Skip to content
My WebMD Sign In, Sign Up

Schizophrenia Health Center

Font Size

Mental Health and Delusional Disorder

What Are the Symptoms of Delusional Disorder?

The presence of non-bizarre delusions is the most obvious symptom of delusional disorder. Other symptoms that mighty appear include hallucinations -- seeing, hearing, or feeling things that are not really there and are related to the delusion. For example, a person who believes he or she has an odor problem may smell a bad odor.  

In contrast to schizophrenia, organization and form of thinking are not impaired in delusional disorder. In addition, mood symptoms such as depression are not prominent features in delusional disorder.


What Causes Delusional Disorder?

As with many other psychotic disorders, the exact cause of delusional disorder is not yet known. Researchers are, however, looking at the role of various genetic and biological factors.

  • Genetic: The fact that delusional disorder is more common in people who have family members with delusional disorder or schizophrenia suggests there might be a genetic factor involved. It is believed that, as with other mental disorders, a tendency to develop delusional disorder might be passed on from parents to their children.
  • Biological: Researchers are studying how abnormalities of certain areas of the brain might be involved in the development of delusional disorders. Faulty processing of information transmitted along brain circuits that involve perception and thinking are thought to play a role in psychosis.  Anti-psychotic medicines are believed to alter the flow of chemicals (neurotransmitters) such as dopamine that are important for correct information processing along these brain circuits.


How Is Delusional Disorder Diagnosed?

If symptoms of delusional disorder are present, a doctor will perform a complete medical history and physical exam. Although there are no lab tests to specifically diagnose delusional disorder, the doctor might use various diagnostic tests, such as blood tests or neuroimaging studies such as a brain MRI to rule out physical illness as the cause of the symptoms.

If the doctor finds no physical reason for the symptoms, he or she might refer the person to a psychiatrist or psychologist -- health care professionals who are specially trained to diagnose and treat mental illnesses. Psychiatrists and psychologists use specially designed interview and assessment tools to evaluate a person for a psychotic disorder. The doctor or therapist bases his or her diagnosis on reported symptoms, and his or her observation of the patient's attitude and behavior. The doctor or therapist then determines if the symptoms point to a specific disorder. A diagnosis of delusional disorder is made if a person has non-bizarre delusions for at least one month and does not have the characteristic symptoms of other psychotic disorders, such as schizophrenia.

How Is Delusional Disorder Treated?

Delusional disorder can be extremely difficult to treat. Treatment for delusional disorder most often includes medication and psychotherapy (a type of counseling). 

Psychotherapy for Delusional Disorder

WebMD Medical Reference

Today on WebMD

Mental Health Psychotic Disorders
Schizophrenia Medications
bored man resting chin on hands
10 Questions to Ask Doctor About Schizophrenia
brain scan
Schizophrenia What Increases Your Risk
mother and daughter
male patient with doctor
romantic couple
colored pencils
businesswoman working at desk at night

WebMD Special Sections