How Schizophrenia Is Diagnosed

Schizophrenia is a complex mental disorder that affects the way people think, feel, and act. There is no lab test that can diagnose schizophrenia. Instead, a healthcare provider has to evaluate the clinical course and symptoms of a person with this mental disorder over time. They will determine whether someone has schizophrenia by following the diagnostic criteria set out in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5). They will also have to rule out other conditions that could be causing symptoms.

It is estimated that 0.25% to 0.64% of U.S. adults are affected by schizophrenia. Diagnosing this disorder is not easy because many people with schizophrenia do not believe they have the disorder, which complicates the path to seeking and accepting a diagnosis. Also, sometimes using drugs, such as methamphetamines or LSD, can cause a person to have schizophrenia-like symptoms.

Psychology therapy session

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Professional Screenings

Professional screenings are completed in the office of a credentialed mental health professional. This person may ask about previous medical and family history, particularly a history of any mental health conditions and substance abuse.

A mental health professional will determine if a person has schizophrenia using the DSM-5 criteria for this mental disorder.

DSM-5 Criteria

A person must experience two or more of the following symptoms for at least one month (or less if successfully treated) and at least one of these must be delusions, hallucinations, or disorganized speech:

  • Positive symptoms (those abnormally present): Hallucinations, such as hearing voices or seeing things that do not exist; paranoia; and exaggerated or distorted perceptions, beliefs, and behaviors
  • Negative symptoms (those abnormally absent): A loss of or a decrease in the ability to initiate plans, speak, express emotion, or find pleasure
  • Disorganized symptoms: Confused and disordered thinking and speech, trouble with logical thinking, and sometimes bizarre behavior or abnormal movements

Continuous signs of the disturbance must persist for at least six months. This period must include at least one month of the above symptoms (or less if successfully treated) and may include periods of prodromal or residual symptoms. During these prodromal or residual periods, the signs of the disturbance may be manifested by only negative symptoms or by two or more symptoms listed above in an attenuated form (e.g., odd beliefs, unusual perceptual experiences).

The person must also exhibit a decreased level of functioning regarding work, interpersonal relationships, or self-care. Schizoaffective disorder and depressive or bipolar disorder with psychotic features have to also be ruled out.

Symptoms of schizophrenia usually first appear in early adulthood. Men often experience initial symptoms in their late teens or early 20s, while women tend to show first signs of the illness in their 20s and early 30s.

It can be difficult to diagnose schizophrenia in teens because the first signs can include a change of friends, a drop in grades, sleep problems, and irritability, which are common and nonspecific adolescent behaviors. Other factors include isolating oneself and withdrawing from others, an increase in unusual thoughts and suspicions, and a family history of psychosis. In young people who develop schizophrenia, this stage of the disorder is called the prodromal period.

Labs and Tests

Your primary care physician will want to rule out other potential causes of schizophrenia-like symptoms. Lab tests they will perform include:

  • Complete blood count to rule out infections, anemia, or other blood cell-related abnormalities
  • Thyroid function test to rule out thyroid disorder
  • Test to check vitamin B12 level to determine whether it is deficient, which could contribute to symptoms like disorganized behavior
  • Urine tests to check for substance use and other metabolic abnormalities
  • MRI to rule out abnormalities in the brain like a tumor that may be causing schizophrenia-like symptoms
  • An electroencephalogram to look for disorders such as temporal lobe epilepsy or brain toxicity

Self/At-Home Testing

While you can only receive an official diagnosis of schizophrenia through a professional screening with a mental health professional, you can take an online screening test to better understand if you should be concerned about schizophrenia and take the initiative to seek professional help.

Mental Health America, a nonprofit organization dedicated to addressing the needs of those living with a mental illness, offers a psychosis test you can take at home. It asks about your experiences over the past month, such as whether you have had hallucinations, changes in cognition, and concerns about your mental wellness.

MindWise also offers an online screening for psychosis, which is a modified version of the Prodromal Questionnaire 16 and was developed to bring about the implementation of routine screening for psychosis risk. You can remain anonymous while taking this test. It asks about any behavior and cognition changes you have noticed. Anyone who is worried about a friend or family member having schizophrenia can take a different version of this test.

There are many variations of these at-home tests, so be sure to only complete one provided by a reputable organization such as a teaching hospital or academic institution. Do not trust tests provided or supported by a pharmaceutical company. Print or take a photo of your results, regardless of outcome, so you can discuss with your doctor and get appropriate feedback. 

Schizophrenia is a complex illness with a range of symptoms and severity, so self-checks (which may be misleading due to the subjective nature of how you interpret the questions) should not be your only way of seeking help.

Differential Diagnoses

Many other mental disorders have symptoms like delusions or obsessions, hallucinations, and disorganized speech.

The differential diagnosis includes:

  • Brief psychotic disorder
  • Major depressive disorder
  • Bipolar disorder with psychotic or catatonic features
  • Post-traumatic stress disorder
  • Schizotypal personality disorder
  • Autism spectrum disorder or communication disorders
  • Schizoaffective disorder
  • Schizophreniform disorder
  • Delusional disorder

Physical health conditions also can present in similar ways as schizophrenia. They include:

If you or a loved one is struggling with schizophrenia, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

A Word From Verywell 

Getting a diagnosis can be the most challenging, and important, step in living and coping with schizophrenia. People with this mental disorder can and do lead highly productive and rewarding lives with the appropriate treatment. To do so, you need to get an official diagnosis of schizophrenia first.

If you are worried, take a self-test at home to see whether it’s time to reach out for help. If you are worried about a friend or family member, you can also use an online screening tool to determine whether you need to take action to help your loved one. Like any chronic condition, having the right treatment and a strong support network can make all the difference.

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