Structual Abnormalities Flashcards
What are the three main focuses in the structural abnormalities explanation?
Enlarged ventricles
Cortical atrophy
Reversed cerebal asymmetry
What are ventricles?
Cavities that transport cerebrospinal fluid (providing protection and stability for the brain and spine)
What are the four ventricles?
- The left lateral ventricle
- The right lateral ventricle
- The third ventricle (between left and right thalamus)
- The fourth ventricle (between the pons and medulla oblongata)
Explain a supporting piece of evidence for the theory of enlarged ventricles in schizophrenia sufferers?
Weinberger used CAT scans finding ventricular size was greater in a group of 58 individuals with chronic schizophrenia compared to 56 in the control group
What is a weakness of Weinbergers research?
Small sample size - low external validity
Inability to establish cause and effect - only correlation
Not for every schizophrenia sufferer
What is cortical atrophy?
The loss of neurons in the cerebral cortex, it can occur all over the brain making it look as though it has shrunk OR in one particular area affecting the function linked to the area
Atrophy widens the grooves covering the cerebral cortex
Why do we need to be careful making assumptions surrounding cortical atrophy?
Damage only appears in 20%-30% of sufferers
Vita used CAT scans to assess 124 individuals with schizophrenia and 45 controls. What did Vita find?
33% of people with schizophrenia had severe atrophy - not related to age or family history but appeared to be related to gender (mainly males)
Why is Vitas research only considered a partial explanation?
Because the statistic is moderate indicating that atrophy is not the only cause of schizophrenia - may be an effect rather than casual factor
What is the theory of reversed cerebral asymmetry?
Most people without schizophrenia have a left hemisphere slightly larger than the right. In some individuals with schizophrenia this is reversed
Why is the idea of reversed cerebral symmetry relevant to schizophrenia?
Language formation is often linked to the left hemisphere so the damage here could lead to the poverty of language (ALOGIA)
Where did support for reversed cerebral asymmetry come from?
Luchins
Compared CAT scans of right and left handed people with schizophrenia to controls and found an increase in the frequency of reversals in both frontal and occipital ones of those with schizophrenia when there was no other form of atrophy
Why is cause and effect an issue for this explanation?
Because it’s possible the brain adapts to try and cope with schizophrenic symptoms therefore structural abnormalities are an effect rather than a cause of the illness
What did Lyon et al find?
That as antipsychotic medication dosage increased - so did the density of brain tissue indicating medication may in fact cause abnormalities therefore is an effect
Why is cause and effect of schizophrenia nearly impossible to establish?
We live in a society mindful of human rights so cannot test and study all individuals e.g. scanning brains of babies is unethical as it could lead to isolation and discrimination
What did Roy et al find?
Individuals diagnosed with bipolar disorder and schizoaffective disorder also have enlarged ventricles - could be down to overlapping symptoms within the DSM-5
Why does diagnostic criteria need to be reviewed?
Suggest disorders have a similar cause and the differences between cultures and diagnosis is worrying due to overlapping symptoms
Why would brain scanning techniques becoming more refined be a strength of diagnostic criteria?
Diagnosis could be based in a scan rather than observation of subjective behaviour
Are the findings of structural abnormalities reliable?
McCarley and colleagues claim the presence of large ventricles in schizophrenia sufferers is the most reliable finding in research using brain scanning
The link between atrophy and schizophrenia has also been confirmed
HOWEVER
Structural abnormalities are not found in every sufferer leading to questions about the reliability of these findings
Why should brain scanning techniques focus on more subtle differences?
Would improve reliability as factors such as age and gender can affect the pattern of observed abnormalities e.g. if structural abnormalities are an effect than a 70 year old sufferer would have a much different scan to a 15 year old sufferer
The assessment should remain consistent for all researchers
Why might structural abnormalities be linked to neurodevelopment?
exposure to noxious agents or events in utero, childhood or adolescence hindering healthy brain development
What did Distantos research of 60,000 patients find?
That schizophrenia was more prevalent in people born in January - could be due to mothers exposed to the flu virus or suffering from vitamin D deficiency in later stages of pregnancy
Why is Distantos research important?
Shows that environmental factors can influence the prevalence of the disorder
What is a weakness of Distantos research?
Only correlational
Most people born in January do not develop schizophrenia - limiting the usefulness of the supporting evidence
