Paper 3 - Schizophrenia Flashcards
What is schizophrenia?
A serious mental disorder suffered by about 1% of the population.
- more commonly diagnosed in men than women
- more commonly diagnosed amongst the working class
- sufferers may find their symptoms to dramatically interfere with everyday life
How does ICD-10 diagnose schizophrenia?
- requires two or more negative symptoms
- loss of usual abilities and experiences
- Avolition: decreased motivation, signs include poor hygiene, lack of persistence and energy
- Speech poverty: changed patterns of speech (delayed convo)
- recognises the subtypes of schizophrenia:
paranoid - delusions and hallucinations
hebephrenic - primarily negative symptoms
catonic disturbance in movement
How does the DSM-5 diagnose schizophrenia?
- believes it would be at least one positive symptom or one negative symptom (for over a month)
- Hallucinations: unusual sensory experiences where voices are heard (critical) or seen (senses)
- Delusions: paranoia and irrational beliefs; tend to involve religious, political figures (Jesus). May believe there is strong external control (government or aliens)
What is the difference between negative and positive symptoms?
Positive symptoms tend to be additional experiences beyond ordinary existence whereas negative involves the loss of usual abilities
Evaluate the methods of diagnosing schizophrenia
Poor reliability:
- Cheniaux had two psychiatrists independently diagnose 100 patients using both ICD-10 and DSM-5 crriterias
- poor inter-rater reliability; one said 26 (DSM) and 44 (ICD) and the other found 13 (DSM) and 24 (ICD)
- this poor reliability shows the methods of diagnosis are poor
Invalid:
- Chineaux’s study suggests that schizophrenia is more likely to be diagnosed with ICD than DSM
- the assessments do not arrive at the same diagnosis and therefore are not measuring what they are intending to; thus poor validity
Co-morbidity:
- two conditions occurring together; if this happens frequently, it questions validity of the diagnosis
- Buckley concluded that half of the patients with diagnosis of schizophrenia also had depression or substance abuse. PTSD also occurred in 29% of the cases
- difficult to tell the differences between conditions - or it could be a single condition
Culture bias:
- those with Afro-Caribbean origin are more likely to be diagnosed with schizophrenia that white people (but rates within Africa and West Indies are not that high; not genetic vulnerability)
- some positive symptoms (e.g. hearing voices) are more acceptable in African cultures (communication with ancestor) - these symptoms are often overlooked by white psychiatrists who tend to distrust black people (Escobar et al)
- forms of imposed etic
Describe schizophrenia running in families (genetic basis- bio)
- schizophrenia appears to run in families but it is difficult to determine as families tend to share aspects of the environment
- systematic investigations have suggested that the greater the genetic similarity between family, the greater the chance of both developing schizophrenia
- 100% genes shared between Mz twins but 50% with Dz twins - therefore Mz have greater genetic similarity and shared risk of schizophrenia
Gottesman’s family study= identical twins had 48% probability of sharing schizophrenia whereas first cousins is 2% - therefore supporting the assumption
Describe how candidate genes may cause schizophrenia (genetic basis - bio)
Candidate genes: individual genes are believed to be associated with risk of inheritance
- small number of genes appear to confer a small increased risk of schizophrenia: polygenic as it requires a number of factors to work in combination for it to manifest
- appears to be aetiologically heterogeneous - different combinations of factors = condition
- Ripke studied 37000 patients compared to 113000 controls and found there to be 108 separate genetic variations associated with the increases risk of schizophrenia (tended to code for neurotransmitters like dopamine)
Give strengths for the genetic explanation for schizophrenia (bio)
- strong evidence for genetic vulnerability to schizophrenia from different sources
- Gottesman’s study shows how genetic similarity and shared risks of schizophrenia are closely related
- Tienari’s adoption study showed that children of schizophrenia sufferers were still at a heightened risk of schizophrenia even when adopted into families with no history of the condition
- Ripke - molecular level - particular genetic variations significantly increase the risk
- parsimony ; isolation of one simplistic explanation - allows us to make treatments leading to positive applications for biological reductionism
Overwhelming support for the idea of genetics making an individual more vulnerable but does not mean it is entirely genetic as it could be the interaction with the environment causing the condition (diathesis-stress)
Describe the dopamine hypothesis (bio)
Dopamine is a neurotransmitter that is important in brain systems and may be implicated in the symptoms of the schizo
Hyperdopeminergia in subcortex: original hypothesis suggested that high levels of dopamine in the subcortex and in excess in the Broca’s area (speech production) are associated with negative symptoms (speech poverty) or auditory hallucinations
Hypodopaminergia in the cortex: recent hypothesis focuses on abnormal dopamine systems in the brain’s cortex: Goldman-Rakic identified the role of low levels in the prefrontal cortex are responsible for negative symptoms
Evaluate the dopamine hypothesis (bio)
Mixed evidence
- Support: dopmaine agonists like amphetamines increase levels of dopamine and make schizophrenia worse and may produce schizophrenia-like symptoms in non-sufferers
- furthermore, antipsychotic drugs work to reduce dopamine activity
- radioactive labelling studies found that the chemicals needed to produce dopamine are taken up faster in the brains of schizphrenics than controls
- both suggest the importance of dopamine in schizophrenia
Weakness: REDUCTIONIST
Some of the genes in Ripke’s study code for the production of other neurotransmitters so suggests dopamine is not the only factor (e.g. glutmate appears to hold a more significant effect in more recent research)
Describe how neural correlates affect schizophrenia (bio)
- neural correlates measure structure or function of the brain that correlate with experience - positive/negative symptoms have neural correlates
Negative symptoms: avolition involves loss of motivation which involves the ventral striatum which is believed to be involved in anticipation for rewards
- therefore abnormality in the ventral striatum = negative symptoms
- Jucket et al = low levels of activity in ventral striatum in schizophrenics rather than controls (observed negative correlation between ventral striatum and severity of negative symptoms)
Positive symptoms: Allen et al scanned the brains of patients experiencing hallucinations and compared to control group whilst they identified recorded speech
- lower activity in the superior temporal gyrus and anterior cingulate gyrus were found in the hallucination group - and they also made more errors
Evaluate research in neural correlates
correlation-causation
- does the unusual activity cause the symptom?
- it could be other factors influencing the ventral striatum
- or it could be that the negative symptoms cause less info to pass through the striatum resulting in less activity
Evaluate biological explanations for schizophrenia as a whole
- ignores nurture and psychological explanations
- could be effected by social/ environmental factors ]
- therefore the approach needs to be more holistic and inclusive of other theories
How are antipsychotics involved in treating schizophrenia (bio treatments)?
- taken as tablets or in syrup form or may be injections
- required in the short or the long term
- typical and atypical
Describe typical antipsychotics (bio treatments)
- around since the 1950’s and include chlorpromazine (syrup, tablet, injection) - small doses gradually increase (max 1000mg)
- associated with the dopamine hypothesis and work as dopamine antagonists as they block dopamine receptors in the synapses, reducing the action)
- initially, may cause build up but will eventually reduce
- reduces symptoms and is also an effective sedative as relates to histamine receptors