Biological Schiz

• Biological explanations


  Explanations for schizophrenia based on genetics and neural correlates
• Genetic explanation


  Schizophrenia is inherited or caused by specific genes
• Inheritance


  Schizophrenia runs in families, closer genetic relationship increases risk
• Family studies


  Schizophrenia risk is higher in first-degree relatives
• Twin studies


  Higher concordance rate in monozygotic twins compared to dizygotic twins
• Adoption studies


  Children with schizophrenic biological mothers have higher risk
• Specific genes


  Schizophrenia is polygenic and caused by multiple genes
• PPP3CC gene


  Defective version of a gene associated with schizophrenia
• Chromosome 5 gene


  Gene linked to schizophrenia in some families
• Evaluation of genetic explanations

  Genes alone cannot fully explain schizophrenia, other factors involved
• Nature vs. nurture


  Difficulty separating genetic and environmental influences
• Mutation in parental DNA


  Mutation in paternal sperm cells increases risk of schizophrenia
• Location of specific genes

  No definitive results, underlying mechanism unclear
• Dopamine hypothesis


  Schizophrenia caused by excessive activity of dopamine
• Dopamine


  Neurotransmitter responsible for transmitting signals between neurons
• Dopamine receptors


  High density and sensitivity associated with schizophrenia
• Positive symptoms


  Associated with high levels of dopamine in mesolimbic system
• Negative symptoms


  Associated with high levels of dopamine in mesocortical system
• Clozapine


  New drug effective against schizophrenia, affects dopamine and other neurotransmitters
• Evaluation of dopamine hypothesis

  Simplistic, other neurotransmitters involved, practical applications
• Dopamine abnormalities


  More dopamine receptors in schizophrenics, evidence of abnormalities
• Neural correlates


  Schizophrenia caused by structural and functional brain abnormalities
• Enlarged ventricles


  Fluid-filled gaps between brain areas associated with schizophrenia
• Negative symptoms


  Enlarged ventricles associated with negative symptoms
• Research methods


  Post-mortems and non-invasive scanning techniques used
• Loss of brain tissue


  Enlarged ventricles suggest a loss of brain tissue in schizophrenia
• Evaluation of neural correlates

  Enlarged ventricles only explain certain symptoms, inconclusive evidence
• Effect vs. cause


  Enlarged ventricles may be a consequence rather than the cause of schizophrenia
• Structural brain damage


  Brain damage evident at first onset, worsens over time