There is no single test that diagnoses schizophrenia. Instead, your doctor will rule out other health issues 1 at a time. Other medical problems or drug side effects can look like the symptoms of schizophrenia. These symptoms may include delusions, hallucinations, motor function changes, or issues with mood. It is important for your healthcare team to look into these causes along with your mental health.1-4
Examples of medical issues that can mimic the symptoms of schizophrenia are:2-4
- Neurological conditions like stroke, multiple sclerosis, Alzheimer’s disease, dementia, or seizures
- Motor disorders like Parkinson’s disease or Huntington’s disease
- Infections like syphilis or HIV/AIDS
- Urinary tract infections, particularly in medically compromised people like older adults
- Liver or kidney diseases that can lead to a buildup of toxins in the bod
- Autoimmune conditions like thyroid problems or multiple sclerosis
- Recreational drug use
- Medicine side effects
- Other mental health issues like depression, anxiety, or bipolar disorder
This is not a full list of all potential issues that have similar symptoms to schizophrenia. Your doctor will work with you to figure out what you are at risk for and choose tests that are right for you.
Which doctors can diagnose schizophrenia?
The path to a diagnosis often starts with a primary care doctor. They can test for many medical issues that may cause schizophrenia-like symptoms. They will take a health history, perform a physical exam, and assess your mental health symptoms. And they may want to do blood tests or imaging tests like magnetic resonance imaging (MRI).1-3
There may be no obvious medical causes of your symptoms. At that point, a mental health diagnosis like schizophrenia is more likely. If this is the case, your primary care doctor may send you to a psychiatrist. A psychiatrist focuses on diagnosing and treating mental health conditions.1,5
Health history
The first step in the diagnostic process is taking a good health history. This can help your doctor determine what tests or images are needed. During a health history, your doctor will ask questions about your symptoms, past medical history, and family history. You or a loved one can give the answers.2-4
Possible health history questions include:2-4
- What symptoms are you noticing?
- How long have these been going on?
- Have they changed over time?
- What makes your symptoms worse or better?
- What other health issues do you have?
- What drugs (including over-the-counter drugs) do you take?
- Does anyone else in your family have similar symptoms?
- What other medical issues run in your family?
The questions may also change based on what type of doctor you are seeing. For example, your primary care doctor may ask broad questions. This can help with ordering tests to look for other health issues. If you see a psychiatrist, their questions will focus more on your mental health.5
Physical exam
Once your doctor completes your health history, they will do a physical exam. They will listen to your heart, lungs, and belly with their stethoscope. They will take your vital signs, like blood pressure and heart rate, too.6
Your doctor may also do a neurological exam. This exam includes asking questions that test your memory or coordination. A neurological exam can also include basic vision, hearing, and sensation (feeling) tests.6
Physical exams may differ from person to person based on what the doctor is looking for. Your doctor will walk you through what they are doing during the exam. You also can ask questions at any time.
Blood tests and body imaging
While there are no tests that directly diagnose schizophrenia, there are tests that can diagnose other issues with similar symptoms. Your doctor may order some of these tests to rule other conditions in or out. If these tests are negative, you may be more likely to have schizophrenia than an underlying physical issue.1
Common tests used to rule out medical causes of symptoms include:1-4
- Chemistry panel – Looks at electrolyte levels like calcium or sodium
- Complete blood count (CBC) – Looks for changes in the blood cells, such as those that fight inflammation or infection
- Liver function tests
- Thyroid function tests
- Tests for specific infections like HSV (the herpes virus), syphilis, or HIV
- Vitamin level tests
- Urinalysis – Looks for urinary tract infections or other changes in the urine
- Urine drug screening
- MRI or computed tomography (CT) scans – Look for any changes in the brain
This is not all of the potential tests your doctor may do. Talk with your healthcare team about what tests are right for you and why.
Mental status exam
In some cases, all of the tests listed above come back negative. At that point, a mental health diagnosis like schizophrenia is likely. Your doctor may send you to a mental health professional, like a psychiatrist, for an official diagnosis. A mental health specialist can give you a full mental status exam (MSE).5,6
An MSE focuses on things like:6
- Appearance
- Motor function
- Speech
- Mood or affect
- Thought content
- Thought process
- Perception
- Fund of knowledge
- Insight into current situation
- Judgment or making good decisions
DSM-5 criteria
Ultimately, the main way to make a diagnosis of schizophrenia is by using a book called the DSM-5. DSM stands for Diagnostic and Statistical Manual of Mental Disorders. It is currently in its fifth edition. It is the gold standard for diagnosing mental health issues.7
According to the DSM-5, the basic criteria to be diagnosed with schizophrenia are having:7
- Two or more of the following symptoms: delusions, hallucinations, disorganized speech, disorganized behaviors, or negative symptoms (like a lack of emotional expression, desire, or motivation). At least 1 of your symptoms must be delusions, hallucinations, or disorganized speech.
- Symptoms that affect a person’s ability to do their daily activities. This includes work, friendships, and self-care.
- Symptoms that last for 6 months or more.
- No other known cause of symptoms, like drug side effects or schizoaffective disorder (schizophrenia with a mood disorder like depression or bipolar disorder).
Your mental health provider may ask you questions about the criteria directly. They may also talk to your loved ones for help. If you meet the DSM-5 criteria and there are no other causes of your symptoms, your doctor will diagnose you with schizophrenia.7