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Diagnosing Schizophrenia

Schizophrenia is a chronic, or lifelong, brain disorder that interferes with a person’s thoughts, feelings, and behaviors. People with schizophrenia may have hallucinations, delusional or distorted thoughts, or feelings of paranoia. 

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Hearing voices is the most common type of hallucination among people with schizophrenia. They may hear these voices talking directly to them about their behavior, ordering them to do things, or warning them of danger. They may also hear these voices talking to each other. People with schizophrenia may hear voices for a long time before their family and friends notice a change in their behavior.

They also may have have firmly held beliefs that others find irrational. These delusions may include paranoid beliefs that others intend to harm them, or are spying on them, or are reading their mind. These delusions can involve a wide range of beliefs that others in the same cultural community find to be strange and contrary to their experience.

Symptoms of Schizophrenia

Schizophrenia is a common form of psychosis, a medical condition that skews the way a person perceives reality. A sudden change in personality and behavior, which occurs when a person with schizophrenia mentally “disconnects” from reality—when they can’t tell what is real from what is imagined—is called a psychotic episode. Hallucinations and delusions are part of psychosis, and people with schizophrenia often experience psychotic episodes.

Psychosis can have many causes, and the process of diagnosis often involves ruling out other conditions that can produce similar symptoms, such as substance use, depression, or bipolar disorder. Symptoms of schizophrenia can vary and even change over time. 

People with schizophrenia may have poor interpersonal skills. They are sometimes unable to show emotion and may have difficulty initiating a conversation or participating in other activities. Personal hygiene may deteriorate, and some people experience a decline in cognitive functioning, including difficulty with attention, memory, the speed of mental processing, and problem solving.

The condition affects men and women equally. It most often appears in men in their late teens or early 20s and in women in their late 20s or early 30s. Schizophrenia occurs in about 1 percent of the general population and in 10 percent of people who have a first-degree relative with the disorder, such as a parent or sibling. People who have second-degree relatives with schizophrenia, such as aunts, uncles, or grandparents, also develop the condition more often than the general population.

Causes of Schizophrenia

The exact cause of schizophrenia is not known, but scientists believe a combination of genetics and environmental factors—such as exposure to viruses while in the womb, or complications during birth, such as a baby deprived of an adequate supply of oxygen—may play a role. Imbalances in certain chemical messengers in the brain, called neurotransmitters, may also contribute to schizophrenia. Neurotransmitters transmit messages between nerve cells and the body’s muscles and organs. They play a role in mood, attentiveness, anger, learning, and memory.

Diagnostic Process

The illness often follows a progression, starting with a prodromal stage, in which the person exhibits a decline in functioning and may display very mild forms of psychosis, such as odd beliefs or unusual perceptional experiences. A diagnosis is not made until more clear-cut symptoms of psychosis emerge and only after a very careful review of all other possible causes. Our specialists are experts in this process. 

To make a diagnosis, a doctor performs a physical exam and conducts a thorough review of a person’s medical, psychiatric, and family history. The doctor may ask the person to describe any distressing experiences and perceptions. In addition, he or she asks about any concerns the person may have about achieving life goals as a result of new difficulties with motivation or cognition. Safety is also carefully assessed.

To receive a diagnosis of schizophrenia, a person must have experienced at least two of the following symptoms most of the time during a one-month period, with some level of disturbance being present for six months: 

  • delusions, such as a belief that a person is being poisoned
  • hallucinations, such as hearing a voice that issues orders
  • disorganized speech, such as logic that is difficult for others to understand
  • catatonic behavior, ranging from coma-like inactivity to hyperactivity
  • reduced ability to function, such as neglecting basic hygiene

At least one of the symptoms must be delusions, hallucinations, or disorganized speech.

In determining a diagnosis, the doctor may order additional tests, including an MRI scan or blood test. 

MRI Scan

An MRI scan—in which magnetic fields and sound waves are used to create two- or three-dimensional images—may provide a good view of the structure of the brain and rule out schizophrenia by detecting abnormalities that may be causing schizophrenia-like symptoms.

Blood Test

A routine blood test can help a doctor rule out conditions with similar symptoms, such as alcohol and drug abuse. Interactions between certain medications, such as corticosteroids and cardiovascular medications, can also cause schizophrenia-like symptoms.

At the end of an evaluation for schizophrenia, the doctor shares the diagnostic results with the person and his or her family. They then decide if they’d like to schedule a consultation appointment with an NYU Langone specialist to discuss treatment, which often includes a combination of medication and psychosocial therapy.

Our Research and Education in Schizophrenia

Learn more about our research and professional education opportunities.