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A delusion is a belief that is clearly false and that indicates an abnormality in the affected person's content of thought. The false belief is not accounted for by the person's cultural or religious background or his or her level of intelligence. The key feature of a delusion is the degree to which the person is convinced that the belief is true. A person with a delusion will hold firmly to the belief regardless of evidence to the contrary. Delusions can be difficult to distinguish from overvalued ideas, which are unreasonable ideas that a person holds, but the affected person has at least some level of doubt as to its truthfulness. A person with a delusion is absolutely convinced that the delusion is real.

Delusions are a symptom of either a medical, neurological, or mental disorder. Delusions may be present in any of the following mental disorders:

  • psychotic disorders, or disorders in which the affected person has a diminished or distorted sense of reality and cannot distinguish the real from the unreal, including schizophrenia , schizoaffective disorder , delusional disorder , schizophreniform disorder , shared psychotic disorder , brief psychotic disorder , and substance-induced psychotic disorder
  • bipolar disorder
  • major depressive disorder with psychotic features
  • delirium
  • dementia

Overvalued ideas may be present in anorexia nervosa , obsessive-compulsive disorder , body dysmorphic disorder , or hypochondriasis .


Delusions are categorized as either bizarre or non-bizarre and as either mood-congruent or mood-incongruent. A bizarre delusion is a delusion that is very strange and completely implausible for the person's culture; an example of a bizarre delusion would be that aliens have removed the affected person's brain . A non-bizarre delusion is one whose content is definitely mistaken, but is at least possible; an example may be that the affected person mistakenly believes that he or she is under constant police surveillance. A mood-congruent delusion is any delusion whose content is consistent with either a depressive or manic state; for example, a depressed person may believe that the world is ending, or a person in a manic state (a state in which the person feels compelled to take on new projects, has a lot of energy, and needs little sleep) believes that he or she has special talents or abilities, or is a famous person. A mood-incongruent delusion is any delusion whose content is not consistent with either a depressed or manic state or is mood-neutral. An example is a depressed person who believes that thoughts are being inserted into his or her mind from some outside force, person, or group of people, and these thoughts are not recognized as the person's own thoughts (called "thought insertion").

In addition to these categories, delusions are often categorized according to theme. Although delusions can have any theme, certain themes are more common. Some of the more common delusion themes are:

  • Delusion of control: This is a false belief that another person, group of people, or external force controls one's thoughts, feelings, impulses, or behavior. A person may describe, for instance, the experience that aliens actually make him or her move in certain ways and that the person affected has no control over the bodily movements. Thought broadcasting (the false belief that the affected person's thoughts are heard aloud), thought insertion, and thought withdrawal (the belief that an outside force, person, or group of people is removing or extracting a person's thoughts) are also examples of delusions of control.
  • Nihilistic delusion: A delusion whose theme centers on the nonexistence of self or parts of self, others, or the world. A person with this type of delusion may have the false belief that the world is ending.
  • Delusional jealousy (or delusion of infidelity): A person with this delusion falsely believes that his or her spouse or lover is having an affair. This delusion stems from pathological jealousy and the person often gathers "evidence" and confronts the spouse about the nonexistent affair.
  • Delusion of guilt or sin (or delusion of self-accusation): This is a false feeling of remorse or guilt of delusional intensity. A person may, for example, believe that he or she has committed some horrible crime and should be punished severely. Another example is a person who is convinced that he or she is responsible for some disaster (such as fire, flood, or earthquake) with which there can be no possible connection.
  • Delusion of mind being read: The false belief that other people can know one's thoughts. This is different from thought broadcasting in that the person does not believe that his or her thoughts are heard aloud.
  • Delusion of reference: The person falsely believes that insignificant remarks, events, or objects in one's environment have personal meaning or significance. For instance, a person may believe that he or she is receiving special messages from the news anchorperson on television. Usually the meaning assigned to these events is negative, but the "messages" can also have a grandiose quality.
  • Erotomania: A delusion in which one believes that another person, usually someone of higher status, is in love with him or her. It is common for individuals with this type of delusion to attempt to contact the other person (through phone calls, letters, gifts, and sometimes stalking).
  • Grandiose delusion: An individual exaggerates his or her sense of self-importance and is convinced that he or she has special powers, talents, or abilities. Sometimes, the individual may actually believe that he or she is a famous person (for example, a rock star or Christ). More commonly, a person with this delusion believes he or she has accomplished some great achievement for which they have not received sufficient recognition.
  • Persecutory delusions: These are the most common type of delusions and involve the theme of being followed, harassed, cheated, poisoned or drugged, conspired against, spied on, attacked, or obstructed in the pursuit of goals. Sometimes the delusion is isolated and fragmented (such as the false belief that co-workers are harassing), but sometimes are well-organized belief systems involving a complex set of delusions ("systematized delusions"). A person with a set of persecutory delusions may be believe, for example, that he or she is being followed by government organizations because the "persecuted" person has been falsely identified as a spy. These systems of beliefs can be so broad and complex that they can explain everything that happens to the person.
  • Religious delusion: Any delusion with a religious or spiritual content. These may be combined with other delusions, such as grandiose delusions (the belief that the affected person was chosen by God, for example), delusions of control, or delusions of guilt. Beliefs that would be considered normal for an individual's religious or cultural background are not delusions.
  • Somatic delusion: A delusion whose content pertains to bodily functioning, bodily sensations, or physical appearance. Usually the false belief is that the body is somehow diseased, abnormal, or changed. An example of a somatic delusion would be a person who believes that his or her body is infested with parasites.

Delusions of control, nihilistic delusions, and thought broadcasting, thought insertion, and thought withdrawal are usually considered bizarre delusions. Most persecutory, somatic, grandiose, and religious delusions, as well as most delusions of jealousy, delusions of mind being read, and delusions of guilt would be considered non-bizarre.

See also Hallucinations



American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington, DC: American Psychiatric Association, 2000.

Kaplan, Harold I., M.D., and Benjamin, J. Sadock, M.D. Kaplan and Sadock's Synopsis of Psychiatry: Behavioral Sciences, Clinical Psychiatry. 8th edition. Baltimore: Williams and Wilkins, 2002.


Leeser, Jaimie, and William O'Donohue. "What is a Delusion? Epistemological Dimensions." Journal of Abnormal Psychology 108 (1999): 687-694.

Jennifer Hahn, Ph.D.

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A delusion is an unshakable belief in something untrue. These irrational beliefs defy normal reasoning, and remain firm even when overwhelming proof is presented to dispute them. Delusions are often accompanied by hallucinations and/or feelings of paranoia, which act to strengthen confidence in the delusion. Delusions are distinct from culturally or religiously based beliefs that may be seen as untrue by outsiders.


Delusions are a common symptom of several mood and personality-related mental illnesses, including schizoaffective disorder, schizophrenia, shared psychotic disorder, major depressive disorder, and bipolar disorder. They are also the major feature of delusional disorder. Individuals with delusional disorder suffer from long-term, complex delusions that fall into one of six categories: persecutory, grandiose, jealousy, erotomanic, somatic, or mixed. There are also delusional disorders such as dementia that clearly have organic or physical causes.


Individuals with persecutory delusional disorder are plagued by feelings of paranoia and an irrational yet unshakable belief that someone is plotting against them, or out to harm them.


Individuals with grandiose delusional disorder have an inflated sense of self-worth. Their delusions center on their own importance, such as believing that they have done or created something of extreme value or have a "special mission."


Jealous delusions are unjustified and irrational beliefs that an individual's spouse or significant other has been unfaithful.


Individuals with erotomanic delusional disorder believe that another person, often a stranger, is in love with them. The object of their affection is typically of a higher social status, sometimes a celebrity. This type of delusional disorder may lead to stalking or other potentially dangerous behavior.


Somatic delusions involve the belief that something is physically wrong with the individual. The delusion may involve a medical condition or illness or a perceived deformity. This condition differs from hypochondriasis in that the deformity is perceived as a fixed condition not a temporary illness.


Mixed delusions are those characterized by two or more of persecutory, grandiose, jealousy, erotomanic, or somatic themes.

Causes and symptoms

Some studies have indicated that delusions may be generated by abnormalities in the limbic system, the portion of the brain on the inner edge of the cerebral cortex that is believed to regulate emotions. The exact source of delusions has not been conclusively found, but potential causes include genetics, neurological abnormalities, and changes in brain chemistry. Delusions are also a known possible side effect of drug use and abuse (e.g., amphetamines, cocaine, PCP).


Patients with delusional symptoms should undergo a thorough physical examination and patient history to rule out possible organic causes (such as dementia). If a psychological cause is suspected, a mental health professional will typically conduct an interview with the patient and administer one of several clinical inventories, or tests, to evaluate mental status.


Delusions that are symptomatic of delusional disorder should be treated by a psychologist and/or psychiatrist. Though antipsychotic drugs are often not effective, antipsychotic medication such as thioridazine (Mellaril), haloperidol (Haldol), chlorpromazine (Thorazine), clozapine (Clozaril), or risperidone (Risperdal) may be prescribed, and cognitive therapy or psychotherapy may be attempted.


Hallucinations False or distorted sensory experiences that appear to be real perceptions.

Paranoia An unfounded or exaggerated distrust of others.

Shared psychotic disorder Also known as folie à deux; shared psychotic disorder is an uncommon disorder in which the same delusion is shared by two or more individuals.

If an underlying condition such as schizophrenia, depression, or drug abuse is found to be triggering the delusions, an appropriate course of medication and/or psychosocial therapy is employed to treat the primary disorder. The medication, typically, will include an antipsychotic agent.


Delusional disorder is typically a chronic condition, but with appropriate treatment, a remission of delusional symptoms occurs in up to 50% of patients. However, because of their strong belief in the reality of their delusions and a lack of insight into their condition, individuals with this disorder may never seek treatment, or may be resistant to exploring their condition in psychotherapy.



American Psychiatric Association. 1400 K Street NW, Washington DC 20005. (888) 357-7924.

American Psychological Association (APA). 750 First St. NE, Washington, DC 20002-4242. (202) 336-5700. ttp://

National Alliance for the Mentally Ill (NAMI). Colonial Place Three, 2107 Wilson Blvd., Ste. 300, Arlington, VA 22201-3042. (800) 950-6264.

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Understanding Delusions

Delusional Disorder Versus Schizophrenia



Delusions (dee-LOO-zhunz) are one or more false beliefs that a person holds despite either lack of evidence that the belief is true or clear evidence that the belief is not true.


for searching the Internet and other reference sources

Delusional disorder


Understanding Delusions

Imagine being completely convinced that someone is following you, to the point where you even call the police several times. Or imagine believing that your friend is spreading horrible rumors behind your back, even though there is no reason to think she is. Or imagine thinking that you are about to release a new hit record, or that there is something physically wrong with you when your doctor has found otherwise.

These thoughts may sound ridiculous, but they help to illustrate what it means to be delusional. Its normal for people to have occasional thoughts that, for example, a boss, teacher, or friend is out to get them. Delusions are different, however. A person with delusions holds on to unfounded beliefs for a long period of time (at least more than a month) and absolutely believes that they are true in spite of evidence to the contrary.

Delusions often are classified into the following subtypes:

  • erotomanic (air-ROT-oh-MAN-ik): People with erotomanic delusions falsely believe that someone is in love with them and make repeated attempts to establish contact through phone calls, letters, or stalking.
  • grandiose (gran-dee-OSE): People with grandiose delusions falsely believe that they have a great talent or have made an important discovery. These so-called delusions of grandeur involve wild exaggeration of ones own importance, wealth, power, or talents.
  • persecution: People with delusions of persecution may falsely believe that they are being plotted against, spied on, lied about, or harassed. They may repeatedly try to get justice through appeals to the court system and other government agencies.
  • jealous: This type of delusion involves a false belief that a spouse or significant other is cheating, despite a lack of supporting evidence. People with jealous delusions sometimes resort to violence.
  • somatic (so-MAT-tik): This type of delusion relates to a bodily function. For example, people with somatic delusions may falsely believe that they have a physical deformity, an unusual odor, or some kind of germ in their bodies.

Delusional Disorder Versus Schizophrenia

Delusions often are a symptom of serious psychotic (sy-KOT-ik) disorders, the most common being schizophrenia (skitz-oh-FREN-ee-uh). Besides delusions, other symptoms of schizophrenia include hallucinations*, disorganized thoughts and speech, and bizarre and inappropriate behavior. Typically, psychotic disorders affect people in late adolescence or early adulthood.

* hallucination
(huh-LOO-sihNAY-shun) is something that a person senses that is not caused by a real outside event. It can involve any of the senses:
hearing, smell, sight, taste, or touch.

Not all delusions are caused by psychotic disorders, however. When a person has delusions, and the doctor can find no psychotic disorder that is to blame, the doctor may diagnose a delusional disorder. Unlike schizophrenia and other psychotic disorders, delusional disorder usually occurs in middle age (ages 35 to 55) or later adult life. Also, it generally does not lead to severe problems with everyday functioning and thinking. Many people with delusional disorder can keep their jobs, and, on the whole, their personalities do not change. However, once delusions occur, the false beliefs often prove to be a long-term problem. Some people with delusions can become dangerous or violent, threatening harm to themselves or others.


Treatment for delusions usually involves regular meetings with a doctor who specializes in treating mental disorders. People with delusions tend to resist treatment at first and deny that there is any problem. The doctor needs to establish a cooperative relationship with the person, listening to his or her thoughts, easing any fears, and suggesting ways of coping. Some medications, particularly those used to treat depression and psychotic disorders, may help as well. Hospitalization may be necessary if the person shows signs of dangerous behavior or suicidal tendencies as a reaction to the delusional beliefs.

See also






Internet Mental Health. This is an online mental health encyclopedia founded by a Canadian psychiatrist. It provides specific information about delusional disorder and schizophrenia.

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