Transcript Schizophrenia: brain - King Edward VI Handsworth School

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How might genes contribute to a
psychological disorder?
How can we tell if a psychological disorder is
influenced by genetics?
Today’s session
You will learn about
Context
Interpreting
Schizophrenia
biological
data on the causes of
mental illness
The role of genetics and
brain structure &
processes in mental illness
Schizophrenia: genetics
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Prevalence is the same all over the world
(about 1%)
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Supports a biological view as prevalence does not
vary with environm nmm ent
However, there are variations within broad
geographical areas (e.g. Torrey 2002 – Croatia &
Ireland)
Urbanicity data
Schizophrenia: genetics
Source: Gottesman (1991)
Schizophrenia: genetics
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Risk rises with degree of genetic relatedness
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Spouse – 1% (same as G.P.)
Child – 13%
DZ twin – 17%
MZ twin – 48%
Effect of shared environment?
Schizophrenia: genetics
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Adoption studies
Prevalence amongst
biological relatives
Prevalence among
adoptive relatives
Kety et al (1968)
schizophrenia only
13%
2%
Tienari et al (1994) all
‘severe’ psych.
diagnoses
30%
15%
Schizophrenia: genetics
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Substantial evidence for a genetic
contribution
Some evidence disputed:
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Shared environment issues
Diagnostic criteria in adoption studies
All the evidence also suggests
environmental trigger
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Where would a bio-psychologist start looking
for the causes of schizophrenia (NB. be
careful!)?
What might they expect to find?
Schizophrenia: brain
Ventricular enlargement
Schizophrenia: brain
Cellular disarray
Schizophrenia: brain
Hypofrontality
Schizophrenia: brain
Grey matter loss (Thompson et al, 2001)
Schizophrenia: brain
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Evidence for neurological changes in
schizophrenia including:
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Loss of brain tissue
Ventricular enlargement
Cellular disarray
Low activity in frontal areas
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Is schizophrenia a brain disease?
Schizophrenia: brain
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No single abnormality common to all patients
Some indication that abnormalities correlate
with symptom types
Confounding effect of drug treatments are a
problem.
Overlap with normal population
Homework
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Evaluate the view that schizophrenia is a
genetic disorder (at least a side of solid
evaluative writing – use empirical evidence to
support your argument).
Briefly evaluate the view that schizophrenia is
a brain disease (one substantial paragraph).