schizophrenia P3 Flashcards
definition of schizophrenia
severe mental disorder where contact with reality and insight are impaired
definitions of positive symptoms
atypical symptoms experienced in addition to normal experiences
e.g. Hallucinations
definition of negative symptoms
atypical experiences that represent a loss of usual experience
e.g. loss of clear thinking
prevalence of schizophrenia
serious mental disorder affecting 1% of population
more common in males, city-dwellers and lower socio-economic groups
diagnosis
diagnosis & classification = interlinked
to diagnose we must be able to distinguish one disorder from another
classification = identify symptoms that go together to form a disorder
diagnosis == identify symptoms and use classification systems to identify the disorder
DSM-5 & ICD-10 differences
- DMS-5 = one positive symptom must be present
- ICD-10 = two or more negative symptoms are sufficient for diagnosis
Hallucinations - positive symptoms
unusual sensory experiences that have no basis in reality or distorted perceptions of real things
experienced in relation to any sense
e.g. hearing voices
Delusions - positive symptoms
beliefs that have no basis in reality
make person behave in ways which make sense to them but unusual to others
e.g. believing that they are napoleon
Speech poverty - negative symptoms
a reduction in the amount & quality of speech
can be a delay in verbal responses during conversation
but speech disorganisation = positive symptom
Avolition - negative symptoms
a severe loss of motivation to carry out everyday tasks e.g. personal care
Resulting in lowered activity levels & unwillingness to carry out goal-directed behaviours
S of diagnosis of schizophrenia is good reliability
a reliable diagnosis between clinicians and between occasions.
-> Osorio 2019, reported excellent reliability for schizophrenia diagnosis as the inter-rater agreement was +0.97 and test retest reliability of +0.92
This means that diagnosis of schizophrenia is consistently applied
A limit of diagnosis is low validity
criterion validity involves seeing whether different procedures used to assess the same individuals arrive at the same diagnosis
->Cheniaux 2009, 2 psychiatrists independently assess the same 100 clients, 68 were diagnosed with ICD & 39 with DSM
This means that schizophrenia is either over or under diagnosed, suggesting that criterion validity is low.
Another Limit of diagnosis is co-morbidity with other conditions
if conditions co-occur then they might be a single condition -> Sz diagnosed w other conditions.
Buckley 2009 concluded that Sz is co-morbid with depression (50%), substance abuse (47%) & OCD (23%)
This suggests that Sz may not exist as a distinct condition
a limit of diagnosis is culture bias
some symptoms e.g. hearing voices are accepted in some cultures like Afro-Caribbean societies ‘ hear voices from ancestors’ -> Afro-Caribbean British men are 10X more likely to receive a diagnosis as white men -> due to overinterpretation of symptoms by UK psychiatrists.
This means that Afro-Caribbean men living in the UK appear to be discriminated against by a culturally-biased diagnostic system .
Family studies -genetic basis of Sz
a strong relationship between the degree of genetic similarity and shared risk of schizophrenia.
Gottesman 1991
Gottesman 1991
large scale study
for fraternal twins there is a 17% likelihood that if one is diagnosed, the other may develop it
but, identical twins it is 48% & for siblings it is 9%
-can share environment but indicates support for genetic view
Candidate genes - genetic b
Schizophrenia is polygenic - requires several genes to develop
aetiologically heterogeneous - the risk of developing Sz is affected by a combination of genes
Ripke 2014
combined previous data from genome-wide studies
found 108 separate genes associated with slightly ^ risk of schizophrenia
Mutation - genetic basis
Sz can have a genetic origin in absence of family history due to mutation in parental DNA
-evidence comes from correlation between paternal age & risk of schizophrenia
Brown 2002
evidence for sperm mutation being correlated with the risk of sz
increasing from 0.7% under 25 fathers to over 2% fathers over 50
A strength for the genetic basis is the strong evidence base
family studies e.g. Gottesman show risk increases with genetic similarity. Hilker 2018 Twin study found 33% in MZ twins & 7% for DZ twins.
Tienari 2014, adoption studies show that biological children of parents w SZ are at greater risk even if they in adoptive family.
-> This shows that some people are more vulnerable to sz because of their genes
A limitation for the genetic basis is evidence for environmental risk factors
Biological risk factors include both complications and smoking THC rich cannabis in teenage years ->Psychological risk factors include childhood trauma e.g. 67% w Sz reported at least one childhood trauma.
->this means genes alone can’t provide a complete explanation for schizophrenia
Neural correlates
measurements of the structure or function of the brain that occur in conjunction with an experience
Dopamine- neural correlates
believed to be involved
it’s featured in the functioning of brain systems related to symptoms of schizophrenia
Original Dopamine hypothesis
high dopamine activity in subcortex -> hallucinations & speech poverty
can explain positive symptoms
‘Hyperdopaminergic’
Hyperdopaminergia
excessive levels of dopamine in the subcortex and broca’s area
Hypodopaminergia
low levels of dopamine in prefrontal cortex
Updated dopamine hypothesis
low levels of Dopamine in the prefrontal cortex can explain negative symptoms
explains origin of abnormal dopamine - genetic variations & experiences of stress can ppl more sensitive to cortical hyperdopaminergia -> subcortical hypodopaminergia
Strength for neural correlates is the support for dopamine in the symptoms of schizophrenia
Amphetamines mimic symptoms (Curran 2004) Antipsychotic drugs reduce intensity of symptoms (Tauscher 2014)
Candidate genes act on the production of Dopamine or dopamine receptors
-> this strongly suggests that dopamine is involved in the symptoms of schizophrenia
A limitation for neural correlates is evidence for a central role for glutamate
Post-mortem and scanning studies found raised glutamate in people with schizophrenia (McCutcheon 2020)
several candidate genes for Sz are believed to be involved in glutamate production or processing
-> this means that a strong case can be made for a role for other neurotransmitters in schizophrenia.
What is family dysfunction?
A psychological explanation for Sz composed of: Schizophrenogenic Double bind theory Expressed emotion
Schizophrenogenic mothers
-Fromm- Reichmann 1948
-psychodynamic approach
‘Schizophrenia causing’
mothers are cold, rejecting and controlling -> family climate of tension & secrecy -> child is distrusting -> develop paranoid delusions -> Schizophrenia
Double bind theory
conflicting family communication
Bateson 1972
a child who feels trapped in situations where they fear doing the wrong thing -> receive conflicting messages about what counts as wrong -> can’t express their feelings of unfairness -> if get it wrong parents withdraw love -> learn world is confusing & dangerous ->disorganised thinking & delusions
Expressed emotion
criticism and hostility -> relapse
the high level of emotion expressed including; Verbal criticism, Hostility, Emotional over-involvement in their life
-> stress in Sz sufferer -> relapse
A strength for family dysfunction is the evidence links to schizophrenia
Read 2005, reported that adults with schizophrenia are disproportionately likely to have insecure-attachment. Also 69% of women and 59% of men with Sz have experienced physical or sexual abuse.
-> This strongly suggests that family dysfunction does make people more vulnerable to Sz.
A limit for family dysfunction is the poor evidence base for any explanation.
there is almost no evidence to support the importance of traditional family-based theories e.g. Double bind, Schizophrenogenic mother.
Both theories are based on clinical observation of patients and informal assessment of the personality of the mothers.
-> This means that family explanation have not been able to explain the link between childhood trauma and Sz
