Brain Structure (20)

• intro Schizophrenia is associated with changes in the structure & functioning of the brain; regions including the prefrontal cortex and medial temporal lobe which are involved in memory and decision making. Crow (1985) suggests that the differences in brain structure between schizophrenics and non schizophrenics relate to the distinctions between positive & negative symptoms. He concluded that negative symptoms relate to brain structure and positive symptoms are better explained using neurotransmission.
• 1; AO1:

  •  CAT scans have shown that people with schizophrenia have a smaller overall brain volume and enlarged ventricles (15% bigger), implying a loss of brain cells.
  •  Ventricles are fluid filled cavities caused by the death of tissue that supply oxygen and blood to neurons.
  •  no gliosis (scar tissue) left in the brain and ventricles do not get larger which indicates that sz is not progressive.
• 1; AO3:

  •  strength: Pahl, Swayze & Andreasen found that in 50 studies, the majority of patients with Sz had abnormally large ventricles, this suggests that the loss of brain cells and expansion of brain fluid links to having Sz and could result in symptoms such as auditory hallucinations or delusions of grandeur.
• 1; AO3:

  •  weakness: data obtained in studies researching Sz is correlational, brain dysfunction such as enlarged ventricles may be a symptom; the plasticity of the brain means it may change due to abnormality. Therefore, a cause and effect relationship between brain structure and Sz cannot be established
• 2; AO1:

  •  Reduced grey matter volume and disrupted white matter integrity is suggested to link to Sz and they may be progressive during pre and post onset of the disorder.
  •  Changes are observed on functional imaging techniques, identifying abnormal neural activity.
  •  MRIs show reduced grey matter in the medial & superior temporal & prefrontal regions.
• 2; AO3:

  •  strength: objective measures are used to obtain data, MRI techniques are non-invasive/ionising which means images can be acquired repeatedly in awake ppts. Researchers interpret results in the same way so findings are credible & objective, showing high resolution images of internal structures.
  •  weakness: may lack generalisability, using fMRI scans means people with metal implants cannot have one, and pregnant people cannot use PET scans, the findings are limited to the samples used which may not be representative of a wider population of people with schizophrenia.
• 3; AO1:

  •  prefrontal cortex, located in the frontal lobe, is responsible for executive functions such as decision making and problem solving
  •  Sz patients show reduction of grey matter in the PFC and reduced metabolic rates due to an excessive dopamine release
  •  They have poor working memory and language processing which explains delusions & poor logical thinking
• 3; AO3:

  •  strength: Goldstein scanned the entire brains of those with Sz using matched pairs on age, sex and ethnicity, finding that the greatest reduction of brain matter was in the paralimbic cortex and middle frontal gyrus. These regions were significantly smaller than controls, this suggests that brain deficits explain the symptoms of Sz including negative symptoms (social withdrawal, low mood) and positive symptoms (hallucinations).
• 3; AO3:

  •  weakness: only considers biological factors, ignoring the contribution of psychological/environmental factors - neurodevelopmental hypothesis suggests that during the womb, birth process or after birth, there are factors which cause brain lesions and increase vulnerability to Sz, Wright et al found an incidence of Sz in children born to mothers who had flu during pregnancy. Therefore, we should consider more than one level of explanation as the biological explanation is reductionist.
• 4; AO1:

  •  Damage during foetal development can increase vulnerability to Sz as suggested by the neurodevelopmental hypothesis
  •  Factors during the womb, birth process or after birth can cause brain lesions, including being born in winter or the mother being malnourished or having flu during pregnancy.
• 4; AO3:

  •  strength: in Helsinki there was a positive correlation between Sz rates and exposure to influenza, people exposed to the virus during the second trimester had much higher rates than those not exposed, this highlights the importance of cortical development in growth during the second trimester, suggesting that brain deficits have a direct link with the development of Sz
• 4; AO3:

  •  weakness: Battle et al - in 12,000 Sz patients and 735000 controls there was no correlation between the incidence of Sz and prevalence of measles/flu in the gestation period, this suggests that exposure to illnesses/viruses during foetal development does not cause brain deficits that lead to schizophrenia
• 5; AO1:

  •  basal ganglia - group of subcortical nuclei located in the temporal lobe, responsible for motor control
  •  has a connection to the prefrontal cortex, linking to motivation, reward & dopamine production
  •  lack of activation in the basal ganglia in Sz patients and a larger volume which corresponds with the motor symptoms typical of Sz.
• Conclusion:

  •  weakness: deterministic, it suggests that brain deficits cause the symptoms of Sz and that people have no free will, an alternate theory might be the diathesis stress model. People may be predisposed to brain dysfunction but the abnormality doesn’t result in Sz unless it interacts with the environment. This accounts for the lack of consistency in findings of brain dysfunction.
• Conclusion:

  •  strength: useful applications - theories which demonstrate the cause of a disorder can lead to formulation of relevant treatment; research demonstrates that brain dysfunction can be reduced with drug treatment, this will improve the individual’s quality of life by alleviating symptoms & allow them to become stable and independent