Schizophrenia

• what is schizophrenia 


  SZ can be characterised as a lack of contact with reality. A person with schizophrenia has a breakdown of communication between different parts of the brain. For diagnosis patients must show several different types of abnormal behaviour and symptoms can either be positive or negative.
• positive symptoms of schizophrenia

  • hallucinations
  • delusions
  • auditory
• negative symptoms of sz

  • speech poverty
  • avolition
• what are the diagnostic manuals used in sz

  • ICD
  • DSM
• what is DSM

  patients must have one positive symptom present
• What is ICD


  Patients must have two or more negative symptoms
• what is reliability of diagnosis 


  It is the extent to which psychiatrists can agree on the same diagnosis when independently assessing patients.
• issue with reliability - cheniaux et al 


  Cheniaux et al (2009) found that inter rater reliability between two psychiatrists was low. For instance, one psychiatrist diagnosed 26/100 patients with sz using the DSM and 44/100 using the ICD. The other psychiatrist diagnosed 13/100 using the DSM and 24/100 using the ICD. This demonstrates a low inter-rater reliability between the two psychiatrists which shows that sz is either over diagnosed in the ICD and under diagnosed in the DSM.
• soderberg et al 


  Reported a concordance rate of 81% using the DSM classification system. The DSM classification system is regarded as more reliable than the ICD because the symptoms outlined for each category are more specific.
• Nilsson et al


  Found only a 60% concordance rate between practitioners using the icd classification system which implies that the dsm classification system is more reliable.
• what is comorbidity 


  This is when two conditions co-exist within the same individual at the same time. Someone who suffers from sz may also be suffering from another condition.
• Comorbidity - Buckley (2009)


  When looking at comorbidity in sz patients it was found that 50% also had depression, 47% substance abuse,29% PTSD and 23% OCD. It may be that sz looks a lot like depression and vice versa. This raises the issue of descriptive validity because having simultaneous disorders suggests that sz might not actually be a separate disorder.
• What is symptom overlap 


  This occurs when two or more conditions share the same symptoms.

  E.g sz and bipolar disorder both share positive symptoms such as delusions and negative symptoms like avolition. This lack of distinction calls into question the validity of the classification and diagnosis of sz. Shared symptoms could lead to an unreliable/incorrect diagnosis because the person may exhibit a symptom typical of schizophrenia (eg delusions) but could instead have another condition with the same symptom (eg bipolar disorder).
• Ellason and Ross 


  found that people with dissociative identity disorder (DID) actually have more schizophrenic symptoms than people diagnosed with sz.
• Ketter (2005)


  Looked into issues with co-morbidity and symptom overlap and found that misdiagnosis could lead to years of delay in receiving the relevant treatment. During this time suffering and further degeneration can occur therefore resulting high levels of suicide.
• cultural issues with reliability of diagnosis - copeland

  There are issues with reliability of diagnosis of sz across cultures. Copeland gave a description of a patient to UK and US clinicians finding that 69% of the US clinicians diagnosed the patient with sz while only 21% of uk clinicians diagnosed the patient with sz. This calls into question the reliability of diagnosis across different cultures because patients who show the same symptoms recieve different diagnosis because of the different ethnic backgrounds of the clinicians.
• cultural bias in diagnosis

  African American and english people with caribbean origin are several times more likely to be diagnosed with sz than white people this is because there are cultural differences. For instance, someone may be experiencing positive symptoms of sz such as hallucinations and hearing voices and would therefore be diagnosed with sz in one culture but in certain African cultures this is perfectly understandable because they believe to have contact with their ancestors.
• pinto et al 


  Compared British and Jamaican psychiatrists where British psychiatrists diagnosed 62% of black caribbean patients with sz while jamaican psychiatrists diagnosed 55% of patients with sz. This shows that although a similar proportion of patients were classified as suffering from schizophrenia, agreement about the diagnosis of schizophrenia in black patients was only reached in 55% of cases. This incorporation of some ethnic and cultural information doesn't matter because race continues to be an issue. Diagnosis is incomplete without an understanding of cross cultural variance.
• gender bias - Loring and powell 


  Randomly selected 290 male and female psychiatrists to read two case articles and make a judgement on their behaviour based on the diagnostic criteria. They found that when patients were described as male 56% were diagnosed with sz compared to 20% if they were described as female. This gender bias didn't occur amongst female psychiatrists suggesting that diagnosis is influenced by the gender of the patient and the psychiatrist.
• Biological explanations for sz

  • Genetics
  • dopamine hypothesis
  • neural correlates
• Genetic explanation for sz

  Suggests that sz is inherited through genes from biological parents.

  Gottesman et al studied 40 twins and found a concordance rate of mz twins to be 48% but only 17% for dz twins. This suggests that mz twins are more likely to suffer from sz than dz twins. this therefore supports a genetic explanation for the development of sz because mz twins are more genetically similar than dz twins.
• limitation of gottesman et al - ignores other factors 


  The concordance rate for mz twins was not 100% which it would be if sz was entirely determined by genetics. This suggests that there are other factors influencing the development of sz such as the environment. For instance, the concordance rate of siblings was 9% while it was 17% for dz twins. This supports the influence of the environment on developing sz because siblings and dz twins have the same genetic similarity but would be exposed to different environments.
• what is hypodopaminergia 


  low levels of dopamine in the D1 receptors at the prefrontal cortex causing negative symptoms of sz such as avolition and speech poverty.
• what is hyperdopaminergia 


  high levels of dopamine at the D2 receptors in the subcortex causing positive symptoms of sz such as hallucinations and delusions.
• strength of dopamine hypothesis - practical applications 


  One strength of the dopamine hypothesis is that it has practical applications. For example, it has led to the development of antipsychotics which is a biological treatment for sz that block the receptors and act as a dopamine antagonist. This helps to treat sz and is associated with better overall functioning and reduced symptom severity.
• limitation of dopamine hypothesis - mixed evidence

  Curran et al suggested that amphetamines which are dopamine antagonists increase levels of dopamine and can produce schizophrenic-like symptoms in non sufferers. While on the other hand there is research to suggest that antipsychotic drugs can reduce dopamine activity. However it could be that dopamine doesn't provide a complete explanation for sz because some of the genes in ripke's study also code for other NT's such as glutamine. This could mean that several neurotransmitters may be involved in the development of sz.
• limitation of dopamine hypothesis - issue of cause and effect

  One limitation of the dopamine hypothesis is that there is an issue with cause and effect. For instance, it is uncertain whether a dopamine imbalance causes sz or whether sz causes a dopamine imbalance.
• neural correlates 


  suggests that structures of the brain are associated with positive or negative symptoms of sz.
• Juckel (2006)


  they measured activity levels in the striatum and found lower levels in sz patients compared to the control group and a negative correlation between activity levels and severity of symptoms.
• Allen et al 


  measured activity levels in the superior temporal gyrus and anterior cingulate gyrus and found that reduced activity in these areas of the brain was a neural correlate for auditory hallucinations.
• limitation of neural correlates - relies on correlational research


  objective research and several studies found similar patterns but a correlation does not show causation. It may be that negative symptoms in Juckel's research could be due to inactivity or negative symptoms causing less information to pass through the striatum. it can be argued that neural correlates tell us very little about the onset of sz.
• Limitation of biological explanations - biological reductionist


  This is because it simplifies a complex disorder like sz down to simple biological components such as genetics, neural correlates and dopamine levels. It may be more appropriate to use an interactionist approach to explaining sz using the diathesis stress model. This suggests that someone can be genetically predisposed to a disorder such as sz but it is triggered by a stressor in the environment.
• interactionist approach may be more appropriate to biological


  This could be supported by sorvi et al who found in a study of finish adoptees , children were more likely to develop sz if they were reared in a non healthy environment. This highlights the importance of the environment in the development of sz because these children may have been genetically predisposed to sz but this was only triggered after being brought up in an unhealthy environment.
• what are the biological treatments for sz

  • Typical antipsychotics
  • Atypical antipsychotics
• What are typical antipsychotics

  They work as dopamine antagonists blocking the D2 receptors on postsynaptic neurons. Can be seen to reduce positive symptoms of sz by normalising dopamine transmission

  E.g chlorpromazine
• evidence for the effectiveness - Typical antipsychotics

  Thornley took data from 13 trials with over 1121 patients(under strict controlled conditions) and found the drug to be associated with better overall functioning and reduced symptom severity.
• what are atypical antipsychotics

  Binds to the same receptors as typical antipsychotics but also act on glutamine and serotonin. Improves mood, reduces depression and anxiety in patients. The mood enhancing properties mean that it is prescribed when patients are at high risk of commiting suicide.
• evidence for effectiveness - atypical antipsychotics

  Meltzer reviewed clozapine vs typical AP's and found that they were more effective than other AP's. Atypical AP's were more effective in 30-50% of treatment resistant cases where typical AP's had failed.
• strength of drug treatments - alleviates symptoms quickly 


  One strength of drug treatments is that it alleviates symptoms quickly which allows patients to get back to normal life and leave institutional care. this allows them to live a better quality life where they can live independently within society again.
• limitation of drug treatments - may not be effective in long term 


  One limitation of drug treatments is that few studies look at the effectiveness of AP's in the long term. So it might be that AP's are not a long term solution because we don't know how exactly it affects you in the long run.