Classification and diagnosis

• Schizophrenia


  A severe mental disorder, characterised by profound disruptions in thinking. This can affect language, perception, emotions and sense of self.
• How does the medical approach diagnose a disorder?

  • In order to diagnose a specific disorder, we need to distinguish one disorder from another.
  • We do this by identifying a cluster of symptoms that occur together and classifying this as one disorder.
  • Diagnosis is then possible by identifying symptoms and deciding what disorder a person has.
• What are the 2 major systems used for classification and diagnosis?

  • ICD-10: 2 or more negative symptoms must be present
  • DSM-5: 1 positive symptom must be present
• Why have both classification systems dropped subtypes of schizophrenia?

  • They tended to be inconsistent. E.g someone would have a diagnosis of paranoid schizophrenia and would not necessarily show the same symptoms a few years later.
• Positive symptoms


  Atypical symptoms experienced in addition to normal experiences.

  • Highly exaggerated ideas, perceptions or actions that show the person can’t tell what’s real from what isn’t.
• Negative symptoms


  Atypical experiences that represent the loss of usual experiences.

  • Refer to an absence or lack of Normal mental functioning involving thinking, behaviour and perception.
• Positive symptoms

  • Hallucinations
  • Delusions
• Negative symptoms

  • Avolition
  • Speech poverty
• Hallucinations

  • Unusual sensory experiences.
  • Some hallucinations are related to the environment whilst others are not.
  • E.g voices are heard either talking to or commenting on the sufferer, often criticising them.
  • Hallucinations can be experienced in relation to any sense.
  • E.g see distorted facial expressions or occasionally people/animals that are not there.
• Delusions

  • Irrational beliefs that can take many forms.
  • Common delusions involve being an important historical, political or religious figure.
  • Delusions often commonly involve being persecuted, perhaps by government or aliens or of having superpowers.
  • Another class involves the body being controlled.
  • Delusions can make a sufferer of schizophrenia behave it ways which make sense to them but seem bizarre to others.
• Avolition

  • Finding it difficult to begin or keep up with goal directed activity.
  • Severe loss of motivation to carry out everyday asks.
• Speech poverty- ICD

  • Changes in patterns of speech.
  • ICD-10 recognised speech poverty as a negative symptoms due to the reduction in the amount and quality of speech.
  • Accompanied by a delay in verbal responses during conversation.
• Speech poverty- DSM-5

  • Places its emphasis on speech disorganisation in which speech becomes incoherent or the speaker changes topic mid-sentence.
  • Speech disorganisation is classified in DSM-5 as a positive symptom of schizophrenia.
• Co-morbidity

  • The occurrence of 2 illnesses or conditions together.
  • E.g a person having both schizophrenia and personality disorder.
  • Where 2 conditions are frequently diagnosed together, it questions the validity of classifying the 2 disorders seperately.
• Why is co-morbidity a limitation of classification and diagnosis?

  • Buckley et al found that about half of those diagnosed with schizophrenia also had a diagnosis of depression or substance abuse.
  • If conditions occur together, this this calls into question the validity of the diagnosis and classification because it may be a single condition.
  • SZ may not exist as a distinct condition which is a problem for diagnosis as some people diagnosed with SZ are also diagnosed with depression.
• Symptom overlap

  • Occurs when 2 or more conditions share symptoms.
  • Where conditions share many symptoms this calls into question the validity of classifying the 2 disorders separately.
• Why is symptom overlap a limitation of classification and diagnosis?

  • There is considerable overlap between symptoms of SZ and symptoms of other conditions. E.g both SZ and bipolar disorder involve positive symptoms such as delusions and negative symptoms such as avolition.
  • This suggests that SZ and bipolar disorder may not be 2 different conditions but variations of a single condition.
  • In terms of diagnosis, it means that SZ is hard to distinguish from bipolar disorder and could lead to unreliable or incorrect diagnosis.
• Explain why the classification and diagnosis of SZ has low validity?

  • Cheniaux et al, has 2 psychiatrists independently assess 100 clients using ICD-10 and DSM-5. Found that 68 were diagnosed with SZ under ICD, and 39 under DSM.
  • This suggests that SZ is more likely to be diagnosed using the ICD in comparison to DSM.
  • In terms of diagnosis, SZ is either over-diagnosed or under-diagnosed depending on the diagnostic system.
• How does the classification and diagnosis of SZ have high reliability?

  • A psychiatric diagnosis is considered reliable when different diagnosing clinicians reach the same diagnosis for the same individual (inter-observer reliability), and when the same clinician reaches the same diagnosis for the same individual on 2 occasions (test-retest reliability).
  • Osorio et al, reported the reliability as high we diagnosing 180 individuals using DSM. Pairs of interviewers achieved inter-rater reliability of +.97 and test-retest reliability of +.92.
  • Confident that the diagnosis consistently applied.
• Why does the classification and diagnosis of a have cultural bias?

  • Some symptoms of SZ e.g hearing voices have different meanings in different cultures. E.g in Haiti some people believe that voices are communications from ancestors.
  • British people of African-Caribbean origin are 9 times more likely to receive a diagnosis compared to white British people (Pinto and Jones), people living in Afro-Caribbean countries are not.
  • Over interpretation of symptoms in British Afro-Caribbean people, which they may be discriminated against using a culturally biased diagnostic system/