Diagnosis and classification

• Classification of mental disorders: The process of organizing symptoms into categories based on which symptoms frequently cluster together.
• Schizophrenia: A severe mental disorder where contact with reality and insight are impaired, an example of psychosis.
• Positive symptoms (definition): Atypical symptoms experienced in addition to normal experiences.
• Positive symptoms (examples): Hallucinations & Delusions.
• Hallucinations: Unusual sensory experiences. Some may be related to the environment and are distorted perceptions of what is there, others have no basis in reality and have no relationship to the senses. These include, hearing voices and seeing things that aren't there.
• Delusions: Irrational beliefs that have no basis in reality. This could cause people to act in ways that make sense to them but not other. A common example is the belief of them being persecuted by the government.
• Negative symptoms (definition): Atypical experiences that represent the loss of a usual experience.
• Negative symptoms (examples): Speech poverty & Avolition
• Speech poverty: Reduced frequency and quality of speech. Emphasis is put on speech disorganization, in which speech become incoherent mid-sentence.
• Avolition: Loss of motivation to carry out tasks, results in lowered activity levels.
• Andreasen (1982): Identified three signs of avolition- Poor hygiene, lack of persistence in work and lack of energy.
• Co-morbidity: The occurrence of two or more disorders together.
• Symptom overlap: Occurs when two or more conditions share symptoms.
• What are the two major systems that classify mental disorder?

  DSM-5 and ICD-10
• How does DSM-5 classify schizophrenia?


  One positive symptom must be present.
• How does ICD-10 classify schizophrenia?


  Two or more negative symptoms must be present.
• Evaluation of diagnosis (Strength):

  • Good reliability: Osorio et al reported excellent reliability for the diagnosis of schizophrenia in 180 individuals using DSM-5. We can be reasonably sure that the diagnosis of schizophrenia is consistently applied.
• Evaluation of diagnosis (Limitation):

  • Low validity: Cheniaux et al found that when the same 100 clients were diagnosed. 39 of them had schizophrenia when using DSM, and 68 had it when using ICD. This shows that the criterion validity is low.
• Evaluation of diagnosis (Limitation):

  • Co-morbidity: If conditions occur together a lot of the time, it questions the validity of their diagnosis. It may not exist as an actual condition.
• Evaluation of diagnosis (Limitation):

  • Gender bias: Men are more commonly diagnosed with schizophrenia, which could be due to women having closer relationships resulting in getting more support. This underdiagnoses means that women may not be therefore receiving the treatment that will benefit them.
• Evaluation of diagnosis (limitation):

  • Culture bias: Some symptoms, such as hearing voices, can mean different things for instance hearing ancestors.
  • This means people may be discriminated against by a culturally bias system.
• Evaluation of diagnosis (limitation):

  • Symptom overlap: There is a considerable amount of overlap in symptoms between schizophrenia and other conditions.
  • This means it may be hard to classify it as its own condition.