Also found in: Dictionary, Thesaurus, Legal, Idioms, Encyclopedia.




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.

Key terms

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.

Patient discussion about Delusions

Q. Give life to her please! Here is a really confusing question to you all. But your reply is a life for her. I know someone who is bipolar and she thinks that her ‘brother’ sexually molested her when they were kids. Can this be a delusion? Or hallucinating?

A. Im going to answer this question a little different;What if she is telling the truth,and her brother is planning on no body believing her? because she has this disease?---keep that in mind when you take her to the DR--mrfoot56

More discussions about Delusions
References in classic literature ?
Delusions which have been the stealthy growth of years?
Your delusion is expressed in the questions you have just put to me.
The meta-analysis, which analysed 29 studies on childhood trauma and psychotic symptoms, also found that childhood sexual abuse was associated with delusions.
Folie a deux, or induced delusional disorder, refers to the transference of delusions from the primary person (inducer) to a secondary person (recipient).
Davis of the Mayo Clinic, Rochester, Minn, noting that anxiety, depression, and medications such as opioids or treatments for attention-deficit/hyperactivity disorder can contribute to the delusions.
1] Bleuler described that the psychopathological features, especially the contents of delusions and hallucinations, [2,3] can be shaped by creating an environment due to societal developments.
This 50-year-old female had experienced seizures for 10 years and developed manic-like symptoms, delusions of jealousy, persecution and being watched, auditory hallucinations, irritable mood, and violent and disorganized behavior for the past 3 years.
has received Food and Drug Administration approval for Nuplazid (pimavanserin), indicated for the treatment of hallucinations and delusions associated with Parkinson's disease psychosis.
Delusions of grandeur, of importance, the delusion that interactive actually engages anyone beyond spotty little brats with too much time and devices at their disposal -- even the delusion that our award winners will free the world of dictators, hunger, drought and halitosis.
Food and Drug Administration today approved Nuplazid (pimavanserin) tablets, the first drug approved to treat hallucinations and delusions associated with psychosis experienced by some people with Parkinsons disease.
After giving birth to baby Arthur, Stacey suffered delusions and paranoia, believing Arthur was the son of God, and in emotional scenes, the mother and baby were separated when she was sectioned.