Delusional Disorder


What Is It?

Delusional disorder (sometimes called paranoid disorder) is one of the psychotic disorders. Psychosis has a variety of definitions, but it can be understood in simple terms as a gross impairment in the ability to recognize reality. Examples of psychotic symptoms are delusions (false beliefs) and hallucinations (false perceptions). Psychosis can be a part of many mental disorders including schizophrenia, mood disorders such as depression and some medical conditions.

The key feature of delusional disorder is the presence of one or more delusions, sometimes with a theme of persecution. People with this diagnosis do not have prominent mood disturbances nor do they typically have hallucinations. They do not exhibit strange forms of emotional expression, such as sometimes is seen in schizophrenia.

Delusions are false beliefs based on an incorrect interpretation of reality. The person holds the belief firmly, despite clear evidence or proof to the contrary. A religious or cultural belief that is also accepted by other members of the person’s community (an idea that is an article of faith) is not a delusion. Delusional ideas have a wide variety of themes in addition to persecution. Delusions can have jealous themes or relate to body function (somatic delusions). Ideas can be erotic or grandiose. Delusions usually involve circumstances that could occur in reality. Bizarre ideas such as being controlled by an outside force or having thoughts inserted into one’s head usually are not a feature of this illness.

Often, since people with delusional disorder are aware that their beliefs are unique, they do not talk about them. In these cases, the disorder can be detected only by observing unusual behavior that is a consequence of the belief.

Delusions, like all psychotic symptoms, can be a part of many different psychiatric disorders. The term delusional disorder is used when the problem is limited to delusional ideas or when delusions are by far the most prominent feature of the illness.

When hallucinations occur, they are part of the delusional belief. For example, someone who has the delusion that internal organs are rotting may hallucinate smells or sensations related to that delusion.

When functioning is impaired, it is a direct result of the delusion. The person may be capable of performing work, but may never leave the house because of a fear of being harmed. The lifetime risk of delusional disorder is less than one in 1,000. The cause of delusional disorder is not known.


The main symptom is a persistent delusion or delusions (a fixed belief) of something that is not happening but is plausible in real life. Types include:

  • Erotomanic — delusion of a special, loving relationship with another person, usually someone famous or of higher standing
  • Grandiose — delusion that the person has special power or ability, or a special relationship with a powerful person or figure (such as the president, a celebrity or the Pope)
  • Jealous — delusion that a sexual partner is being unfaithful
  • Persecutory — delusion that the person is being threatened or maltreated
  • Somatic — delusion of having a physical illness or defect


Since delusional disorder is rare, other major illnesses, such as schizophrenia, mood disorder or a medical problem should be considered whenever delusional ideas arise. Medical causes should be considered, especially later in life. People who develop Alzheimer’s disease, for example, can become delusional.

The diagnosis is more difficult when the affected person conceals his or her thoughts. Because the person is convinced of the reality of his or her ideas, he or she may not want help. If the person allows it, conversations with supportive family or friends can help. A general medical evaluation is useful. In a few cases, when a medical or neurological problem is suspected, diagnostic tests such as an electroencephalogram (EEG), a magnetic resonance imaging (MRI) or computed tomography (CT) scan may be suggested.

Expected Duration

The duration of this illness is highly variable. Some have a persistent delusion that waxes and wanes in its intensity and significance. In some, the disorder will last only a few months.


There is no known way to prevent this disorder.


Treatment for this disorder is difficult, especially if the delusion is of long duration. Antipsychotic medications, such as risperidone (Risperdal) and olanzapine (Zyprexa), can be helpful. Since the patient may not believe he or she has a mental disorder, it can be more difficult to engage him or her in psychotherapy. However, support, reassurance, reality testing and education all can be helpful if the person is willing to meet with a therapist. Educating the family about how to respond to the person’s needs can be useful.

When To Call A Professional

Call the person’s primary care doctor, a psychiatrist or other mental-health professional as soon as the problem is detected.


The prognosis is variable. Although the disorder can go away after a short time, delusions also can persist for months or years. The inherent reluctance of a person with this disorder to accept treatment makes the prognosis worse. However, people with this disorder retain many areas of functioning, so some do reasonably well with limited assistance.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

  A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.