To be diagnosed with Schizophrenia, a person must have 2 or more of the following symptoms for a significant part of the time during a 1-month or longer period:
- Delusions - fixed, mistaken ideas that the person holds. These are often odd or incorrect ideas about themselves and the world around them.
- Hallucinations - sensations that only the person experiences. This can include voices speaking to them that only they can hear.
- Disorganized Speech - this can be switching topics frequently while talking, giving answers to questions that weren't asked or not being understandable by others.
- Very Disorganized or Catatonic Behavior - this might be childlike "silliness" or being agitated or irritated without a reason, or showing no reactions to the world around them.
- Negative Symptoms - this might be not having the full range of emotional expression that others do, having poor eye contract and little body movement; or not showing interest in participating in activities.
Additional criteria include:
- the person's level of functioning in terms of self-care, work, or relationships must show significant decline compared to before the symptoms were present.
- there must be continuous signs of disturbance for at least 6 months. This may include 1-month of active symptoms and then periods of lower symptoms where only negative symptoms are present.
- symptoms must not be part of Schizoaffective disorder or bipolar disorder or major depressive disorder with psychotic features.
- symptoms must not be the result of another medical condition or a substance/medication that was taken.
- If there is a history of autism spectrum disorder or a communication disorder, the diagnosis of schizophrenia can be made only if delusions or hallucinations are present, along with the other required symptoms of schizophrenia for at least 1 month.