Schizophrenia

Diagnosis

Schizophrenia is a complex disorder and has diverse clinical presentations. Criterion-based systems, including the ICD-10 and DSM-IV, describe the characteristic symptoms of schizophrenia to aid diagnosis. According to ICD-10, severe symptoms should be present for a month, whereas with DSM-IV, the severe symptoms must be present for 6 months. Common behavioural symptoms of schizophrenia (or schizophrenic disorders) are:

• psychotic (delusions, hallucinations)
• disorganised thinking or speech
• negative symptoms (see below)
• catatonia.

People with schizophrenia often show premorbid manifestations of the disease in their teenage years. These include mild social symptoms and low academic achievement, effects on the individual's language, thought, perception and sense of who they are. The symptoms are often unrecognisable as the first signs of schizophrenia at this stage, but may worsen over time to include psychotic manifestations such as hearing voices or seeing things (hallucinating). Once the disease has developed to the point of the first psychotic episode, several further symptoms are associated with the disease. These are classified as being either positive or negative symptoms.

The most common types of schizophrenic disorders and their associated symptoms (classified according to ICD-10 criteria and diagnosed according to predominant symptoms shown by the individual at the time of evaluation) are:

• Paranoid schizophrenia
  the most common type of schizophrenia. The individual is relatively stable, often paranoid and has delusional symptoms, such as persecution and thought control by outside forces, as well as hallucinations of various types. The course of paranoid schizophrenia may be episodic or chronic.

• Hebephrenic schizophrenia
  the individual may show primarily negative symptoms - prominent affective changes, transient hallucinations, disorganised speech and thought, irresponsible and unpredictable behaviour (giggling and playing pranks). This type of schizophrenia includes disorganised schizophrenia.

• Catatonic schizophrenia
  the individual shows primarily psychomotor disturbances, which may alternate between extremes such as hyperkinesis and stupor. Constrained attitudes and postures may be maintained for long periods of time and episodes of violence may be a striking feature of this form of schizophrenia.

All three types may overlap with each other to varying degrees. Other, more uncommon, minor variations of schizophrenic disorders include undifferentiated schizophrenia, post-schizophrenic depression, residual schizophrenia and simple schizophrenia.

Factsheet: Diagnosis of mental disorders

Factsheet: Rating scales