Schizophrenia OLD

• What is schizophrenia?

  • A psychotic disorder characterised by the loss of contact with reality
  • Experienced by around 1% of the world
  • More commonly diagnosed in men and those of lower socio-economic classes
• What are the DSM-5's requirements for diagnosis of schizophrenia?

  • 2 or more significant positive or negative symptoms present during a one month period
  • Must show social/occupational dysfunction like struggling with work or self-care
  • Continuous signs of disturbance must persist for 6 months and must not be accounted for by another disorder
• What are the ICD-10's requirements for diagnosis of schizophrenia?

  • Must have 2 significant symptom for a period of 1 month
  • 2 negative symptoms will suffice as opposed to the DSM-5's requirement for a positive symptom
  • Recognises sub-types of schizophrenia e.g. catatonic and paranoid schizophrenia
• What is reliability? What evidence supports good reliability in the diagnosis of schizophrenia?

  • Inter-rater reliability: when different diagnosing clinicians reach the same diagnosis for the same individual
  • Test-retest reliability: when the same clinician can reach the same diagnosis on two different occasions
  • Osorio et al: pairs of interviewers found to have +.97 inter-rater reliability and +.92 test-retest reliability when diagnosing schizophrenia in 180 individuals in 2019
  • Shows consistent application
• What is validity? What evidence shows low validity in the diagnosis of schizophrenia?

  • Criterion validity: whether different assessment systems arrive at the same diagnosis for the same patient
  • Cheniaux et al. (2009): 2 independent psychiatrists assessed the same 100 patients -> 1 psychiatrist - 44 were diagnosed under the ICD-10 but only 26 under the DSM-5
  • Shows that schizophrenia in general is either under or over diagnosed, with low criterion validity
• What is co morbidity? How is this a weakness of classification of schizophrenia?

  • Comorbidity: when two or more conditions co-occur questioning the validity of their diagnosis
  • Buckley et al: 50% of people diagnosed with schizophrenia also have depression, 47% also have substance abuse issues and 23% also have OCD
  • Means schizophrenia may not be a distinct condition and people may be wrongly diagnosed
• What is symptom overlap? How is this a weakness of the classification of schizophrenia?

  • Symptom overlap: when schizophrenia symptoms are also found in other conditions e.g. positive symptoms are found in BPD
  • Ellason & Ross: people with DID have more symptoms of schizophrenia than those diagnosed, sufficient enough to receive an entire other diagnosis
  • Shows classifications are not coherent enough to be associated distinctly to one disorder showing low accuracy and validity
• What examples are there of gender bias within the classification and diagnosis of schizophrenia?

  • Fischer & Buchanan: men are more commonly diagnosed w/ schizophrenia than women
  • Underdiagnoses women on the basis that they receive support from having closer relationships, therefore leading to them not receiving proper treatment
• What examples are there of culture bias within the classification and diagnosis of schizophrenia?

  • Pinto and Jones: African-Caribbeans in Britain are 9x more likely to be diagnosed with schizophrenia than white people in Britain but those living in African-Caribbean countries are not
  • Shows a culturally biased diagnostic system leading to discrimination against African-Caribbeans in Britain
• What are hallucinations as a positive symptom of schizophrenia?

  • Bizarre, unreal perceptions of the environment
  • Auditory: hearing voices/things others can't
  • Visual: seeing things others can't
  • Olfactory: smelling things others can't
  • Tactile: feeling things on skin/body others can't
• What are delusions as a positive symptom of schizophrenia?

  • Irrational beliefs about the environment that aren't real but seem real
  • Delusions of grandeur: inflated beliefs about an individual's power or importance
  • Delusions of reference: believing external events in the environment are directly related to them e.g. personal messages being communicated through TV or the radio
  • Common delusions involve being an important historical, political or religious figure like Jesus or Napoleon
• What is disorganised speech as a positive symptom of schizophrenia?

  • Individual has trouble organising their thoughts due to dysfunctional thought processes, which shows up in their speech
  • Derailment: slipping from one topic to another
  • 'Word salad': speech can be incoherent with a lack of fluency, sounding like a child's gibberish
• What is speech poverty a.k.a alogia as a negative symptom of schizophrenia?

  • Lessening of speech fluency, reflecting slow or blocked thoughts
  • May produce fewer words or only speak in response to others
• What is avolition as a negative symptom of schizophrenia?

  • A reduction of interests or desires for things and the inability to persist in goal-directed behaviour
  • Can manifest as a lack of emotional desire to initiate activities and can even involve sitting idly at home for hours doing nothing
• What is affective flattening as a negative symptom of schizophrenia?

  • Reduction in outward expression of emotions with less co-verbal behaviour
  • May speak in a dull, flat voice with no facial expressions
  • Deficit in prosody: less paralinguistic features like strength, tone or pitch of voice
• What is anhedonia as a negative symptom of schizophrenia?

  • Loss of interest/lack of reactivity to normally pleasurable stimuli
  • Physical anhedonia: no pleasure from physical stimuli like food or human contact
  • Social anhedonia: no pleasure from interpersonal interactions
  • Overall a less reliable symptom as it can overlap with other disorders like depression
• What are the differences between positive and negative symptoms of schizophrenia?

  • Positive symptoms tend to have greater weight during diagnosis but are harder to measure objectively and can be affected by cultural differences
  • Negative symptoms start a lot earlier (sometimes even years before positive ones), are much more objectively measured and are less affected by cultural differences
• What is the genetic explanation for schizophrenia?

  • Schizophrenia runs in families, allowing us to conclude that it has a genetic basis
• How do family and adoption studies support this explanation?

  • Gottesman (1991): someone with a schizophrenic identical twin has a 48% chance of developing it themselves, 9% for siblings, 2% for aunts
  • Shows positive correlation between genes and schizophrenia
  • Tienari et al (2000): 6.7% of 164 adoptees, whose biological mothers were schizophrenic, also received a diagnosis of schizophrenia compared to 2% of a control group
• What are candidate genes?

  • Candidate genes: put an individual at a higher risk of developing a disorder
  • Nucifora et al: found a link between mutations of the NSPA3 gene and schizophrenia
• What does it mean that schizophrenia is thought to be polygenic?

  • Polygenic: there are multiple genes that put an individual at higher risk
  • Ripke et al: combined data from genome wide studies and found 108 distinct genetic variations associated with the risk of sz
• What does it mean that schizophrenia is aetiologically heterogenous?

  • Different combinations of factors, including genetic variations, can lead to the condition and can have different origins
• What is the strong evidence base used to support the genetic explanation of schizophrenia?

  • Adoption studies like Tienari et al. eliminate confounding variables like the environment in the onset of schizophrenia
  • Hilker et al: found a concordance rate of 33% for monozygotic (identical) twins and 7% for dizygotic (non-identical) twins with schizophrenia
• How does ignoring environmental factors weaken the genetic explanation of schizophrenia?

  • Evidence shows that environmental factors can increase the risk of schizophrenia
  • Di Forti et al: smoking THC rich cannabis in teenage years can increase risk of schizophrenia development
  • Morkved et al: 68% of those with schizophrenia and related psychotic disorders experienced at least one childhood trauma as opposed to 35% of a control group w/ non psychotic issues
• How can genetic counselling be used to evaluate the genetic explanation of schizophrenia?

  • Informs potential parents of the probabilities of their child going on to develop schizophrenia by looking at their genes
  • Allows parents to prevent risky decisions in giving birth to children who would experience poor quality of life due to their disorder
  • BUT because of environmental, the risk factors cannot be exact and so aren't reliable for parents to base life-changing decisions on
• What is the neural correlates explanation of schizophrenia? How was the dopamine link discovered?

  • Focuses on importance of dopamine on areas of the brain that are influential in schizophrenia
  • Chlorpromazine, a calming sedative originally used for nausea and allergies, was found to effectively reduce schizophrenia symptoms after given to psychiatric patients
  • Taking chlorpromazine often caused similar symptoms to Parkinson's disease in patients, a disorder linked to low levels of dopamine
• What is the original dopamine hypothesis (hyperdopaminergia)?

  • Schizophrenia is the result of high levels of dopamine in the subcortical regions of the brain associated with positive symptoms
• What are the 2 sources of evidence that highlighted the original dopamine hypothesis?

  • Individuals exposed to amphetamine (dopamine agonist - increases dopaminergic activity) can develop characteristics of a schizophrenic episode, disappearing with abstinence from the drug
  • Antipsychotic drugs (dopamine antagonist - decreases dopaminergic activity) block the activity of DA in the brain and eliminate symptoms like hallucinations and delusions, strengthening the role of DA in schizophrenia
• What is the updated dopamine hypothesis (hypodopaminergia)?

  • Schizophrenia is the result of low levels of dopamine in cortical regions (prefrontal cortex) of the brain, presenting as negative symptoms
  • Davis et al. (1991): negative symptoms of sz are thought to arise from a deficit of DA in the mesocortical pathway, caused by excess DS in subcortical areas like the mesolimbic pathway
• What causes hyper and hypodopaminergia?

  • Howes (2017): genetic variations combined with physical and environmental stressors leads to greater sensitivity to these two levels of dopamine in the brain
• How is white matter involved in schizophrenia?

  • White matter: made up of nerve fibres covered in myelin, an insulating sheath that helps to conduct information quickly through the CNS for efficient processing
  • Du et al. (2013): found reduced myelination of white matter pathways in schizophrenic patient, showing possible impairment of information processing
• What research support is there for the original dopamine hypothesis?

  • Leucht et al. (2013): meta-analysis of 212 studies concluding that antipsychotics (dopamine antagonists) are more effective in symptom reduction than placebos
  • Displays the link between schizophrenia and dopamine, supporting the idea of hyperdopaminergia
• What research support is there for the updated dopamine hypothesis?

  • Patel et al. (2010): analysed PET scans and found lower levels of dopamine in the prefrontal cortexes of schizophrenia patients as opposed to neurotypical controls
  • Supports the idea of hyperdopaminergia
• What evidence is there against the role of dopamine in schizophrenia?

  • Noll (2009): antipsychotics don't alleviate symptoms in about 1/3rd of people
  • People with regular dopamine levels still experience positive symptoms like hallucinations and delusions, making the explanation questionable as the dopamina-schizophrenia link is not universal in all patients
• What evidence is there for other important neurotransmitters and how does this weaken the neural correlates explanation?

  • McCutcheon et al (2020): post mortems + live scanning studies found raised levels of glutamate in certain brain regions of schizophrenic patients
  • Several candidate genes are believed to be involved in glutamate production
  • Shows equally strong cases can be made for other neurotransmitters that aren't dopamine, questioning the exclusivity of dopamine-schizophrenia link
• What are typical antipsychotic drugs as a biological treatment for schizophrenia? (1950s)

  • Dopamine antagonists - block dopamine receptors and have a sedative effect on patients
  • Bind to but do not stimulate dopamine receptors, blocking their action and normalising neurotransmission in key areas of the brain, reducing positive symptoms
  • Chlorpromazine - often used to calm anxious patients admitted to the hospital
• What are some side effects of typical antipsychotics like chlorpromazine?

  • Sedative effect
  • Extrapyramidal side effects in patients with Parkinson's disease rapid sudden movement that are involuntary
• What are atypical antipsychotics? (1970s)

  • Still block D2 receptors but only temporarily occupy them, before rapidly dissociating to allow normal dopamine transmission
• How are atypical antipsychotics different to typical ones?

  • Tend not to affect the dopamine systems that control movement, carrying a lower risk of extrapyramidal side effects
  • Also benefit negative symptoms as well as cognitive impairment by affecting a wider range of neurotransmitter systems
  • Can be administered through injection, suitable for treatment-resistant patients
  • Block D2 receptors for a short period, typical block them longer
  • Stronger affinity for serotonin receptors, lower for dopamine
• What is clozapine as an atypical antipsychotic?

  • Binds to dopamine receptors and also acts on serotonin and glutamate receptors, helping improve mood and reduce anxiety
  • Can be fatal for people with a blood condition called agranulocytosis, so regular blood tests are taken to ensure patients do not have this condition
  • More effective than atypical antipsychotics