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Explanations for Schizophrenia (Biological (Evaluation (environment is…
Explanations for Schizophrenia
Biological
The genetic bases of Sz
Runs in family
:silhouette: Gottesman (1991)
as genetic similarity increases so does the probability of sharing Sz
Large-scale family study
Candidate genes
Polygenic - requires number of factors
Aetiologically hetergeneous
different combinations of factors lead to condition
:silhouette: Ripke et al (2014)
Genome-wide studies, genetic makeup of 37,000 compared to 130,000 controls, 108 separate variations w risk of Sz
Genes associated with increased risk included coding for functioning of a number of nt including dopamine
The dopamine hypothesis
Neurotransmitters
Chemicals work different w/Sz
Dopamine in functioning of several brain systems that may be implicated in the symptoms of Sz
Hyperdopaminergia in subcortex
High levels or activity of dompamine
Excess in Broca's associated with poverty of speech
Hyperdopaminergia in cortex
:silhouette: Goldman-Rakic et al (2004)
low dopamine in prefrontal cortex in negative symptoms
Abnormal dopamine systems in brain cortex
Neural correlates of Sz
Of negative symptoms
:silhouette: Juckel et al (2006)
Activity levels in ventral striatum in Sz and found lower levels of activity than those observed in controls
Negative correlation between
Of positive symptoms
:silhouette: Allen et al (2007)
those with auditory hallucinations and compared while identifying pre-recorded speech as theirs or others
Lower activation levels in the superior temporal gyrus and anterior cingulate gyrus were found in hallucination group, more errors
Reduced activity in two areas of brain is a neural correlate of auditory hallucination
Evaluation
Strong evidence for genetic vulnerability to Sz
:silhouette: Gottesman (1991)
Family study clearly shows how genetic similarity and shared risk of Sz are closely related
:silhouette: Tienari et al (2004)
Children of people with Sz are still heightened risk of Sz if adopted into history
Role of mutations supports the genetic explanation
:silhouette: Brown et al (2002)
Link between paternal age and risk of Sz, 0.7 under 25 2 over 50
Mixed support for dopamine hypothesis
some candidate genes code for production of other nt glutamate
dopamine cannot provide a complete explanation it is just one important factor
environment is also involved clearly
probability w twin is less than 50%
evidence that supports environmental influence
Sz is result of a combination of bio and psych
Psychological
Key terms
Family dysfunction
Abnormal processes within a family, may be risk factors for Sz
Cognitive explanations
Explanations on mental processes such as thinking, language and attention
Dysfunctional thought processing
Information processing that is not functioning normally and produces undesirable consequences
Family dysfunction
The schizophrenogenic mother
:silhouette: Frieda Fromm-Reichmann (1948)
Schizophrenogenic mother = schizophrenic-causing mother
Double bind theory
:silhouette: Gregory Bateson et al (1972)
Family climate is important in the development of Sz but emphasised communication styles
Seeing world as confusing and dangerous leads to disorganised thinking and paranoid delusions
Expressed emotion and Sz
Expresses emotion = the level of emotion expressed towards a patient by carer
Elements
Verbal criticism of patient, sometimes w/violence
Hostility towards patient, anger and rejection
Emotional over-involvement in the life of patient including needless self-sacrifice
High levels of EE = source of stress for patient
Can trigger onset of Sz in vulnerable person
Explanation for relapse of Sz
Cognitive explanation
Dysfunctional thought processing
Lower levels of information processing in some areas of the brain suggest cognition is impaired
Metarepresentation leads to hallucinations
:silhouette: Frith et al (1992)
Cognitive ability to reflect on thoughts and behaviour
Disrupts ability to recognise thoughts as our own
Dysfunction of central control leads to speech poverty
:silhouette: Frith et al
Central control being the cognitive ability to suppress automatic responses while performing deliberate actions
Words trigger association
Evalutation
Support for different information processing
:silhouette: Stirling et al (2006)
30 patients w 18 w/o cognitive tasks
twice as long to suppress impulse to read word
Family relationships often retrospective
:silhouette: Read et al (2005)
46 studies, 69% females w/Sz had childhood abuse
symptoms may have distorted recall of childhood
Evidence for family based is weak
Little evidence to support importance of family dysfunction
Mainly based on clinical observations
Cognitive explanation is direction of causality
Unclear whether cognitive factors are a cause of a result of neural correlates and abnormal nt levels in Sz
Questions validity of cognitive approach in explaining underlying origins