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Symptoms and Definition of Schizophrenia

Core Symptoms of Schizophrenia

According to the DSM-IV-TR, to be diagnosed with Schizophrenia a person must have two or more of the following core symptoms for a period of one month (or less than one month if the person has received effective treatments):

  • Delusions
  • Hallucinations
  • Speaking in a way that is disorganized, incoherent or bizarre, to the point where the person is unable to communicate effectively with others
  • Behaving in a way that is grossly disorganized, bizarre or highly inappropriate, or being in a state of catatonia
  • Negative symptoms 

However, only one of the above symptoms is required in this one month period if either one of the following conditions are met:

  • The person experiences bizarre delusions
  • The hallucinations consist either of
    • Two or more voices speaking among themselves as if in a conversation with each other
    • A voice keeping a running commentary of the person's actions or thoughts

Premorbid Symptoms of Schizophrenia

In addition, according to the DSM-IV-TR, a person with Schizophrenia must have had their disturbance for at least 6 months, during which time, besides having the one month of core symptoms described above, the following occurred:

  • The person was experiencing lower intensity psychotic-like symtpoms (ie. having odd beliefs rather than full-blown delusions, or unusual perceptual experiences that were not quite hallucinations); or, the person was experiencing Negative symptoms.  
  • The person was unable to function at their usual level in school, at work or in other roles, or to participate as usual in their relationships and in social situations. 

Subtypes of Schizophrenia

There are five subtypes of Schizophrenia:

Paranoid Type: This is when the person experiences delusions and hallucinations, but none of the other core symptoms of Schizophrenia in any major way, such as disorganized speech, disorganized behavior, catatonia or Negative symptoms

Disorganized Type: This is when a person with Schizophrenia has speech and behavior that are very disorganized and incoherent, and experiences Negative symptoms, but does not experience catatonia.

Catatonic Type: This is a type of Schizophrenia where the person predominantly experiences catatonia.

Undifferentiated Type: In this type of Schizophrenia, the person meets criteria for the general condition, but not for the Paranoid, Disorganized or Catatonic Types.

Residual Type: This is when a person with Schizophrenia experiences mainly Negative symptoms, with any of the other core symptoms only in an attenuated form.

Cognitive Deficits Associated with Schizophrenia

Another important feature of Schizophrenia are the cognitive deficits that can be associated with this condition. Because these deficits do not necessarily occur in every case of Schizophrenia, they are not included among the diagnostic criteria listed by the DSM-IV-TR.

Diagnostic Exclusions

A diagnosis of Schizophrenia cannot be made if the core symptoms are caused by a general medical condition or a drug. 

If any Major Depressive, Manic or Mixed Episodes occured during the period since the disturbance began, these would have lasted very briefly. Otherwise, the person's condition would more likely be diagnosed as either Schizoaffective Disorder, Bipolar I Disorder, or Major Depressive Episode with psychotic features

If the person has Autistic Spectrum Disorder, then a diagnosis of Schizophrenia can only be made if there is a one month period of prominent delusions or hallucinations.

 

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Overview

Positive and Negative Symptoms