12.1.1

Classification & Diagnosis

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Classification and Diagnosis of Schizophrenia

Schizophrenia is a mental disorder. It is characterised by disruption in psychological functioning and loss of contact with reality.

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Schizophrenia in the population

  • Schizophrenia affects about 1% of the population.
  • Symptoms first show in mid to late adolescence.
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Psychological classification

  • There are currently two main classification systems for the diagnosis of mental disorders:
    • The International Classification of Diseases, Edition 10 (ICD-10), published by the World Health Organisation.
    • The Diagnostic and Statistical Manual (DSM-5), published by the American Psychiatric Association.
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Key features of classification systems

  • ICD-10 and DSM-5 classify schizophrenia slightly differently.
  • DSM-5 needs only one positive symptom (delusions, hallucinations) to be present for diagnosis.
  • ICD-10 needs two or more negative symptoms.
  • ICD-10 recognises sub-types of schizophrenia (paranoid schizophrenia, hebephrenic schizophrenia and catatonic schizophrenia).
    • These sub-types were omitted from the current edition of the DSM, even though they were present in previous editions.
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Types of schizophrenia

  • Paranoid schizophrenia is characterised by powerful delusions and hallucinations but relatively few other symptoms.
  • Hebephrenic schizophrenia involves mainly negative symptoms.
  • Catatonic schizophrenia involves disturbance to movement, leaving the sufferer immobile or overactive.

Positive and Negative Symptoms of Schizophrenia

People with schrizophrenia may experience many different symptoms.

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Positive symptoms of schizophrenia

  • Positive symptoms of schizophrenia are those that are not present in non-schizophrenic individuals and include hallucinations and delusions.
  • Hallucinations are unusual sensory experiences, such as hearing voices, that are not present in the environment. These voices can be very critical.
  • Hallucinations can also be visual, such as seeing people who aren’t there.
  • Delusions are irrational beliefs that can take many forms, such as believing you are a famous historical figure or under surveillance by the government.
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Negative symptoms of schizophrenia

  • Negative symptoms of schizophrenia involve the loss of usual abilities and experiences. Symptoms include avolition (or apathy) and speech poverty.
    • Avolition includes difficulties with goal-directed behaviour, such as personal hygiene, lack of persistence and lack of energy.
    • Speech poverty involves changes in the pattern of speech.
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Speech poverty interpretations

  • ICD-10 categorises speech poverty as a negative symptom because of the reduction in the amount and quality of speech, as well as a delay in verbal response during conversations.
  • DSM-5 places emphasis on speech disorganisation, rather than speech poverty. Speech can often become incoherent if the speaker changed topic mid-sentence.
  • DSM-5 classifies disorganised speech as a positive symptom.

Jump to other topics

1Social Influence

2Memory

3Attachment

4Psychopathology

5Approaches in Psychology

6Biopsychology

7Research Methods

8Issues & Debates in Psychology (A2 only)

9Option 1: Relationships (A2 only)

10Option 1: Gender (A2 only)

11Option 1: Cognition & Development (A2 only)

12Option 2: Schizophrenia (A2 only)

13Option 2: Eating Behaviour (A2 only)

14Option 2: Stress (A2 only)

15Option 3: Aggression (A2 only)

16Option 3: Forensic Psychology (A2 only)

17Option 3: Addiction (A2 only)

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