Schizophrenia Flashcards
How do DSM-5 and ICD-10 differ in the diagnosis of schizophrenia?
DSM-5 = one positive symptom must be present.
ICD-10 = two or more negative symptoms are sufficient.
What does positive symptoms of schizophrenia mean?
Additional experiences beyond those of ordinary existence.
Give 2 positive symptoms of schizophrenia
1) Hallucinations - sensory experiences with no basis in reality or distorted perceptions of real things e.g. hearing voices.
2) Delusions - beliefs that have no basis in reality; changing behaviour that may make sense to schizophrenic but isn’t in reality e.g. believing one’s the victim of a conspiracy.
What does negative symptoms of schizophrenia mean?
Loss of usual abilities and experiences.
Give 2 negative symptoms of schizophrenia
1) Avolition - severe loss of motivation to carry out everyday tasks e.g. work = lower activity and unwillingness to carry out goal-directed behaviours.
2) Speech poverty (Alogia) - a reduction in the amount and quality in speech
Give 4 issues in the diagnosis of schizophrenia
1) Reliability - consistency of diagnosis.
2) Validity - extent to which diagnosis and classification measure what they are designed to measure.
3) Co-morbidity - occurrence of two illnesses together confusing diagnosis and treatment.
4) Symptom overlap - two or more conditions sharing symptoms questions validity of classification.
What did Cheniaux et al. (2009) find with the diagnosis of schizophrenia?
- It had low reliability.
- Two psychiatrists independently diagnosed 100 patients using both ICD and DSM criteria.
- Low inter-reliability.
- (1) 26 diagnosed with DSM and 44 with ICD.
- (2) 13 diagnosed with DSM and 24 with ICD.
How is the diagnosis of schizophrenia questioned validity wise?
- Cheniaux showed that Sz is much more likely to be diagnosed with ICD than DSM.
- Over-diagnosed in ICD or under-diagnosed in DSM?
= poor criterion validity.
A part from low validity and reliability, give a further limitation of the diagnosis of schizophrenia
1) Co-morbidity:
- two conditions = a single condition?
- Buckley et al. (2009) concluded half patients with Sz also have a diagnosis of depression (50%) or substance abuse (47%)
How is there gender bias in the diagnosis of schizophrenia
(i) Longenecker et al. (201) found that since the 1980s men have been diagnosed more often than women.
(ii) Cotton et al. (2009) - female patients typically function better than men = may escape diagnosis due to better interpersonal functioning.
What did Gottesman (1991) find the concordance rate of both schizophrenia was in MZ and DZ twins?
MZ = 48% DZ = 17%
How is schizophrenia polygenetic and aetiologically heterogeneous?
P = each gene confers a small increased risk of schizophrenia. AH = different combinations lead to schizophrenia
What did Ripke et al. (2014) find?
- 108 separate genetic variations associated with increased risk
How is dopamine (DA) involved with schizophrenia?
Featured in the functioning of brain systems related to the symptoms of schizophrenia
Hyperdopaminergia is linked with what areas of the brain which may lead to what symptoms?
- Subcortex.
- Hallucinations and speech poverty.
What is hyperdopaminergia?
High DA activity in the subcortex
What is hypodopaminergia?
Low levels of dopamine in the prefrontal cortex.
What can low levels of DA in the prefrontal cortex lead to?
Avolition.
Define neural correlates.
Measurements of the structure or function of the brain that correlate with the positive or negative symptoms of schizophrenia
How is avolition linked to the ventral striatum?
- VS involved in anticipation of reward (motivation)
= avolition explained by low levels here? - Juckel et al. (2006) found a negative correlation beween VS activity and overall negative symptoms.
In terms of neural correlates, what would a negative correlation mean?
- There is a correlation between an area of the brain and the negative symptoms of schizophrenia
What part of the brain are hallucinations believed to be linked with?
- Superior temporal gyrus.
- Allen et al. (2007) - patients experiencing auditory hallucinations recorded lower activation levels in this area and anterior cingulate gyrus.
What strong evidence is there for genetic vulnerability of schizophrenia?
- Gottesman with his family study of schizophrenia.
- Tienari et al. (2004) did an adoption study.
- Showed children of people with Sz are still at heightened risk of Sz if adopted into families without history of Sz.
How is there mixed support for the dopamine hypothesis?
- Dopamine agonists, e.g. amphetamoines, that increase increase DA can induced schizophrenic-like symptoms in people without Sz.
- Anti-psychotics that lower DA can be effective in reducing symptoms
- Some candidate genes responsible for production of other genes
= DA inadequate.