Biological Explanations

• comorbid

  2+ illnesses occur in same person
• Comorbidity in Schizophrenia: Study Support

  Buckley:

  
  

  50% of patients had depression and schizophrenia

  47% had addiction and schizophrenia

  23% had OCD and schizophrenia
• Symptom Overlap: Study Support

  Ellason And Ross:

  looked at  Symptoms of schizophrenia patients with those of dissociative identity disorder patients.

  RESULTS-

  Patients with dissociative identity disorder displayed more schizophrenic symptoms than patients with schizophrenia.
• Genetic Explanations of Schizophrenia

  There are multiple gene alleles that increase the risk of developing schizophrenia.

  If members of our family have schizophrenia, we are more likely to develop schizophrenia

  The fewer protective gene alleles a person has, the more likely they are to develop schizophrenia.
• The Genetic Explanation of Schizophrenia: Twin Studies

  Gottesman and shield:

  • conducted twin study that looked at concordance rate between MZ and DZ twins for schizophrenia
  • MZ= 74%
  • DZ = 24%
• The Genetic Explanation of Schizophrenia: Adoption Studies

  Tierni et al

  • two groups: experimental, control group
  • experimental: adopted children whose biological mothers were schizophrenic
  • control: adopted children whose mothers were not
  • children of schizophrenic mothers more likely to develop schizophrenia
• The Neural Correlates Hypothesis

  research shows that people with schizophrenia have abnormal brain structure such as...

  A) Larger ventricles

  B) smaller frontal cortex

  
• Torrey (2002)- neural correlates explanation on Schizophrenia

  MRI brain scan on schizophrenic people vs normal people

  15% had bigger ventricles if schizophrenic
• effects of medication on brain structure:

  • We don’t have sufficient evidence to conclude that brain abnormalities cause schizophrenia, because the evidence obtained from MRI studies are correlational.
  • The drug medication that patients take to treat schizophrenia may act as a confounding variable in studies of neural correlates.
• how do antipsychotics work?

  • prevent dopamine from binding to post-synaptic receptors
  • reduce overactivity of neuron's in mesolimbic pathway
• effects of antipsychotics

  • cause extra-pyramidal side effects (blocks motor cortex)

  e.g. stiff, jerky movements

  • obesity, heart problems, diabetes
• dopamine hypothesis

  • higher levels of dopamine in mesolimbic system = positive symptoms
• Noll- dopamine hypothesis (Limitation)

  • review previously conducted drug studies
  • His study suggested that dopamine not only cause for positive symptoms
• limitation to drugs that reduce dopamine

  
  

  • Montrcrieff: criticised dopamine hypothesis by finding that amphetamine also increases noradrenaline and serotonin along with dopamine
  • drugs that increase dopamine e.g. amphetamines also increase levels of other neurotransmitters, can't be sure that it is an increased dopamine that is causing these symptoms
• limitation to antipsychotic drugs

  • unable to treat negative symptoms
  • because:
  • antipsychotics affect dopamine in all areas of brain (including frontal cortex)
  • frontal cortex = dopamine already low
  • low dopamine levels = negative symptoms
• Typical + Atypical Antipsychotics

  Typical Antipsychotics: bind to receptors for long period of time to block dopamine

  Atypical Antipsychotics: newer antipsychotic drugs, bind to dopamine receptors for shorter periods of time

  • less side effects
  • might treat negative symptoms
• Support for Atypical Antipsychotics

  Leucht:

  Meta-analysis

  65 studies into effectiveness of antipsychotic drugs

  FINDINGS-

  Leucht found that antipsychotic drugs were more effective at treating schizophrenia than a placebo.

  antipsychotic drugs led to lower relapse rates.
• Comparing Effects of Atypical Antipsychotics and Typical Antipsychotics


  Crossley found that there was no significant difference between typical and atypical antipsychotics in how effective they were at preventing symptoms.

  Crossley could conclude that typical antipsychotics are a better treatment for people with schizophrenia, compared to atypical antipsychotics.
•  limitation of both typical and atypical antipsychotics?

  Patients who stop taking either drug are likely to experience relapse.

  (may not be treating underlying cause of disorder- just blocking symptoms)