) find regarding brain activity in schizophrenia patients with avolition?

  They found lower levels of activity in the ventral striatum compared to controls.
• What are some limitations of the neural correlates explanation for schizophrenia?


  • Overly deterministic; not everyone with excess dopamine has schizophrenia.
  • Correlational research; cannot establish cause and effect.
  • Reductionistic; ignores other neurotransmitters like glutamate.