quizlet

• What is schizophrenia?


  > A severe mental disorder where contact with reality and insight is impaired.

  > About 1% of the world's population has it
• What are the 2 major systems for classification of mental disorder?

  > DSM-5(Diagnostic statistical manual)

  > ICD-10(World Health organisation's International classification of Disease)
• What has to be present in the DSM-5 for a diagnosis of schizophrenia?

  > Positive Symptoms

  > This is the opposite under the ICD
• Why have the 2 dropped subtypes?

  > Tended to be inconsistent as someone with a diagnosis of paranoid schizophrenia may not necessarily show those symptoms years later.
• What are the positve symptoms of schizophrenia?

  > Additional experiences beyond ordinary existence

  > They include: hallucinations + delusions
• What are hallucinations?


  > Sensory experiences that have no basis in reality

  > e.g. voices heard often criticising a person.

  > A person may also see distorted facial expressions or people that are not there.
• What are delusions?


  > Beliefs that have no basis in reality

  > e.g. a person may believe that they are an important historical figure like Jesus

  > A person may also believe that they are under external control

  > These delusions make sense to the person but not anyone else.
• What are negative symptoms of schizophrenia?

  > Involves the loss of usual abilities and experiences

  > Include: speech poverty + avolition
• What is speech poverty?

  > Reduction in the amount and quality of speech

  > Nowadays there is more focus on speech disorganisation where speech becomes incoherent or the speaker changes topic mid-sentence (classified in the DSM as a positive symptom)
• What is avolition?


  > Lack of motivation = lowered activity levels

  > Andreasan defined 3 signs of this: poor hygiene, lack of persistence in work + lack of energy
• Co-morbidity(Limitation)


  >If conditions occur together than it calls into question the validity of their diagnosis as it may just be 1 condition

  > A review found that half of those diagnosed with schizophrenia was also diagnosed with depression/substance abuse.

  > This is a problem for classification as it means that schizophrenia may not exist as its own distinct condition.
• Gender bias in diagnosis (limitation)

  > Since the 1980s, men have been diagnosed with schizophrenia more than women (a ratio of 1.4:1, Fischer et al)

  > An explanation of this is that women may be less vulnerable due to genetic factors

  > It seems more likely that women are underdiagnosed as they have close relationships and get support = women with schizophrenia functioning better than men.

  > An underdiagnosis in women may mean that they are not getting adequate treatment that could be benefitting them.
• Culture bias (limitation)


  > Some symptoms like hearing voices have different meanings in different cultures - people in Haiti believe that voices are their ancestors communication with them.

  > British people of African-Caribbean descent are 9x more likely to receive a diagnosis than white British people(Pinto)
• Symptom overlap (Limitation)


  > There is considerable overlap in the symptoms of schizophrenia and other conditions - i.e. schizophrenia + bipolar both involve positive symptoms + negative symptoms.

  > This may suggest that the 2 conditions are variations of a single condition

  > In terms of diagnosis it means that schizophrenia is hard to distinguish from bipolar disorder.
• Good reliability (strength)


  > Reliability = consistency

  > A diagnosis is said to be reliable when different clinicians reach the same diagnosis for the dame person (inter-rater reliability) + when the same clinician reaches the same diagnosis twice (test-retest reliability)

  > Osorio et al. has reported excellent reliability for the diagnosis of schizophrenia in 180 people using the DSM-5.

  > We can therefore be confident that the diagnosis of schizophrenia is consistently applied.
• Low validity (Limitation)


  > Cheniaux et al. had 2 psychiatrics independently assess the same 10 patients using DSM- 4 and ICD-10 and found that 68 were diagnosed with schizophrenia under the ICD system and 39 under DSM.

  > Suggests that schizophrenia is either under/over diagnosed = low criterion validity
• However...


  > In Osorio's study, there was excellent agreement between clinicians when they used to measures to diagnose schizophrenia both from the DSM system.

  > It suggests that criterion validity is good provided it takes place within a singular diagnostic system.
• What are the biological explanations for schizophrenia?

  > Genetic basis

  > Neural correlates.
• What are the role of family studies in schizophrenia?

  > Confirm the risk of schizophrenia increases in line with genetic similarity to a relative with the disorder.

  > Gottesman's large scale family study shows this.

  > Aunt with schizophrenia = 2% chance of developing it.

  > Grandchildren = 5%

  > Sibling = 9%

  > Identical twin = 48%
• Schizophrenia is...


  > Polygenic

  > Ripke et al. combined all previous studies from genome-wide studies of schizophrenia. The genetic make-up of 37,000 people with a diagnosis of schizophrenia was compared to 113,000 controls.

  > 108 separate genetic variations were associated with a slight increased risk of gaining schizophrenia.

  > Also appears that schizophrenia is aetiologically heterogeneous.
• What role does mutation play in developing schizophrenia?

  > Mutation in parental DNA which can be caused by radiation, poison or viral infection. This can lead to development of schizophrenia in the offspring.
• Research support (Strength)


  > Family studies like Gottesman show that risk increase with genetic similarity.

  > Adoption studies such as Tienari et al. show that biological children of parents with schizophrenia are at heightened risk even if they grow up in an adoptive family.

  > This shows that some people are more vulnerable to schizophrenia due to their genetic make-up.
• Environmental factors (limitation)


  > There is clear evidence to also suggest that environmental factors also increase the risk of developing schizophrenia.

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

  > Psychological risk factors = childhood trauma which leaves people more vulnerable to adult mental health problems in general.

  > Morkved et al. found 67% of people with schizophrenia and related psychotic disorders reported at least one childhood trauma as opposed to 38% of a matched control group.

  > This means that genetic factors alone cannot provide a complete explanation for schizophrenia.
• What is the best known neural correlate of schizophrenia?

  > Dopamine (DA)
• What is the original dopamine hypothesis?

  > Based on the discovery that antipsychotics (which reduce DA), caused similar to symptoms in those who had Parkinson's disease, a condition associated with low DA levels.

  > Therefore schizophrenia may be the result of high DA levels in subcortical areas of the brain.

  > e.g. an excess of DA receptors in pathways from the subcortex to Broca's area may explain specific symptoms of schizophrenia such as poverty of speech.
• What are the updated versions of the dopamine hypothesis?

  > Davis et al. proposed the addition of cortical hypodopaminergia (abnormally low DA in the brain's cortex)

  > This can explain symptoms of schizophrenia like low DA in the prefrontal cortex, which is responsible for thinking, could explain cognitive problems.

  > Also been suggested that cortical hypodopaminergia can lead to subcortical hyperdopaminergia.

  > It seems that genetic variations and early experiences of stress can make some people more vulnerable to cortical hypodopaminergia and hence subcortical hyperdopamiergia (Howes et al.)
• Evidence for dopamine (strength)

  > Amphetamines increase DA and worsen symptoms in people with schizophrenia and induce symptoms in people without (Curran et al.)

  > Antipsychotic drugs reduce DA activity and also reduce the intensity of symptoms (Tauscher et al)

  > Some candidate genes act on the production of DA or DA receptors.

  > Suggests that dopamine is involved in the symptoms of schizophrenia.
• Glutamate (Limitation)


  > One limitation of the dopamine hypothesis is evidence for a central role of glutamate.

  > Post-mortem and live scanning studies have consistently found raised levels of the neurotransmitter glutamate in several brain regions of people with schizophrenia (McCutcheon et al.) In addition, several candidate genes for schizophrenia are believed to be involved in glutamate production/processing.

  > This means that an equally strong case can be made for other neurotransmitters other than dopamine.
• What is the most common drug therapy for schizophrenia?

  > Antipsychotics

  > 'Psychosis' refers to the loss of contact with reality - delusions/hallucinations.

  > Could be used in the short term/long term.
• What are the 2 types of antipsychotics?

  > Typical

  > Atypical (newer)
• What are the typical antipsychotics?

  > Used since 1950s.

  > Includes Chlorpromazine, can be taken as tablets syrup injection

  > Daily oral dosage = 1000mg

  > Typical prescribed doses have declined over the last 50 years.
• How do typical antipsychotics work?

  > Act as antagonists in dopamine system.

  > Antagonists reduce the action of neurotransmitters - these block dopamine receptors in the synapses of the brain, reducing action.

  > According to the hypothesis, this will allow the reduction of positive symptoms such as hallucinations.
• What other effect does chlorpromazine have?

  > A sedative effect.

  > Often used to calm individuals with schizophrenia.

  > Syrup is absorbed faster than tablets so is often used when it acts as a sedative.
• What are the atypical antipsychotics?


  > Used since 1970s.

  > Aim to improve effectiveness of drug in suppressing symptoms as well as reducing side effects.
• What are 2 atypical antipsychotics?

  > Clozapine - typical dosage is 300 - 450mg, only used when other treatments fail due to possible development of agranulocytosis (blood condition), more effective then typical.

  > Risperidone - developed to have less side effects and be just as effective, can be taken in different forms, tablets, syrup, injection, daily dosage 4-8mg.
• How do these atypical antipsychotics work?

  > Clozapine binds to dopamine receptors, acts on serotonin + glutamate receptors.

  > Improves mood and reduces depression in patients.

  > That is why this drug is prescribed when patient is at high risk of suicide

  > Risperidone binds more strongly to dopamine receptors and therefore is effective in smaller doses = fewer side effects.
• Evidence for effectiveness


  > Thornley et al.

  > reviewed studies comparing chlorpromazine to control conditions.

  > Data from 13 trials with over 1000 participants reveal that chlorpromazine was associated with better functioning and reduction in symptoms.

  > Meltzer did a review and found that clozapine is more effective than typical antipsychotics and other atypical antipsychotics.
• However...


  > Healy suggested serious flaws with evidence for effectiveness.

  > Most studies are of short term effects only + successful trials results are published numerous times to exaggerate the size of the evidence bade.

  > Because antipsychotics have powerful calming effects, it is easy to demonstrate that they have a positive effect, this is not the same as saying they reduce the severity of psychosis.

  > Evidence base less impressive than first seems.
• Serious Side effects


  > Typical antipsychotics = dizziness, sleepiness, weight gain.

  > Long term use can cause tardive dyskinesia causes involuntary facial movements.

  > Neuroleptic malignant Syndrome (NMS) - can be fatal, most serious side effect.
• Mechanism unclear


  > We do not know WHY antipsychotics work.

  > We know that original dopamine hypothesis is not a complete explanation for schizophrenia, and dopamine levels in other areas in the brain are too low, this means that most antipsychotics should not work.