biological explanations for schizophrenia

• genetic factors: twin studies, adoption studies, family studies
• twin studies: monozygotic twins have a higher likelihood of both having schizophrenia, in comparison to dizygotic twins
• adoption studies: Adopted children who live with their biological parents are more likely to have schizophrenia. In comparison to adopted children living with their adoptive parents, their schizophrenia will correlate with their biological parents who might’ve had a history of schizophrenia. There is evidence for a strong biological basis, although it is limited because its a holistic view where there is evidence that environmental factors could also affect if you do or don’t have schizophrenia
• family studies: schizophrenia is more common among biological relatives of the person w/ schizophrenia, so if someone in your family has a history of schizophrenia, you are a lot more likely to also develop schizophrenia
• serotonin is mood
• dopamine is pleasure
• excess of dopamine develops positive symptoms for schizophrenia
• loss of dopamine develops negative symptoms of schizophrenia (revised dopamine hypothesis)
• neural correlates: the dopamine hypothesis + revised dopamine hypothesis
• dopamine hypothesis: claims that an excess of the neurotransmitter dopamine in certain regions of the brain is associated w/ the positive symptoms of schizophrenia, they are thought to have abnormally high numbers of D receptors on receiving neurons
• specific brain areas involved in schizophrenia: prefrontal cortex, hippocampus, grey matter + white matter
• prefrontal cortex:

  • Main area of the brain involved in executive control (e.g. planning, reasoning + judgement)
  • Research has shown that this is impaired in schizophrenia patients 
  • It has been hypothesised that the cognitive symptoms of schizophrenia result from deficits within the prefrontal cortex + its connections w/ other areas of the brain, particularly the hippocampus 
• hippocampus :

  • Area of the brain is the temporal lobe 
  • Several studies have reported anatomical changes in the hippocampus in schizophrenia patients 
  • Deficits in the nerve connection between the hippocampus + the prefrontal cortex have been found to correlate w/ the degree of working memory impairments = a central cognitive impairment in schizophrenia 
  • Goto and Grace suggest that hippocampal dysfunction might also influence levels of dopamine release in the basal ganglia indirectly affecting the processing of information in the prefrontal cortex 
• What is the effect of schizophrenia on grey matter volume?

  It reduces grey matter volume in the brain
• In which lobes is grey matter volume particularly reduced in people with schizophrenia?

  Temporal and frontal lobes
• What have researchers found about the ventricles in people with schizophrenia?

  They often have enlarged ventricles
• What is thought to cause enlarged ventricles in schizophrenia?

  Nearby brain parts not developing properly
• What did Cannon et al. find regarding grey matter loss in high clinical risk individuals?

  They showed a steeper rate of grey matter loss
• How does the rate of brain ventricle expansion compare in those who develop schizophrenia versus those who do not?

  Greater rate of expansion in those who develop it
• What is the relationship between grey matter loss and the development of schizophrenia according to Cannon et al.?

  Steeper grey matter loss correlates with developing schizophrenia
• What symptoms are particularly noted in people with schizophrenia who have enlarged ventricles?

  Negative symptoms
• What is the significance of the findings by Cannon et al. regarding clinical risk?

  It indicates a link between risk and brain changes
• What is white matter primarily composed of?

  Fatty bits of the neuron
• How can white matter be compared to meat?

  It is similar to the fatty part of meat
• Where is white matter found in the body?

  In the brain and spinal cord
• What is the role of myelin in white matter?

  It creates an insulating sheath around nerve fibers
• How does myelin affect information conduction?

  It helps conduct information quickly
• What does efficient information processing in the CNS depend on?

  Myelin's insulating properties
• What has research found about myelination in schizophrenic patients?

  Reduced myelination of white matter pathways
• Which neural pathways are particularly affected in schizophrenia?

  Between the prefrontal cortex and hippocampus
• What is the significance of myelination in the context of schizophrenia?

  It is reduced compared to healthy controls