Biological explanation : structural abnormalities

• Cerebellum: “Little brain” Responsible for motor control

  Brain stem: regulates automatic processes, and connects the brain to

  body

  Cerebrum (cerebral cortex) main part of brain
• Cortex: the thick top layer of the brain. Made up of a thin layer of neurons 2-4mm thick folded many times to give a huge surface area.

  Separated into two hemispheres, and each of these into four lobes.
• Each lobe has a number of functions

  The occipital lobe is responsible for vision, The temporal lobe responsible for language
• Under the cortex are many subcortical regions

  E.g: the Limbic system (including the hypothalamus, amygdala hippocampus) vital for emotion and memory

  Corpus callosum which connects the two hemispheres
• Emil Kraepelin (1856-1926) was one of the first psychiatrists to classify schizophrenia (or 'dementia praecox' as he called it). His view that schizophrenia was an organic brain disease was greatly overshadowed at the time by the much more popular views of Freud, Jung and other psychoanalysts. 
• However, with the advent of brain scanning technologies, modern researchers have produced much evidence to support Kraepelin's early ideas about brain disease, Identifying structural abnormalities in the brains of those with schizophrenia.
• ENLARGED VENTRICLES

  Ventricles are cavities that produce and transport cerebrospinal fluid.

  Cerebrospinal fluid is important as it provides protection, buoyancy and chemical stability to the brain and spine. There are four ventricles in the brain:

  • The left and right lateral ventricles (situated in the frontal, occipital and temporal lobes of their respective hemisphere).
  • The third ventricle is situated between the left and right thalamus.
  • The fourth ventricle lies between the pons and medulla oblongata.
• ENLARGED VENTRICLES

  In some individuals with schizophrenia, the ventricles seem to be larger than in those individuals without schizophrenia. Daniel Weinberger et al. (1979) used CAT scans and reported that ventricular size was greater in a group of 58 individuals with chronic (i.e. enduring) schizophrenia than the 56 in the control group of people with no symptoms of schizophrenia. 
• 40% of those with chronic schizophrenia were outside the range of the control group and 53% of those with chronic schizophrenia exceeded two standard deviations of the control group's mean score. Nancy Andreasen (1988) studied MRI scans of individuals with and without schizophrenia and found that those with schizophrenia had ventricles which were 20% to 50% larger than in controls.
• CORTICAL ATROPHY

  Cortical atrophy means the loss of neurons in the cerebral cortex Cortical atrophy can occur all over the brain (making it look like it has shrunk) or atrophy can be focused in a limited area. In the latter case, the atrophy obviously affects the cognitive functions of that area of the cerebral cortex. 
• CORTICAL ATROPHY

  The atrophy results in the widening of the grooves (called 'sulci) covering the cerebral cortex. This type of damage appears to characterise the brains of 20% to 35% of people with chronic schizophrenia.
• CORTICAL ATROPHY

  Antonio Vita et al. (1988) used CAT scans to assess 124 individuals with schizophrenia and 45 control group participants. They found that 33% of the individuals with schizophrenia showed moderate to severe atrophy. 
• Atrophy was not found to be related to many individual differences such as age, age of onset or family history, but it was found to be related to sex (specifically male) and if there was also ventricular enlargement.
• REVERSED CEREBRAL ASYMMETRY

  In most individuals without schizophrenia the left hemisphere is slightly larger than the right hemisphere (cerebral asymmetry). However, in some individuals with schizophrenia the right hemisphere is notably larger than the left (reversed cerebral asymmetry). 
• REVERSED CEREBRAL ASYMMETRY

  This is relevant when considering that language function is normally found in the left hemisphere, so damage or deterioration in the left hemisphere could lead to the poverty of language (alogia) which is often seen in schizophrenia.
• REVERSED CEREBRAL ASYMMETRY

  Daniel Luchins et al. (1979) compared, using CAT scans, 80 right-handed people without schizophrenia to 57 right-handed people with schizophrenia. 

  They found that there was an increase in the frequency of 'reversals' in both the frontal and occipital lobes of those with schizophrenia, but only in those who had no other form of atrophy. Those individuals with schizophrenia who had evidence of atrophy had no higher level of reversals than the control group.
• SEASON OF BIRTH

  Many factors have been linked to being possible 'neurodevelopmental' influences in schizophrenia. One of the most well-known is the 'season of birth' influence.
• A recent epidemiological study was conducted by Giulio Disanto et al. (2012) of almost 60,000 English patients diagnosed with schizophrenia, bipolar disorder and depression. 

  Schizophrenia was statistically more likely to be diagnosed in those participants born in January than those born in July, August or September. Researchers suggest the increased rates may be due to their expectant mothers being exposed to the flu virus or even suffering from a vitamin D deficiency while pregnant.
• SEASON OF BIRTH

  Epidemiological research such as this is very helpful as it shows that, although schizophrenia is seen by many as a biological disorder, there are most definitely environmental influences that can impact its prevalence.