Schizophrenia L1 - 2 Flashcards
Schizophrenia:
Severe mental psychotic disorder characterised by disruption of cognition and emotion
Psychotic:
Mental issues causing abnormal thinking and loss of realism
Which 2 classification systems are used to diagnose schizophrenia?
- DSM 5 (America)
- ICD 11 (Europe and other parts of world)
Positive symptoms:
Symptoms that reflect an excess of normal functions
4 examples of positive symptoms:
- Hallucinations eg auditory, olfactory, tactile, visual
- Delusions
- Disorganised speech
- Grossly disorganised behaviour
Hallucinations v Delusions:
- Delusions are irrational beliefs
- Hallucinations are sensory experiences of stimuli
Negative symptom:
Symptom that reflects reduction of normal functions
3 examples of negative symptoms:
- Speech poverty (alogia) –> reduction in amount and quality of speech
- Avolition –> Loss of interest to do regular everyday tasks
- Affective flattening –> no emotional expression in their speech
How many of each type of symptom is needed to diagnose schizophrenia according to both classification system?
- DSM 5 –> 2 or more positive symptoms for a month and 6 months of social withdrawal
- ICD 11 –> 1 positive and one negative symptom for a month
Who made a distinction between two types of schizophrenia and what are each?
- Crow (1980)
- Type 1: Characterised more by positive symptoms
- Type 2: Characterised more by negative symptoms
Give 6 issues with the classification and diagnosis of SZ:
- Reliability
- Validity
- Co-morbidity
- Symptom overlap
- Gender bias
- Cultural bias
Give two studies showing weakness in reliability of diagnosis of SZ:
- Whaley (2001) found low inter rater reliability score of +0.11 (DSM)
- Cheniaux et al (2009)
- Read et al (2004)
Cheniaux et al (2009):
- 2 psychiatrists independently diagnose 100 schizophrenic patients using both ICD & DSM
- One psychiatrist diagnosed 26 (DSM) and 44 (ICD) w/ SZ
- Other psychiatrist diagnosed 13 (DSM) and 24 (ICD) w/ SZ
- Low inter-rater reliability
Read et al (2004):
Test-retest reliability showed 37% concordance rate of SZ diagnosis
Give one study showing strength in reliability of diagnosis of SZ:
- Flavia Osario et al (2019)
- Found inter rated reliability between pairs of psychiatrists was +0.97 and test-retest reliability was +0.92 (using DSM)
How can the validity of SZ diagnosis be assessed?
Using criterion validity (when different assessment systems arrive at the same diagnosis for some patient)
What does Chiniaux’s study show about validity of SZ diagnosis?
- Low validity
- SZ is more likely to be diagnosed w/ ICD than DSM
Give one study showing a reason for lack of validity in SZ diagnosis:
Rosenhan (1973)
Rosenhan (1973):
1) 8 volunteers who weren’t suffering from SZ presented themselves to different hospitals claiming they could hear voices
2) Took between 7 and 52 days to be released, diagnosed as schizophrenics in remission (DSM) (decreased symptoms)
3) Normal behaviours were interpreted as SZ symptoms
Rosenhan (1973) follow-up study:
1) Informed hospital that some number of pseudo patients would be admitted over 3 months
2) 83/193 admitted aroused suspicions of being false patients
3) No acc pseudo-patients were admitted
Give one study showing strength in reliability of diagnosis of SZ:
- Osario (2019)
- Because DSM reliability is so high, validity would also be high
- Suggests ICD needs more revision
Co-morbidity:
Idea that 2 or more mental disordered occur together at same time w/ same person
Give one study showing co-morbidity in SZ diagnosis:
- Buckley et al (2009)
- Around half of patients w/ SZ have also been diagnosed w/ depression/substance abuse
- PTSD also occurred in 29% and OCD in 23% of cases
Give one studies showing symptom overlap:
- Ellason and Ross (1995)
- Found that people with dissociative identity disorder acc have more schizophrenic symptoms than SZ diagnosed person
Give one study showing gender bias in SZ diagnosis:
- Fischer and Buchanan (2017)
- Since 1980s ratio of men and women diagnosed w/ SZ is 1.4 : 1
Give one study showing cultural bias in diagnosis:
- Pinto and Jones (2008)
- African American and English people of Afro-Caribbean descent are 9 times more likely to be diagnosed w/ SZ
Give two possible reasons for increased SZ diagnoses in black people:
- Auditory hallucinations may be acceptable there because of cultural beliefs in communication w/ dead ancestors but this is seen as a positive symptom of SZ in UK
- Possibly racism –> doubting honesty of black people (Escobar, 2012)
3 advantages of diagnosis of SZ:
- Communication shorthand –> simpler to incorporate symptoms into single diagnosis to communicate between professionals
- Easier to identify a treatment
- Many w/ SZ have underlying biological abnormalities, which can lead to more effective treatment if diagnosed
What 2 explanations does the biological approach include?
- Neural correlate including dopamine hypothesis
- Genetics
What 3 types of studies usually test genetic factors?
- Family
- Twin
- Adoption
What have family studies shown about the effect of genes on the risk of getting schizophrenia?
The closer the genetic relations, there more likely you are to get schizophrenia
Gottesman (1991):
- If both parents are schizophrenic, the likelihood of the offspring also having SZ was 46%
- If one parent is schizophrenic, the likelihood of offspring having SZ is 9%
- 48% concordance rate for MZ twins
- 17% concordance rate for DZ twins
Joseph (2004):
- Review of twin studies carried out up to 2001
- Found concordance rate for MZ is 40%, whereas DZ is 7.4%
Tienari et al (2001):
- 164 adoptees w/ SZ biological mothers, where 6.7% were diagnosed with SZ
- Compared to control grp of 197 adoptees where 2% had SZ
- Link between genes and schizophrenia
Is schizophrenia polygenic or monogenic and which studies showed this?
- Polygenic
- Gurling et al (2006), Benzel et al (2007), Ripke et al (2014)
Gurling et al (2006):
- Used family study evidence to show that SZ was associated w/ chromosome 8p21-22
- Used gene mapping to show PCM1 gene was also implicated in being susceptible to SZ
Benzel et al (2007):
Used gene mapping suggesting that NRG3 gene variants interact w/ NRG1 and ERBB4 gene variants to create susceptibility to SZ
Ripke et al (2014):
- Compared genetic makeup of 37000 SZ patients worldwide w/ 113000 controls
- 108 separate genetic variations were associated with SZ
- Those that were particularly vulnerable had some connection to certain neurotransmitters
Strengths and weaknesses of genetic explanation for SZ: (+1, -4)
+ Research evidence –> Gottesman, Tienari, Joseph, Benzel, Ripke, Gurling
- Nature or nurture? –> even in adoption studies, often children are brought up by relatives who have similar rearing styles
- SZ can occur despite having no family history –> Brown et al (2002)
- Biologically reductionist –> ignores other factors and insinuates having the gene will mean SZ
- Diathesis stress model
How can SZ occur despite there being no family history and what study shows evidence for this?
- Mutation in parental DNA
- Brown et al (2002)
Brown et al (2002):
- Positive connection between paternal age and increased risk of SZ
- From around 0.7% in fathers under 25 to over 2% in fathers over 50
What does the diathesis stress model suggest about vulnerability to SZ?
Genes can make you more vulnerable, however this is only likely to be triggered if there is a stress trigger in the individual’s life
Neural correlates:
Patterns of structure/activity that occur in conjunction with an experience and may be implicated in the origins of this
What structural changes have been shown within schizophrenics and which study showed each?
- Enlarged ventricles –> Torrey (2002)
- Impaired prefrontal cortex –> Weinberger and Gallhofer (1997)
- Changes in hippocampus –> Conrad et al (1991)
Torrey (2002):
Ventricles of someone w/ SZ is on avg abt 15% larger than normal
Give 2 characteristics of a person w/ enlarged ventricles:
- More negative than positive symptoms
- Respond poorly to antipsychotic drugs
What is the role of the prefrontal cortex?
Involved in executive control
Conrad et al (1991):
Anatomical changes have been reported in hippocampus of SZ patients
Strengths and weaknesses of neural correlates as an explanation for SZ: (+2, -3)
+ Research evidence –> Torrey, Weinberger and Gallhofer, Conrad et al
+ Face validity due to the availability of brain scanning, helping to tailor treatments
- Individual differences
- Cause and effect
- Difficult to pinpoint exact brain region causing the issue
Give two functions of dopamine as a neurotransmitter:
- Helps regulate movement, attention, learning and emotional responses
- Contributes to feelings of pleasure
According to the dopamine hypothesis, what do schizophrenics have too much of, which causes their symptoms?
- D2 receptors
- Leads to more dopamine binding and neurons firing
2 consequences of dopamine hypothesis:
1) Hyperdopaminergia –> high levels of dopamine in subcortex
2) Hypodopaminergia –> low levels of dopamine in cortex
Strengths and weaknesses of dopamine hypothesis as explanation for SZ: (+1, -2)
+ Drug research evidence –> dopamine agonists like amphetamines increase dopamine and worsen SZ symptoms, Tauscher et al (2014), Lindstroem
- Biologically determinist –> Moghadamm and Javitt (2012)
- Correlation-causation issue –> doesn’t mean high dopamine causes SZ, just a link
Tauscher et al (2014):
Antipsychotic drugs reduce levels of dopamine in SZ patients, controlling SZ symptoms
Lindstroem et al (1999)
Chemicals needed to produce dopamine are taken up faster in schizophrenics’ brains compared to controls
Moghadamm and Javitt (2012):
- Found that glutamate had been implicated in SZ
- Excessive release of glutamate leads to cognitive impairments
