Schizophrenia Flashcards
Facts on SZ
(AO2)
- mostly for ages 15-35
- affects 1% population
- ppl with family x10 more likely
classification of SZ ?
(categorising)
- DSM - 5
- ICD - 11
diagnosis of SZ with
DSM-5 v ICD-11
- DSM - 5
- 2 positive symptom must be present for diagnosis of SZ
- No sub-types - ICD - 11
- 2 or more negative symptoms must be present for diagnosis of SZ
- 7 sub-types
positive symptoms of SZ?
EG?
+ symptoms = additional experiences that the general population don’t experience
- Hallucinations - unusual sensory experiences
- Delusions - irrational beliefs
- Jumbled speech
Negative symptoms of SZ
- = the loss of usual abilities + experiences
- abilities which have been removed due to SZ that the general population have
-
Speech poverty - changes in patterns in speech
reduction in quality + amount of speech - Avolition - reduced motivation to begin / keep up with goal-directed activity, becoming disinterested
- Anhedonia - loss of ability to feel pleasure
- lack of emotion
reliability AO3:
Validity AO3:
- low reliability of classification - DSM5 + ICD11 not consistent
- low reliability of diagnosis - low inter-rater reliability
- may be explained by low resources + time
. - low validity = high co-mobility overlap of symptoms
- culture bias
- gender bias
Issues with Reliability of CLASSIFICATION of SZ
- classification of SZ is not reliable as the classification in DSM-5 + ICD-11 are not consistent.
- This is because the DSM-5 diagnoses SZ if 2 positive symptom is present and has no sub-types
- whereas the ICD-11 diagnosis SZ if 2 or more negative symptoms are present and it also has 7 sub-types of SZ
- Showing there is no consistency in the classification in SZ
1
Issues with Reliability of DIAGNOSIS of SZ
- Evidence which shows that the diagnosis of SZ is not reliable.
- Cheniaux et al had 2 psychiatrists independently diagnose 100 ps using DSM + ICD
- one diagnosed 2ps according to DSM + 44 according to ICD
- the other diagnosed DSM: 13 + ICD: 24
- = more SZ likely to be diagnosed under ICD than DSM and SZ is either over diagnosed with ICD or under diagnosed with DSM.
- Beck et al looked at inter-rater reliability between 2 psychiatrists when considering 154 ps
- the reliability was only 54% = only agreed on a diagnosis for 54% of the 154 ps.
Low inter-rater reliability may be explained..
- Different hospital have different resources + demand for number of patients = time availability differs
= could explain low inter-rater reliability, as these factors could explain differences in diagnosis by different psychiatrists
- As diagnosis made may not reflect true diagnosis of symptoms but rather may be as a result of it being rushed due to high demand for professionals as they have less time available
2
symptom overlap
- validity
(comorbidity = 2 conditions present at same time)
- SZ + bipolar disorder both share positive symptoms (e.g. delusions) + negative symptoms (e.g. avolition) = there’s symptom overlap
- depression + schizophrenia both involve very low levels of motivation = creates problems of reliability = Does low motivation reflect depression or schizophrenia / both?
- Using ICD, 1 patient might be diagnosed with SCZ but using DSM, would receive diagnosis of bipolar disorder = questions the validity of the classification of SZ
- Lack of distinction questions the validity of both classification/diagnosis of SZ
- = difficult to choose suitable diagnosis + treatment
- misdiagnosis due to symptom overlap = years of delay in receiving relevant treatment= suffering + high suicide levels can occur
- Symptom overlap can have serious consequences - focusing on fixing this issue could save money/lives = focus should not heavily be about the name of the disorder but rather the success of the relevant treatment they should receive
3
Culture bias (validity)
-further limitation of schizophrenia diagnosis is the existence of culture bias.
- Some symptoms of schizophrenia (auditory hallucination - hearing voices) have different meanings in different cultures.
- For example in some cultures some people believe that voices actually are communications from ancestors.
- British people of African-Caribbean origin are 9x as likely to receive a diagnosis as white British people, although people living in African- Caribbean countries are not = ruling out a genetic vulnerability.
- The most likely explanation for this is culture bias in diagnosis of clients by psychiatrists from a different cultural background.
- This appears to lead to an over interpretation of symptoms in black British people = British African - Caribbean people may be discriminated against by a culturally-biased diagnostic system
= Diagnosis is taking an ethnocentric approach, lowering the validity of the diagnosis of SZ.
4
Gender bias (validity)
- further limitation of schizophrenia diagnosis is the existence of gender bias.
- men are diagnosed with SZ more than women (ratio of 1.4 : 1 Fischer + Buchanan)
- A possible explanation for this is that women are less vulnerable than men, perhaps because of genetic factors.
- some behavior which was regarded as psychotic in males was not regarded as psychotic in females
- However it seems more likely that women are under diagnosed because they have closer relationships + hence get support (Cotton et al ). = so better able to manage symptoms = less severe = less diagnosed
- This leads to women with SZ often functioning better than men.
-This under diagnosis is a gender bias = lower validity + means women may not therefore be receiving treatment + services that might benefit them.
symptoms easily fakes + no predictive validity
- no predictive validity as there are no pathognomic symptoms
Biological explanations for SZ ?
- Genetic hypothesis
- Dopamine hypothesis
- Neural correlates
Genetic hypothesis:
- There is no SZ gene
- candidate genes associated with risk of inheritance
- SZ is polygenic
= different combinations of genes make individuals more vulnerable to SZ
Twin studies:
Cardno et al:
- found 40% concordance rate in MZ twins
- 5.3% in DZ twins
Family studies:
- General population 1% risk
Gottesman :
- the more genetically related a person to someone who has SZ = the higher risk they have
1st degree relatives: 6-9%
2nd degree relatives: 2-4%
3rd degree relatives: 2%
Kendler et al: 1st degree relatives 18x more at risk than general population
Adoption studies:
Tienari et al :
- children of SZ parents have higher risk of developing SZ even if adopted family have no history of SZ
AO3 genetic hypothesis:
- supporting evidence
- Nurture elements ignored
- reductionism
- Supporting evidence
- Supporting evidence : Tienari et al (adoption studies) + Gottesman (family studies) + Cardno et al (Twin studies)
= these show that some people are more vulnerable to SZ due to genetic makeup.
- Nurture elements
- Nurture (Environmental) factors have not been considered.
- As MZ twins share 100% genes, it would be expected that concordance rate would also be 100% if it was purely genetic
- As it’s only 40% - it suggests other influences (environment) are playing a part
- Also limitation of Gottesman study, is that the high concordance rate may be due to increased chance of sharing the same environment.
- EG 1st degree relatives may share exact same environment, whereas 2nd degree would not
= cannot be concluded that genetic has caused SZ.
- Reductionist
- The genetic explanation for SZ is reductionist.
- It has reduced SZ, which is a complex + serious psychologoical disorder to genetics.
- This allows researchers to investigate the genetic link for SZ in great detail + makes it more scientific.
- However, reductionism is negative as it oversimplifies serious behaviour into small simple components, making SZ seem very simple whilst realistically it is very complex and large.
Dopamine hypothesis
Dopamine neurotransmitters linked with SZ
- Both hyper + hypo are involved in onset of SZ
- hyperdopaminergia in subcortex :
- excessive levels of dopamine in subcortex
= positive symptoms
(Jumbled speech + auditory hallucinations) - hypodopaminergia in pre-frontal cortex :
- Low levels of dopamine in pre-frontal cortex
= negative symptoms
(to do with thinking + decision making as pre-frontal cortex responsible for that)
AO3 Dopamine hypothesis:
- Use of anti psychotic drugs for treating SZ
- opposing evidence
- Supporting evidence from PET scans + post postmortems