schizophrenia

• What is the prevalence of schizophrenia?

  Serious mental disorder affecting 1% of population. More common in males, city-dwellers and lower socioeconomic groups.
• What is the diagnostic progress of schizophrenia?

  Diagnosis and classification are interlinked. To diagnose a specific disorder, we need to be able to distinguish one disorder from another

  Classification — identify symptoms that go together = a disorder.

  Diagnosis — identify symptoms and use classification system to identify the disorder (e.g. depression, OCD, schizophrenia etc.).
• What is the ICD-10?

  ICD-IO (Vll published but not used for diagnosis until 2022) — two or more negative symptoms are suffcient for diagnosis (e.g. avolition and speech poverty).
• What is the DSM-5?

  DSM-5 — one positive symptom must be present (delusions, hallucinations or speech disorganisation).
• What are positive symptoms?


  Additional experiences beyond those of ordinary existence.
• What are the positive symptoms of schizophrenia?

  hallucinations

  delusions
• What are hallucinations? (positive symptoms)


  Unusual sensory experiences that have no basis in reality or distorted perceptions of real things. Experienced in relation to any sense. For example, hearing voices or seeing people who aren't there.
• What are delusions? (positive symptoms)


  Beliefs that have no basis in reality — make a person with schizophrenia behave in ways that make sense to them but are bizarre to others. For example, beliefs about being a very important person or the victim of a conspiracy.
• What are negative symptoms?


  Negative symptoms = loss of usual abilities and experiences.
• What are the negative symptoms of schizophrenia?

  speech poverty

  avolition
• What is Speech poverty? (negative symptom)

  A reduction in the amount and quality of speech. May include a delay in verbal responses during conversation. DSM emphasises speech disorganisation and incoherence as a positive symptom.
• What is Avolition? (negative symptom)


  Severe loss of motivation to carry out everyday tasks (e.g. work, hobbies, personal care). Results in lowered activity levels and unwillingness to carry out goal-directed behaviours.
• What is a strength of diagnosis of schizophrenia? (good reliability)

  P - one strength of diagnosis of schizophrenia is good reliability.

  E - A reliable diagnosis is consistent between clinicians (inter-rater) and between occasions (testretest)

  E - Osorio et al. (2019) report excellent reliability for schizophrenia diagnosis - inter rater agreement of +.97 and test-retest reliability of +.92.

  L - This means that the diagnosis of schizophrenia is consistently applied.
• What is a limitation of diagnosis of schizophrenia? (low validity)

  P - One limitation of diagnosis of schizophrenia is low validity.

  E - Criterion validity involves seeing whether different procedures used to assess the same individuals arrive at the same diagnosis.

  E - Cheniaux et al. (2009) had two psychiatrists independently assess the same 100 clients. 68 were diagnosed with schizophrenia with ICD and 39 with DSM.

  L - This means that schizophrenia is either over- or underdiagnosed, suggesting that criterion validity is low

  C - In the Osårio study (above) there was excellent agreement between clinicians using different procedures both derived from the DSM system. This means that the criterion validity for schizophrenia is good provided it takes place within a single diagnostic system
• What is a limitation of diagnosis of schizophrenia? (comorbidity)

  P - Another limitation is co-morbidity with other conditions.

  E - If conditions often cooccur then they might be a single condition. Schizophrenia is commonly diagnosed with other conditions

  E - For example Buckley et al. (2009) concluded that schizophrenia is comorbid with depression (50% of cases), substance abuse (47%) or CCD (23%).

  L - This suggests that schizophrenia may not exist as a distinct condition.
• What is a limitation of diagnosis of schizophrenia? (gender bias)


  P - A further limitation is gender bias.

  E - Men are diagnosed with schizophrenia more often than women, in a ratio of 1.4:1 (Fischer and Buchanan 2017).

  E - This could be because men are more genetically vulnerable, or women have better social support, masking symptoms.

  L - This means that some women with schizophrenia are not diagnosed so miss out on helpful treatment.
• What is a limitation of diagnosis of schizophrenia? (culture bias)


  P - A further limitation is culture bias.

  E - Some symptoms e.g. hearing voices, are accepted in some cultures, e.g. AfroCaribbean societies 'hear voices' from ancestors.

  E - Afro-Caribbean British men are up to ten times more likely to receive a diagnosis as white British men, probably due to overinterpretation of symptoms by UK psychiatrists

  L - This means that Afro-Caribbean men living in the UK appear to be discriminated against by a culturally-biased diagnostic system.
• What is a limitation of diagnosis of schizophrenia? (symptom overlap)


  P - A final limitation is symptom overlap.

  E - There is overlap between the symptoms of schizophrenia and other conditions e.g. both schizophrenia and bipolar disorder involve delusions and avolition.

  E - Schizophrenia and bipolar disorder may be the same condition (a classification issue). Schizophrenia is hard to distinguish from bipolar disorder (a diagnosis issue).

  L - This means that schizophrenia may not exist as a condition and, if it does, it is hard to diagnose.
• family studies - the genetic basis of schizophrenia


  Strong relationship between the degree of genetic similarity and shared risk of schizophrenia. Gottesman's (1991) large-scale study found someone with an aunt with schizophrenia has a 2% chance of developing it, 9% for a sibling and 48% for an identical twin. Family members also share environment but still indicates support for genetic view.
• candidate genes- the genetic basis of schizophrenia

  Early research looked unsuccessfully for a single genetic variation to explain schizophrenia. Schizophrenia is polygenetic - requires several genes. It is also aetiologically heterogeneous ie. risk is affected by different combinations.

  Ripke combined all previous data from genome-wide studies. Found 108 separate genes associated with slightly increased risk of schizophrenia
• mutation - the genetic basis of schizophrenia

  Schizophrenia can also have a genetic origin in the absence of a family history because of mutation in parental DNA.

  Evidence comes from the correlation between paternal age and risk of schizophrenia
• What is a strength of the genetic basis of schizophrenia?

  P - One strength is the strong evidence base.

  E - Family studies show risk increases with genetic similarity. Twin study found 33% concordance for MZ and 7% of DZ twins

  E - Adoption studies (e.g. Tienari et al. 2004) show that biological children of parents with schizophrenia are at greater risk even if they grow up in an adoptive family.

  L - This shows that some people are more vulnerable to schizophrenia because of their genes.
• What is a limitation of the genetic basis of schizophrenia?

  P - One limitation is evidence for environmental risk factors.

  E - Biological risk factors include birth complications (Morgan et al. 2017) and smoking THC-rich cannabis in teenage years (Di Forti et al)

  E - Psychological risk factors include childhood trauma e.g. 67% with schizophrenia (38% matched controls) reported at least one childhood trauma (Mørkved et al. 2017).

  L - This means genes alone cannot provide a complete explanation for schizophrenia.
• role of dopamine - neural correlates of schizophrenia


  dopamine is widely believed to be involved in schizophrenia because it is featured in the functioning of brain systems related to the symptoms of schizophrenia
• original DA hypothesis - neural correlates of schizophrenia


  high dopamine activity in subcortex associated with hallucinations and poverty of speech. may explain specific symptoms e.g poverty of speech
• updated hypothesis - neural correlates of schizophrenia

  updated hypothesis has added low levels of DA in the prefrontal cortex, could explain negative symptoms.

  Explains origins of abnormal DA - genetic variations and early experiences of stress make some people more sensitive to cortical hyperdopaminergia and hence subcortical hyperdopaminergia
• What is a limitation of the neural correlates of schizophrenia?

  P - One limitation is evidence for a central role for glutamate.

  E - Post-mortem and scanning studies found raised glutamate in people with schizophrenia : (McCutcheon et al. 2020).

  E -Also, several candidate genes for schizophrenia are believed to be involved in glutamate production or processing.

  L - This means that a strong case can be made for a role for other neurotransmitters in schizophrenia.
• What is a strength of the neural correlates of schizophrenia?

  P - One strength is support for dopamine in the symptoms of schizophrenia.

  E - Amphetamines (increase DA) mimic symptoms (Curran et al. 2004). Antipsychotic drugs (reduce DA) reduce intensity of symptoms (Tauscher et al. 2014).

  E -Candidate genes act on the production of DA or DA receptors

  L - This strongly suggests that dopamine is involved in the symptoms of schizophrenia.
• Family dysfunction - Schizophrenogenic mothers.

  Fromm-Reichmann's (1948) psychodynamic explanation of patients' early experiences of 'schizophrenogenic mothers' (mothers who cause schizophrenia). These mothers are cold, rejecting and controlling, and create a family climate of tension and secrecy. This leads to distrust and paranoid delusions and schizophrenia
• Family dysfunction - Double-bind theory.

  Bateson et al. (1972) described how a child may be regularly trapped in situations where they fear doing the wrong thing, but receive conflicting messages about what counts as wrong. They cannot express their feelings about the unfairness of the situation. When they 'get it wrong' (often) the child is punished by withdrawal of love — they learn the world is confusing and dangerous, leading to disorganised thinking and delusion
• Family dysfunction - Expressed emotion

  Expressed emotion (EE) is the level of emotion (mainly negative) expressed including: • Verbal criticism of the person with schizophrenia. • Hostility towards them. • Emotional over-involvement in their life. High levels of EE cause stress in the person, may trigger onset of schizophrenia or relapse.
• What is a strength of family dynsfunction?

  P - One strength is evidence linking family dysfunction to schizophrenia

  E - A review by Read et al. (2005) reported that adults with schizophrenia are disproportionately likely to have insecure attachment (Type C or D).

  E - Also, 69% of women and 59% of men with schizophrenia history of physical have and/or a sexual abuse.

  L - This strongly suggests that family dysfunction i does make people more vulnerable tvo schizophrenia,
• What is a limitation of family dysfunction?

  P - One limitation is the poor evidence base for any of the explanations

  E - There is almost no evidence to support the importance of traditional family-based theories

  E - Both theories are based on clinical observation of patients and informal assessment of the personality of the mothers of patients.

  L - This means that family explanations have not been able to explain the link between childhood trauma and schizophrenia.
• Cognitive explanations - Dysfunctional thought processing

  Lower levels of information processing in some areas of the brain suggest cognition is impaired. For example, reduced processing in the ventral striatum is associated with negative symptoms.
• Cognitive explanations - Metarepresentation leads to hallucinations.


  Metarepresentation is the cognitive thoughts and behaviour ability to reflect on (Frith et al. 1992). This dysfunction disrupts our ability to thoughts as our own — recognise our could lead to the hearing voices (hallucination) sensation of and experience of having thoughts placed in the mind by others
• Cognitive explanations - Central control dysfunction leads to speech poverty.


  Frith et al. (1992) also identified dysfunction of control as a way to explain speech central poverty - central control being the cognitive ability central to suppress automatic responses while performing deliberate automatic actions. People with schizophrenia experience derailment of thoughts because each word triggers automatic associations that they cannot suppress
• What is a strength of Cognitive explanations?

  P - One strength is evidence for dysfunctional thought processing.

  E - Stirling et 01. (2006) compared performance on a range of cognitive tasks (e.g. Stroop task) in people with and without schizophrenia.

  E - As predicted by centraL control theory, people with schizophrenia took over twice as long on average to name the font-colours.

  L - This supports the view that the cognitive processes of people with schizophrenia are impaired
• What is a limitation of Cognitive explanations?

  P - One limitation is only proximal origins of symptoms explained.

  E - Cognitive explanations for schizophrenia are proximal explanations — they explain what is happening now to produce symptoms

  E - Cognitive explanations are weaker as distal explanations (i.e. what causes cognitive problems), possible distal explanations are genetic and family dysfunction.

  L - This means that cognitive theories alone only provide partial explanations.
• Typical antipsychotics - dopamine antagonists


  - Typical antipsychotic drugs (e.g. chlorpromazine) have been around since the 1950s

  - They work by acting as antagonists in the dopamine system and aim to reduce the action of dopamine, they are strongly associated with the dopamine hypothesis
• Typical antipsychotics - block dopamine receptors in the synapses


  dopamine antagonists work by blocking dopamine receptors in the synapses in the brain, reducing the action of dopamine.

  Initially, dopamine levels built up after taking chlorpromazine, but then production is reduced. This normalises neurotransmission in key areas of the brain, which in turn reduces symptoms like hallucinations.