Is there a test to diagnose schizophrenia?

What are the diagnostic criteria for schizophrenia?

Mental health professionals diagnose schizophrenia according to criteria from the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR).

To receive a diagnosis, an individual must exhibit at least two of the following symptoms for a significant portion of a month:

• delusions
• hallucinations
• disorganized speech, such as frequent incoherence
• disorganized or catatonic behavior, which includes periods of minimal movement or non-response
• negative symptoms, such as social withdrawal

At least one of the symptoms must be either delusions, hallucinations, or disorganized speech. These symptoms must persist for at least 6 months, with at least 1 month of active symptoms. Additionally, these symptoms must cause significant impairment in social, occupational, or personal functioning.

Some people will experience symptoms during a prodromal phase, which occurs before severe symptoms emerge in a psychosis phase. For example, people may become socially withdrawn or start to experience disorganized thoughts.

Healthcare professionals comprehensively assess someone’s medical history, symptoms, and signs of schizophrenia according to these criteria to diagnose the condition. They may also need to speak to family members, friends, and others who interact with the person.

Learn more about schizophrenia.

Tests to rule out other conditions

Schizophrenia is a complex condition with wide-ranging symptoms, making it challenging to diagnose. The symptoms can overlap with other conditions or have another cause, such as recreational drug use. For example, methamphetamines can cause schizophrenia-like symptoms.

Healthcare professionals may perform various tests to rule out other conditions.

Brain imaging tests

Healthcare professionals may use brain imaging scans, such as MRI scans or CT scans, to rule out brain tumors, structural abnormalities, or other neurological conditions that could cause schizophrenia-like symptoms.

Blood tests

Healthcare professionals may use blood tests to check for other conditions causing psychiatric symptoms, such as thyroid dysfunction. They can also use these tests to detect drug or alcohol use, which can also cause similar symptoms.

Brain activity tests

An EEG can help rule out seizure disorders, tumors, or dementia, which may present with symptoms similar to schizophrenia.

Toxicology screening

Doctors use toxicology screenings to detect the presence of drugs or alcohol in the body. Substance-induced psychosis can mimic the symptoms of schizophrenia.

Psychological testing

Psychological testing involves evaluating a person’s thinking and emotional functioning through structured assessments. These tests can identify issues with thinking, assess thought processes, and help differentiate schizophrenia from other mental health disorders.

Positive and negative syndrome scale

A group of researchers developed the Positive and Negative Syndrome Scale (PANSS) in 1987 to assess schizophrenia symptoms.

It helps healthcare professionals to asses two categories of symptoms:

• Positive symptoms: Positive symptoms include hallucinations and delusions.
• Negative symptoms: These symptoms can involve a loss of motivation, a loss of interest in daily activities, or social withdrawal.

Healthcare professionals use PANSS to assess the severity of symptoms and monitor treatment effectiveness.

Learn more about schizophrenia symptoms.

Rorschach inkblot test

Hermann Rorschach was a psychiatrist who developed the Rorschach inkblot test in 1921. This psychological assessment involves individuals describing what they see in a series of inkblots, including people with schizophrenia.

However, it is a controversial test that most modern psychiatric practices no longer use.

Brief Psychiatric Rating Scale

Researchers initially developed the Brief Psychiatric Rating Scale to assess the change in psychiatric symptoms across several mental health disorders, including schizophrenia.

The scale covers 18 symptoms or behaviors, such as hallucinations. Healthcare professionals may use the scale to assess schizophrenia symptom changes over time and treatment response.

SANS and SAPS tests

The Scale for the Assessment of Negative Symptoms (SANS) and the Scale for the Assessment of Positive Symptoms (SAPS) are well-established tools for assessing schizophrenia symptoms.

SANS focuses on negative symptoms, such as emotional flatness and social withdrawal. Conversely, SAPS assesses positive symptoms, such as hallucinations and delusions.

Calgary Depression Scale for Schizophrenia

The Calgary Depression Scale for Schizophrenia (CDSS) is a nine-item scale that assesses depression symptoms in people with schizophrenia.

Depression is common in those with schizophrenia and can complicate diagnosis and treatment. The CDSS helps healthcare professionals identify depression from negative, positive, or other schizophrenia symptoms.

Clinical global impression-schizophrenia

The Clinical Global Impression-Schizophrenia (CGI-SCH) scale assesses the overall severity of schizophrenia. It helps healthcare professionals evaluate the effectiveness of treatments over time by comparing a person’s baseline symptoms to their current symptoms.

The CGI-SCH also provides a global assessment of the person’s functioning.

Summary

Diagnosing schizophrenia is a varied process that involves clinical assessment, ruling out other medical conditions, and using various psychological tools.

There is no single test for diagnosing the condition, but doctors follow the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR) criteria to form their assessment.

Ruling out other causes is an important part of the diagnostic process, so doctors may order tests that include brain imaging and blood tests.