Delusional Disorder

Article Author:
Shawn Joseph

Article Editor:
Waquar Siddiqui

Editors In Chief:
Zina Clark
Barbara Simmons

Managing Editors:
Orawan Chaigasame
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Abdul Waheed
Frank Smeeks
Kristina Soman-Faulkner
Benjamin Eovaldi
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Pritesh Sheth
Hassam Zulfiqar
Steve Bhimji
John Shell
Matthew Varacallo
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Hajira Basit
Phillip Hynes
Kavin Sugumar

6/4/2019 12:51:25 PM


A delusion is a fixed false belief based on an inaccurate interpretation of an external reality despite evidence to the contrary. The belief is not congruent with one’s culture or subculture, and almost everyone else knows it to be false.[1]

The diagnosis of a delusional disorder occurs when a person has one or more non-bizarre (situations that can take place in real life, although not real but are possible) delusional thought for one month or more, that has no explanation by another physiological, substance-induced, medical condition or any other mental health condition. An individual's cultural beliefs merit consideration before coming to the diagnosis. Cultural beliefs also impact the content of delusions. 

Other than the delusions(s) the functionality is not impacted, and behavior is not obviously bizarre.

Some of the most frequently encountered types of delusions are:

  1. Delusional jealousy - That one’s sexual partner is unfaithful
  2. Bizarre - A delusion involving a phenomenon that is impossible, not understandable and unrelated to normal life
  3. Erotomanic - A delusion that another person, more frequently someone of higher status is in love with the individual
  4. Grandiose - A conviction of great talent, discovery, inflated self-worth, power, knowledge or relationship with someone famous or deity
  5. Persecutory - The central theme is being conspired against, attacked, harassed, obstructed in pursuit of long-term goals
  6. Somatic - These involve bodily functions and sensations
  7. Mixed - No single theme is prevalent
  8. Thought broadcasting - Delusion that one's thought is projected and perceived by others
  9. Thought insertion - A delusion that one's thought is not one's own but inserted into their mind by an external source or entity


Delusional disorder is relatively rare, has a later age of onset as compared to schizophrenia and does not show a gender predominance. The patients are also relatively stable. The exact cause of delusional disorder is unknown.[2]

Many biological conditions like substance use, medical conditions, neurological conditions can cause delusions. Delusional disorder involves the limbic system and basal ganglia in those with intact cortical functioning.[3]

Hypersensitive persons and ego defense mechanisms like reaction formation, projection and denial are some psychodynamic theories for delusional disorder. Social isolation, envy, distrust, suspicion, and low self-esteem are some of the factors which when becoming intolerable leads to a person seeking an explanation and thus form a delusion as a solution.[2]

Immigrants with language barrier, deaf and visually impaired persons as well as the elderly are special populations who are more vulnerable to delusions.


The lifetime morbid risk of delusional disorder in the general population has been estimated to range from 0.05 to 0.1 percent, based on data from various sources including case registries, case series, and population-based samples. According to the DSM-V, the lifetime prevalence of delusional disorder is about 0.02%.[3] The prevalence of delusional disorder is much rarer than other conditions like schizophrenia, bipolar disorder, and other mood disorders; this may be in part due to underreporting of delusional disorder as those with delusional disorder may not seek mental health attention unless forced by family or friends. Age mean age of onset is about 40 years, but the range is from 18 years to 90 years. The persecutory and jealous type of delusion is more common in males, while the erotomanic variety is more common in females.


Generally, global functioning is more or less preserved as compared to other disorders. Impairment can be significant in one's occupation. There may be social isolation. A unique finding is apparent normal psychological functioning and appearance when not discussing the specific delusion. 

  • Persecutory type: This is one of the most common types of delusions and patients can be anxious, irritable, aggressive or even assaultive - some patients may be litigious.
  • Jealous type: Also known as “ Othello Syndrome” this type is more common in males; it can sometimes correlate with suicidal or homicidal ideations, and hence safety is an important consideration in evaluation and management.[4]
  • Erotomanic type: Also known as “ psychose passionelle” this type of delusion involves a belief that a person usually of higher stature is in love with the patient.[5] These patients are usually socially withdrawn, dependent, sexually inhibited with a poor level of social and/or occupational functioning. “Paradoxical Conduct” is an important characteristic wherein all denials of affection are rationalized as affirmations.[6] Males with this type of delusion can be more aggressive.[7]
  • Somatic type: Also called monosymptomatic hypochondriacal psychosis and the reality impairment is severe. The patient is unarguably convinced of the severity of symptoms. The most common type of somatic delusions is that of infestation example with parasites, body dysmorphic delusion and those of body odor or halitosis. These patients also have anxiety and nervousness.
  • Grandiose type: Also known as megalomania are notable for increased self-importance.
  • Mixed type: Patients have two or more delusional themes.
  • Unspecified type: Sometimes a predominant delusion cannot be identified. Capgras syndrome is a delusional syndrome where there is a belief that a known person has been replaced by an impostor.[1] Cotard syndrome is when a patient believes he has lost his possessions, status, and even bodily organs.[1]

Delusional disorder in the partner of an individual with the delusional disorder: This is also known as a shared psychotic disorder.

History and Physical

General description: Patients usually well-nourished, appropriately groomed. May seem odd, suspicious, can be litigious. Patients seek an ally in the clinician, but it is important not to accept the delusion as it eventually results in confusing the patient’s reality and leads to distrust.[3]

Mood: Mood is usually congruent with the delusion, for example, a grandiose patient may be euphoric, or a paranoid patient may be anxious. Mild depressive symptoms are present.[8]

Perceptions: Usually no abnormal perceptions are present. Auditory hallucinations may be present in some.

Thought: This is the primary abnormality in delusional disorder. The delusions are not bizarre and are clear as well as systematic for example a cheating spouse, persecutory delusions. It is essential to check the patient's belief before concluding it to be a delusion. Some patients are verbose and circumstantial when describing their delusion. Bizarre delusions more likely correlate with schizophrenia.[3]

Cognition: Memory and cognition are usually intact, and patients are oriented unless there is a specific delusion about person, place or time.

Impulse control: It is important to evaluate for suicidal or homicidal ideations and plan. If there is a history of aggression with adverse action, then hospitalization should be considered.

Insight and judgment: Most commonly patients have no insight regarding their delusion. Judgment is assessable by a history of past behavior and future plan.


Although there is no set of labs required for delusional disorder like most other psychiatric disorders. Imaging or laboratory tests should be considered to rule out any organic causes. Substance-induced conditions should be ruled out by getting a urine drug screen. After an organic cause is ruled out a clinical exam should be completed. A clinician would do an assessment and ask further questions about their delusions. During the assessment a complete mental status exam should be done. Interviewing family members and friends should be considered because they can provide further details about the delusions and more importantly a time line of the presenting symptoms. 

Treatment / Management

The treatment of the delusional disorder is difficult considering the lack of insight. A good doctor-patient relationship is key to treatment success. Treatment includes psychotherapy by establishing trust and building a therapeutic alliance. 

Patient's history of medication compliance is the best guide to select appropriate antipsychotic medication. An antipsychotic should be started for a trial period of 6 weeks after which there is an evaluation of the effectiveness of the medication. Start a low dose and titrate up as needed. Another drug from another class can be tried after six weeks if no benefit is noted from initial treatment.[9]

Though not a primary indication drugs like lithium, valproic acid and carbamazepine can be considered as adjunct treatment if monotherapy with antipsychotics fails.

Treatment response is better when combining psychotherapy with psychopharmacology. 

Differential Diagnosis

  1. Obsessive-compulsive disorder: A person who remains convinced that his/her obsessions and compulsions are true convictions, should be given the diagnosis of obsessive-compulsive disorder with absent insight.
  2. Schizophreniform and schizophrenia: Can be differentiated from delusional disorder by the presence of other symptoms of the active phase of schizophrenia.[10]
  3. Delirium/major neurocognitive disorder: Can mimic delusional disorder but distinguished based on the chronology of symptoms.
  4. Depression or bipolar disorder: Delusions occur with mood episodes. A delusional disorder is diagnosed only when the span of delusions exceed the total duration of mood symptoms.


The prognosis of delusional disorder is better with treatment and medication compliance. Almost 50% of patients have a full recovery; more than 20% of patients report a decrease in symptoms and less than 20% of patients report minimal to no change in symptoms. A good prognosis is also related to higher social and occupational functioning, early onset before age 30 years, female, sudden onset of symptoms and short duration.[2]

Enhancing Healthcare Team Outcomes

Patients with a delusional disorder may first have their first encounter with the nurse practitioner or primary care physician. It is important to refer these patients to a mental health counselor or a psychiatrist because the management is complex. Many of these patients lack insight into their disorder and consequently refuse treatment. Despite treatment, relapses are frequent. The biggest obstacle to treatment is in treatment compliance. A mental health nurse should follow up on these patients because many eventually run into legal and work-related problems. An interprofessional team approach will ultimately result in the best patient outcomes. [Level V]

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Delusional Disorder - Questions

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Which type of delusion is most commonly seen?

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Which is not true about the etiology of delusional disorder?

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A 53-year-old female patient presents to the emergency department for a psychiatric evaluation. The patient states that her provider knows what she is thinking. Which type of delusion is the following example?

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Which of the following should not be included in a differential diagnosis for delusional disorder?

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Delusional Disorder - References


Currell EA,Werbeloff N,Hayes JF,Bell V, Cognitive neuropsychiatric analysis of an additional large Capgras delusion case series. Cognitive neuropsychiatry. 2019 Mar     [PubMed]
Mendez I,Axelson D,Castro-Fornieles J,Hafeman D,Goldstein TR,Goldstein BI,Diler R,Borras R,Merranko J,Monk K,Hickey MB,Birmaher B, Psychotic-Like Experiences in Offspring of Parents With Bipolar Disorder and Community Controls: A Longitudinal Study. Journal of the American Academy of Child and Adolescent Psychiatry. 2018 Nov 2     [PubMed]
Kalayasiri R,Kraijak K,Mutirangura A,Maes M, Paranoid schizophrenia and methamphetamine-induced paranoia are both characterized by a similar LINE-1 partial methylation profile, which is more pronounced in paranoid schizophrenia. Schizophrenia research. 2019 Feb 27     [PubMed]
Kataoka H,Sugie K, Delusional Jealousy (Othello Syndrome) in 67 Patients with Parkinson's Disease. Frontiers in neurology. 2018     [PubMed]
Kelly BD, Love as delusion, delusions of love: erotomania, narcissism and shame. Medical humanities. 2018 Mar     [PubMed]
Faden J,Levin J,Mistry R,Wang J, Delusional Disorder, Erotomanic Type, Exacerbated by Social Media Use. Case reports in psychiatry. 2017     [PubMed]
Leffa DT,Panzenhagen AC,Salvi AA,Bau CHD,Pires GN,Torres ILS,Rohde LA,Rovaris DL,Grevet EH, Systematic review and meta-analysis of the behavioral effects of methylphenidate in the spontaneously hypertensive rat model of attention-deficit/hyperactivity disorder. Neuroscience and biobehavioral reviews. 2019 Feb 28     [PubMed]
Cella M,He Z,Killikelly C,Okruszek Ł,Lewis S,Wykes T, Blending active and passive digital technology methods to improve symptom monitoring in early psychosis. Early intervention in psychiatry. 2019 Feb 28     [PubMed]
Humpston CS,Adams RA,Benrimoh D,Broome MR,Corlett PR,Gerrans P,Horga G,Parr T,Pienkos E,Powers AR 3rd,Raballo A,Rosen C,Linden DEJ, From Computation to the First-Person: Auditory-Verbal Hallucinations and Delusions of Thought Interference in Schizophrenia-Spectrum Psychoses. Schizophrenia bulletin. 2019 Feb 1     [PubMed]
Sacchetti E,Valsecchi P,Tamussi E,Paulli L,Morigi R,Vita A, Psychomotor agitation in subjects hospitalized for an acute exacerbation of Schizophrenia. Psychiatry research. 2018 Dec     [PubMed]


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