Classification

• Schizophrenia is a mental disorder affecting 1% of the population, with the onset of its first symptoms appearing at around 15-45 years of age. This is common in men, city-dwellers and low socio-economic groups.
• The diagnostic and statistical manual of mental disorders (DSM-5) is used by the APA and states that one positive symptom is sufficient for diagnosis.
• The international classification of disease (ICD-10) is also used by WHO and states 2 or more negative symptoms must be present for diagnosis.
• Positive symptoms are experiences that are in addition to normal experiences:

  • Hallucinations - Additional sensory experiences such as seeing distortions in objects that look like faces or hearing critical voices.
  • Delusions - Irrational beliefs about oneself or the world (eg - feelings of persecution).
• Negative symptoms are the loss of normal experience and abilities:

  • Avolition is the lack of purpose and willed behaviour. This results in no energy, sociability affection, or attempt at general hygiene. This is also known as apathy.
  • Speech poverty - Brief verbal communication style with a loss of quality and quantity of verbal responses.
• Co-morbidity is the presence of two or more disorders at the same time. Schizophrenia often tends to be diagnosed with bipolar disorder.
• Symptom overlap is when two or more symptoms are present at the same time. Bipolar disorder also has hallucinations and delusions as positive symptoms.
• Strengths of the classification of schizophrenia:

  • Diagnosis has good reliability - A reliable diagnosis is consistent between clinicians (inter-rater) and between occasions (test-retest). Osorio reported excellent reliability for schizophrenia diagnosis (DSM-5) with an inter-rater agreement of +.97 and test-retest reliability of +.92. This means that the diagnosis of schizophrenia is consistently applied.
• Limitations of the classification of schizophrenia:

  • Diagnosis has low validity - Criterion validity involves seeing whether different procedures used to assess the same individuals arrive at the same diagnosis. Cheniaux had two psychiatrists independently assess the same 100 clients. 68 were diagnosed with schizophrenia with ICD and 39 with DSM. This means that schizophrenia is either over or under diagnosed, suggesting that criterion validity is low.
• Limitations of the classification of schizophrenia:

  • Co-morbidity with other conditions - If conditions often co-occur then they might be a single condition. Schizophrenia is commonly diagnosed with other conditions. Buckley concluded that schizophrenia is co-morbid with depression (50% of cases), substance abuse (47%) or OCD (23%). This suggests that schizophrenia may not exist as a distinct condition.
• Limitations of classification of schizophrenia:

  • Gender bias - Men are diagnosed with schizophrenia more often than women, in a ratio of 1:4:1 (Fischer & Buchanan). This could be because men are more genetically vulnerable, or women have better social support, masking symptoms. This means that some women with schizophrenia are not diagnosed so miss out on helpful treatment.
• Limitations of the classification of schizophrenia:

  • Symptom overlap - There is overlap between the symptoms of schizophrenia and other conditions (eg - both schizophrenia and bipolar disorder involve delusions and avolition). Schizophrenia and bipolar disorder may be the same condition (a classification issue). Schizophrenia is hard to distinguish from bipolar disorder (a diagnosis issue). This means that schizophrenia may not exist as a condition and, if it does, it is hard to diagnose.