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Classification and external resources
Specialty Psychiatry
ICD-10 F22
ICD-9-CM 297
DiseasesDB 33439
MeSH D003702
[edit on Wikidata]

A delusion is a mistaken belief that is held with strong conviction even in the presence of superior evidence to the contrary. As a pathology, it is distinct from a belief based on false or incomplete information, confabulation, dogma, illusion, or some other misleading effects of perception.

They have been found to occur in the context of many pathological states (both general physical and mental) and are of particular diagnostic importance in psychotic disorders including schizophrenia, paraphrenia, manic episodes of bipolar disorder, and psychotic depression.



  • certainty (held with absolute conviction)
  • impossibility or falsity of content (implausible, bizarre, or patently untrue)[2]

Furthermore, when a false belief involves a value judgment, it is only considered a delusion if it is so extreme that it cannot be, or never can be proven true. For example: a man claiming that he flew into the sun and flew back home. This would be considered a delusion,[3] unless he were speaking figuratively, or if the belief had a cultural or religious source.



This condition is more common among people who have poor hearing or sight. Also, ongoing stressors have been associated with a higher possibility of developing delusions. Examples of such stressors are immigration, low socioeconomic status, and even possibly the accumulation of smaller daily hassles.[5]

Specific delusions


Higher levels of dopamine qualify as a symptom of disorders of brain function. That they are needed to sustain certain delusions was examined by a preliminary study on delusional disorder (a psychotic syndrome) instigated to clarify if schizophrenia had a dopamine psychosis.[7] There were positive results - delusions of jealousy and persecution had different levels of dopamine metabolite HVA and homovanillyl alcohol (which may have been genetic). These can be only regarded as tentative results; the study called for future research with a larger population.

It is too simplistic to say that a certain measure of dopamine will bring about a specific delusion. Studies show age[8][9] and gender to be influential and it is most likely that HVA levels change during the life course of some syndromes.[10]


Cultural factors have "a decisive influence in shaping delusions".[12] For example, delusions of guilt and punishment are frequent in a Western, Christian country like Austria, but not in Pakistan - where it is more likely persecution.[13] Similarly, in a series of case studies, delusions of guilt and punishment were found in Austrian patients with Parkinson's being treated with l-dopa - a dopamine agonist.[14]


The two factor model of delusions posits that dysfunction in both belief formation systems and belief evaluation systems are necessary for delusions. Dysfunction in evaluations systems localized to the right lateral prefrontal cortex, regardless of delusion content, is supported by neuroimaging studies and is congruent with its role in conflict monitoring in healthy persons. Abnormal activation and reduced volume is seen in people with delusions, as well as in disorders associated with delusions such as frontotemporal dementia, psychosis and lewy body dementia. Furthermore, lesions to this region are associated with "jumping to conclusions", damage to this region is associated with post-stroke delusions, and hypometabolism this region associated with caudate strokes presenting with delusions[citation needed].


Specific regions have been associated with specific types of delusions. The volume of the hippocampus and parahippocampus is related to paranoid delusions in Alzheimer's disease, and has been reported to be abnormal post mortem in one person with delusions. Capragas delusions have been associated with occipito-temporal damage and may be related to failure to elicit normal emotions or memories in response to faces.[15]


Delusions are categorized into four different groups:

  • "Paranoid delusional Ideation" encompases multiple extremes where the subject experiences symptoms of persecution, distorted perception, on-going panic, anxiety perpetuated by constant crisis, misjudgment or paranoia in the intentions of others, rapacious mood swings, suicidal ideation, etc... What frequentlly accompanies such cases and compounds the symptoms is a dual diagnosis, usually identified as having persistent bouts of drug and alcohol abuse. Environmental triggers must be taken into consideration, socio-economic standing within ones community, familial discord at early childhood development, history of abuse should also be cited for cuasation and on-set of behaviors forming pathology.
  • Bizarre delusion: Delusions are deemed bizarre if they are clearly implausible and not understandable to same-culture peers and do not derive from ordinary life experiences.[16] An example named by the DSM-5 is a belief that someone replaced all of one's internal organs with someone else's without leaving a scar, depending on the organ in question.
  • Non-bizarre delusion: A delusion that, though false, is at least technically possible, e.g., the affected person mistakenly believes that they are under constant police surveillance. Though, a plausible reality.
  • Mood-congruent delusion: Any delusion with content consistent with either a depressive or manic state, e.g., a depressed person believes that news anchors on television highly disapprove of them, or a person in a manic state might believe they are a powerful deity.



  • Delusion of control: False belief that another person, group of people, or external force controls one's general thoughts, feelings, impulses, or behavior.[17]
  • Cotard delusion: False belief that one does not exist or has died.[18]
  • Delusional jealousy: False belief that a spouse or lover is having an affair, with no proof to back up their claim.[17]
  • Delusion of guilt or sin (or delusion of self-accusation): Ungrounded feeling of remorse or guilt of delusional intensity.[17]
  • Delusion of mind being read: False belief that other people can know one's thoughts.[17]
  • Delusion of thought insertion: Belief that another thinks through the mind of the person.[17]
  • Delusion of reference: False belief that insignificant remarks, events, or objects in one's environment have personal meaning or significance. "Usually the meaning assigned to these events is negative, but the 'messages' can also have a grandiose quality."[17]
  • Erotomania: False belief that another person is in love with them.[17]
  • Grandiose religious delusion: Belief that the affected person is a god or chosen to act as a god.[19][20]
  • Somatic delusion: 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.[17] A specific example of this delusion is delusional parasitosis: Delusion in which one feels infested with insects, bacteria, mites, spiders, lice, fleas, worms, or other organisms.
  • Delusion of poverty: Person strongly believes they are financially incapacitated. Although this type of delusion is less common now, it was particularly widespread in the days preceding state support.[21]

Grandiose delusions or delusions of grandeur are principally a subtype of delusional disorder but could possibly feature as a symptom of schizophrenia and manic episodes of bipolar disorder.[22] Grandiose delusions are characterized by fantastical beliefs that one is famous, omnipotent or otherwise very powerful. The delusions are generally fantastic, often with a supernatural, science-fictional, or religious bent. In colloquial usage, one who overestimates one's own abilities, talents, stature or situation is sometimes said to have "delusions of grandeur". This is generally due to excessive pride, rather than any actual delusions. Grandiose delusions or delusions of grandeur can also be associated with megalomania.[citation needed]

Persecutory delusions


  1. harm is occurring, or is going to occur.






Delusions do not necessarily have to be false or 'incorrect inferences about external reality'.[27] Some religious or spiritual beliefs by their nature may not be falsifiable, and hence cannot be described as false or incorrect, no matter whether the person holding these beliefs was diagnosed as delusional or not.[28]




In other situations the delusion may turn out to be true belief.[31] For example, in delusional jealousy, where a person believes that their partner is being unfaithful (and may even follow them into the bathroom believing them to be seeing their lover even during the briefest of partings), it may actually be true that the partner is having sexual relations with another person. In this case, the delusion does not cease to be a delusion because the content later turns out to be verified as true or the partner actually chose to engage in the behavior of which they were being accused.

In other cases, the belief may be mistakenly assumed to be false by a doctor or psychiatrist assessing it, just because it seems to be unlikely, bizarre or held with excessive conviction. Psychiatrists rarely have the time or resources to check the validity of a person’s claims leading to some true beliefs to be erroneously classified as delusional.[32] This is known as the Martha Mitchell effect, after the wife of the attorney general who alleged that illegal activity was taking place in the White House. At the time, her claims were thought to be signs of mental illness, and only after the Watergate scandal broke was she proved right (and hence sane).


Another difficulty with the diagnosis of delusions is that almost all of these features can be found in "normal" beliefs. For instance, if a person was holding a true belief then they will of course persist with it. This can cause the disorder to be misdiagnosed by psychiatrists. These factors have led the psychiatrist Anthony David to note that "there is no acceptable (rather than accepted) definition of a delusion."[33] In practice, psychiatrists tend to diagnose a belief as delusional if it is either patently bizarre, causing significant distress, or excessively pre-occupying the patient, especially if the person is subsequently unswayed in belief by counter-evidence or reasonable arguments.

R. D. Laing's hypothesis has been applied to some forms of projective therapy to "fix" a delusional system so that it cannot be altered by the patient. Psychiatric researchers at Yale University, Ohio State University and the Community Mental Health Center of Middle Georgia have used novels and motion picture films as the focus. Texts, plots and cinematography are discussed and the delusions approached tangentially.[34] This use of fiction to decrease the malleability of a delusion was employed in a joint project by science-fiction author Philip Jose Farmer and Yale psychiatrist A. James Giannini. They wrote the novel Red Orc's Rage, which, recursively, deals with delusional adolescents who are treated with a form of projective therapy. In this novel's fictional setting other novels written by Farmer are discussed and the characters are symbolically integrated into the delusions of fictional patients. This particular novel was then applied to real-life clinical settings.[35]Many religious beliefs hold exactly the same features, yet are not universally considered delusional. Some critical psychiatrists criticize the practice of defining one and the same belief as normal in one culture and pathological in another culture for cultural essentialism. They argue that since cultural influences are mixed, including not only parents and teachers but also peers, friends, books and the internet, and the same cultural influence can have different effects depending on earlier cultural influences, the assumption that culture can be boiled down to a few traceable, distinguishable and statistically quantifiable factors and that everything that does not fall in those factors must be biological, is not a justified assumption. Other critical psychiatrists argue that just because a person's belief is unshaken by one influence does not prove that it would remain unshaken by another. For example, a person whose beliefs are not changed by verbal correction from a psychiatrist, which is how delusion is usually diagnosed, may still change his or her mind when observing empirical evidence, only that psychiatry rarely if ever present patients with such situations.[36][37]


Sometimes a correct belief may be mistaken for a delusion, such as when the belief in question is not demonstrably false but is nevertheless considered beyond the realm of possibility. A specific variant of this is when a person is fed lies in an attempt to convince them that they are delusional, a process called gaslighting, after the 1938 play Gas Light, the plot of which centered around the process. Gaslighting is frequently used by people with antisocial personality disorder or narcissistic personality disorder. Sometimes, gaslighting can be unintentional, for example if a person, or a group of people aim to lie or cover up an issue, it can lead to the victim being gaslighted as well.[38]


Psychotherapies that may be helpful in delusional disorder include individual psychotherapy, cognitive-behavioral therapy (CBT), and family therapy.

See also


  2. ^ Jaspers 1997, p. 106
  3. ^ "Terms in the Field of Psychiatry and Neurology". Archived from the original on 19 August 2010. Retrieved 6 August 2010. 
  4. ^ "Delusional Disorder". Retrieved 6 August 2010. 
  5. ^ Kingston, C. & Schuurmans-Stekhoven, J. (2016). Life hassles and delusional ideation: Scoping the potential role of cognitive and affective mediators, Psychology and Psychotherapy: Theory, Research and Practice 89(4), 445-463. doi:10.1111/papt.12089
  7. ^ Morimoto K, Miyatake R, Nakamura M, Watanabe T, Hirao T, Suwaki H (June 2002). "Delusional disorder: molecular genetic evidence for dopamine psychosis". Neuropsychopharmacology. 26 (6): 794–801. doi:10.1016/S0893-133X(01)00421-3. PMID 12007750. 
  8. ^ Mazure CM, Bowers MB (1 February 1998). "Pretreatment plasma HVA predicts neuroleptic response in manic psychosis". Journal of Affective Disorders. 48 (1): 83–6. doi:10.1016/S0165-0327(97)00159-6. PMID 9495606. 
  9. ^ Yamada N, Nakajima S, Noguchi T (February 1998). "Age at onset of delusional disorder is dependent on the delusional theme". Acta Psychiatrica Scandinavica. 97 (2): 122–4. doi:10.1111/j.1600-0447.1998.tb09973.x. PMID 9517905. 
  10. ^ Tamplin A, Goodyer IM, Herbert J (1 February 1998). "Family functioning and parent general health in families of adolescents with major depressive disorder". Journal of Affective Disorders. 48 (1): 1–13. doi:10.1016/S0165-0327(97)00105-5. PMID 9495597. 
  12. ^ Draguns JG, Tanaka-Matsumi J (July 2003). "Assessment of psychopathology across and within cultures: issues and findings". Behav Res Ther. 41 (7): 755–76. doi:10.1016/S0005-7967(02)00190-0. PMID 12781244. 
  13. ^ Stompe T, Friedman A, Ortwein G, et al. (1999). "Comparison of delusions among schizophrenics in Austria and in Pakistan". Psychopathology. 32 (5): 225–34. doi:10.1159/000029094. PMID 10494061. 
  15. ^ Naasan, George. "The Anatomy of Delusions". In Lehner, T; Miller, B; State, M. Genomics, Circuits, and Pathways in Clinical Neuropsychiatry. Elsevier Science. p. 366-369. 
  16. ^ Diagnostic and statistical manual of mental disorders: DSM-5. American Psychiatric Association. 2013. 
  17. ^ a b c d e f g h i "Delusions". Encyclopedia of Mental Disorders. Retrieved 2018-04-22. 
  18. ^ Berrios G.E.; Luque R. (1995). "Cotard Syndrome: clinical analysis of 100 cases". Acta Psychiatrica Scandinavica. 91 (3): 185–188. doi:10.1111/j.1600-0447.1995.tb09764.x. PMID 7625193. 
  19. ^ "Religious delusions are common symptoms of schizophrenia". Retrieved 17 April 2011. 
  20. ^ M, Raja. "Religious delusion" (PDF). Archived from the original (PDF) on 22 March 2012. Retrieved 17 April 2011. 
  26. ^ Myin-Germeys I, Nicolson NA, Delespaul PA (April 2001). "The context of delusional experiences in the daily life of patients with schizophrenia". Psychol Med. 31 (3): 489–98. doi:10.1017/s0033291701003646. PMID 11305857. 
  27. ^ Spitzer M (1990). "On defining delusions". Compr Psychiatry. 31 (5): 377–97. doi:10.1016/0010-440X(90)90023-L. PMID 2225797. 
  28. ^ Young, A.W. (2000). "Wondrous strange: The neuropsychology of abnormal beliefs". In Coltheart M.; Davis M. Pathologies of belief. Oxford: Blackwell. pp. 47–74. ISBN 0-631-22136-0. 
  29. ^ "Diagnostic Test List for Delusions". Retrieved 6 August 2010. 
  30. ^ "A New Definition of Delusional Ideation in Terms of Model Restriction". Retrieved 6 August 2010. [permanent dead link]
  31. ^ Jones E (1999). "The phenomenology of abnormal belief". Philosophy, Psychiatry and Psychology. 6: 1–16. 
  32. ^ Maher B.A. (1988). "Anomalous experience and delusional thinking: The logic of explanations". In Oltmanns T.; Maher B. Delusional Beliefs. New York: Wiley Interscience. ISBN 0-471-83635-4. 
  33. ^ David AS (1999). "On the impossibility of defining delusions". Philosophy, Psychiatry and Psychology. 6 (1): 17–20. 
  34. ^ Giannini AJ (2001). "Use of fiction in therapy". Psychiatric Times. 18 (7): 56. 
  36. ^ D. Double 2006 "Critical Psychiatry: The Limits of Madness"
  37. ^ Gavin Davidson, Jim Campbell, Ciarán Shannon 2015 "Models of Mental Health"
  38. ^ The Sociopath Next Door by Martha Stout (2006) Harmony. ISBN 0767915828.
Cited text

Further reading

  • Arnold, K.; Vakhrusheva, J. (2015). "Resist the negation reflex: Minimizing reactance in psychotherapy of delusions" (PDF). Psychosis. doi:10.1080/17522439.2015.1095229. 
  • Bell V, Halligan PW, Ellis H (2003). "Beliefs about delusions" (PDF). The Psychologist. 16 (8): 418–423. Archived from the original (PDF) on 28 July 2011. 
  • Blackwood, Nigel J.; Howard, Robert J.; Bentall, Richard P.; Murray, Robin M. (April 2001). "Cognitive Neuropsychiatric Models of Persecutory Delusions". American Journal of Psychiatry. 158 (4): 527–539. doi:10.1176/appi.ajp.158.4.527. PMID 11282685. 
  • Coltheart M.; Davies M., eds. (2000). Pathologies of belief. Oxford: Blackwell. ISBN 0-631-22136-0. 
  • Persaud, R. (2003). From the Edge of the Couch: Bizarre Psychiatric Cases and What They Teach Us About Ourselves. Bantam. ISBN 0-553-81346-3. 
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