Schizophrenia Flashcards
(195 cards)
What is schizophrenia?
- A serious mental disorder experienced by about 1% of the world population.
- It is more commonly diagnosed in men, city-dwellers and lower socio-economic groups
- The symptoms of schizophrenia can interfere severely with everyday tasks, so that many people with it can end up homeless or hospitalised.
What is the link between diagnosis and classification?
- They are interlinked
- In the medical approach, to diagnose a specific disorder, you need to distinguish one from another
- This is done by identifying clusters of symptoms that occur together and classifying this as one disorder
- Diagnosis is then possible by identifying symptoms and deciding what disorder the person has
What are the two major systems for the classification of mental disorder?
- World Health Organisation’s ICD-10
- American Psychiatric Association’s Diagnostic and Statistical Manual DSM-5
How do the ICD-10 and DSM-5 differ in classifying schizophrenia?
They differ slightly in their classification of schizophrenia e.g. in the DSM system 1 positive symptom must be present whereas 2 or more negative symptoms are sufficient under ICD
How did previous editions of the ICD and DSM recognise subtypes of schizophrenia?
- They mainly involved powerful hallucinations and delusions
- Both systems dropped subtypes because they tended to be inconsistent
What are positive symptoms?
- Any additonal experiences beyong those of ordinary existence such as hallucinations and delusions
What are hallucinations?
- Unusual sensory experiences
- Some are related to events in the environment and some aren’t
- Hallucinations can be experienced in relation to any sense e.g. seeing distorted facial expressions
What are delusions?
- Also known as paranoia, they are irrational beliefs - Common delusions include being an important historical, political or religious figure
- They commonly involve being persecuted or having superpowers
- They can also concern the body and a person may believe they are under external control –> behave in ways that others would deem bizarre
What are negative symptoms?
- They involve the loss of usual abilities and experiences such as speech poverty and avolition
What is speech poverty?
- Characterised by changes in pattern of speech
- Deemed negative because there’s emphasis on the reduction in the amount and quality of speech produced –> can be accompanied by a delay in the person’s verbal responses during a conversation
- Speech disorganisation is when speech becomes incoherent or the speaker changes topic mid-sentence BUT this is seen as a POSITIVE symptom
What is avolition?
- Sometimes called apathy
- Can be described as finding it difficult to begin or keep up with goal-directed activity
- People with schizophrenia often have sharply reduced motivation to carry out a range of activities
- 3 signs include: poor hygiene/grooming + lack of persistence in work/education + lack of energy
In what ways does the diagnosis of schizophrenia have good reliability?
- Prior to DSM-5, reliability was low but has now improved - Osorio et al report excellent repeatability for diagnosis in 180 individuals using the DSM-5
- Pairs of interviewers reached inter-rater reliability of +9.7 and test-retest reliability of +9.2
In what ways does the diagnosis of schizophrenia have low validity?
- Cheniaux (2009) had 2 psychiatrists independently assess the same 100 clients using ISD and DSM criteria and found that 68 were diagnosed under the ICD system and 39 under DSM
- This suggests that schizophrenia is either over/under diagnosed, meaning criterion validity is low
In what ways does the diagnosis of schizophrenia have good validity?
- In the Osorio (2019) study, there was an excellent agreement between clinicians when they used 2 measures to diagnose schizophrenia both derived from the DSM system
- This suggests that the criterion validity for diagnosis is actually good, provided it takes place within a single diagnostic system
In what ways is the diagnosis of schizophrenia affected by co-morbidity?
- Schizophrenia is commonly diagnosed with other conditions
- Buckley et al’s review found that about half of those diagnosed with schizophrenia also had a diagnosis of depression or substance abuse
- This is a problem for classification because it means that schizophrenia may not exist as a distinct condition
In what ways is the diagnosis of schizophrenia affectd by gender bias?
- Since the 1980s, men have been diagnoses more commonly that women –> ratio of 1.4:1 (Fischer and Buchanan 2017)
- One possible explanation is that women are less vulnerable than men, perhaps due to genetic factors - HOWEVER it seems more likely that women are underdiagnoses because they have closer relationships and hence get more support (Cotton et al. 2009) - This means that women may not receive the treatment and services they might need
In what ways is the diagnosis of schizophrenia affected by culture bias?
- Some symptoms of schizophrenia e.g. hearing voices have different meanings in different cultures
- Black British people are up to 9x more likely to receive a diagnosis than white British people
- There seems to be an overinterpretation of symptoms in black British people –> suggesting discrimination from a culturally biased diagnostic system
In what ways does the diagnosis of schizophrenia suffers from symptom overlap?
- There is considerable overlap between the symptoms of schizophrenia and bipolar disorder
- This makes it hard to distinguish one from the other, leading to issues with classification and diagnosis
What is the “family studies” explanation for schizophrenia?
- They have confirmed that the risk of schizophrenia increases in line with genetic similarity
- Of course, family members tend to share environments as well as their genes, so the correlation represents both BUT family studies still give good support for the importance of genes in schizophrenia
What is the “candidate genes” explanation for schizophrenia?
- Early research looked for a single genetic variation, in the belief that one faulty gene could explain schizophrenia
- HOWEVER, it appears that a number of different genes are involved i.e. polygenic, most likely coding for neurotransmitters
What did the Ripke et al. (2014) study show in relation to candidate genes?
- It combined all previous data from genome-wide studies of schizophrenia
- The genetic makeup of 37,000 people with schizophrenia was compared to 113,000 controls.
- 108 separate genetic variations were associated with slightly increased risk of schizophrenia - It also appears that schizophrenia is aetiologically heterogeneous
What is the role of mutation in explaining schizophrenia?
- There could be mutations in parental DNA which can be caused by radiation, poison or viral infection
- Evidence for this comes from positive correlations between paternal age and risk of schizophrenia, increasing from around 0.7% with fathers under 25 to over 2% in fathers over 50 (Brown et al. 2002)
What is the original dopamine hypothesis?
- It was based on the discovery on the drugs used to treat schizophrenia (antipsychotics to increase DA) caused symptoms similar to those in people with Parkinson’s disease (linked to low DA levels)
- Therefore, schizophrenia may be the result of high dopamine levels (hyperdopaminergia) in subcortical areas of the brain
- For example, an excess of DA receptors in pathways from the subcortex to Broca’s area (speech production) may explain some symptoms such as speech poverty or hallucinations
What did Kenneth Davis et al. propose?
- The addition of cortical hypodopaminergia i.e. low dopamine levels in the brain’s cortex
- For example, low DA in the prefrontal cortex (linked to thinking) could explain the negative symptoms
- It has been suggested that cortical hypodopaminergia causes subcortical hyperdopaminergia