Evaluation

• ARE THE FINDINGS REPLICABLE?

  Robert McCarley and colleagues (1999) claim that the presence of enlarged ventricles in people with schizophrenia is the most reliable finding in research that uses brain scans. The link between cortical atrophy and schizophrenia has also been confirmed (e.g. Flashman and Green, 2004). However, structural abnormalities have not always been found and reproduced in studies of individuals with schizophrenia.
• ARE THE FINDINGS REPLICABLE?

  McCarley et al. suggest factors such as the age, sex and severity of symptoms can all 'exert a powerful influence on the prevalence and pattern of the observed brain abnormalities. This suggests that either structural abnormalities are only evident in some of those individuals diagnosed with schizophrenia or that we need to acknowledge more subtle differences when assessing structural abnormalities.
• ARE THE FINDINGS REPLICABLE?

  McCarley et al. also mention how patients are assessed as a factor. Subtle differences in the ways in which brain structure is measured by different researchers may be responsible for some of the subtle and not-so-subtle differences detected in the structural abnormalities.
• A CAUSE OR EFFECT OF SCHIZOPHRENIA

  As with the dopamine hypothesis, it is unclear whether structural abnormalities are the cause of schizophrenia or an effect of having schizophrenia. Although most researchers would probably argue that at least some structural abnormalities are a cause, we have to remember that environmental influences can significantly impact brain tissue. 
• A CAUSE OR EFFECT OF SCHIZOPHRENIA

  For example, Kenneth Lyon et al. (1981) reported that as doses of antipsychotic medications increased in their sample of participants, the density of brain tissue decreased. This suggests that perhaps after schizophrenia has been diagnosed and is treated with antipsychotic medications, the medication is what actually causes some structural abnormality such as enlarged ventricles.
• STRUCTURAL ABNORMALITIES ARE NOT ONLY LINKED TO SCHIZOPHRENIA

  Structural abnormalities are not only present in those individuals with schizophrenia, but are also found in individuals with other conditions. Paul Roy et al. (1998) note that individuals diagnosed with bipolar disorder and schizoaffective disorder have also been found to have enlarged ventricles. Disorders such as bipolar disorder and schizophrenia have many overlapping symptoms and this may be the result of similar structural abnormalities in the brain.
• STRUCTURAL ABNORMALITIES ARE NOT ONLY LINKED TO SCHIZOPHRENIA

  However, this may indicate either that these disorders have a similar causation or that perhaps the way we have classified these different conditions needs to be reviewed. Perhaps as brain scanning techniques become more refined, diagnosis may actually become reliant on the scans which indicate structural and functional abnormalities, rather than just the resultant behaviour.
• NEURODEGENERATIVE OR NEURODEVELOPMENTAL

  It is unclear if the structural abnormalities noted in the brains of some individuals with schizophrenia are caused by neurodevelopmental factors (such as exposure to noxious agents or events in utero, in early childhood or adolescence) which hinder healthy brain development or if they are due to neurodegenerative causes, the result of progressive brain changes, such as the loss of cortical tissue (a process that occurs in all of us as we age).
• NEURODEGENERATIVE OR NEURODEVELOPMENTAL

  Some researchers (e.g. Mathalon et al., 2003) even claim that structural abnormalities seen in people with schizophrenia are the result of a combination of both neurodevelopmental and neurodegenerative factors, neurodevelopmental factors impair cortical development and then this cortical impairment makes the individual more susceptible to neurodegenerative processes.
• BRAIN SCANNING

  There are many different ways to scan your brain. When detecting structural abnormalities, perhaps the most widely used scan is MRI (magnetic resonance imaging).
• BRAIN SCANNING

  MRI uses radio waves and magnetic fields to create cross-sectional images of any part of the body, including the brain. Different tissues and substances in different parts of the body have different water content and magnetic properties, hence differences in the signals detected by the MRI machine will allow for the different tissues and structures to be distinct from one another.
• For some scans, a contrast agent might be used; this is a magnetically active substance that is helpful in showing structural abnormalities more clearly.MRIs give more detailed images of the body than other similar scans such as computerised axial tomography (CAT) scans or X-rays.
• MRIs are also less damaging than CAT scans as MRIs do not use ionising radiation, which is used by CAT scanners. However, because of the use of strong magnetic fields, individuals with pacemakers or implanted devices cannot receive one. The device would heat up or could be drawn towards the magnet.
• MRI (functional  MRI) uses MRI technology to detect changes in the blood flow to areas of the brain. In this way brain activity can be assessed.