Delusion

Themes

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

• Delusion of control: False belief that another person, group of people, or external force controls one's general thoughts, feelings, impulses, or behaviors.^[7]
• Delusional jealousy: False belief that a spouse or lover is having an affair, with no proof to back up the claim.^[7]
• Delusion of guilt or sin (or delusion of self-accusation): Ungrounded feeling of remorse or guilt of delusional intensity.^[7]
• Thought broadcasting: False belief that other people can know one's thoughts.^[7]
• Delusion of thought insertion: Belief that another thinks through the mind of the person.^[7]
• Persecutory delusions: False belief that one is being persecuted.
• 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."^[7]
• Erotomania: False belief that another person is in love with them.^[7]
• Religious delusion: Belief that the affected person is a god or chosen to act as a god.^[11]
• 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.^[7] 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.^[12]

Grandiose delusions

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.^[13] Grandiose delusions are characterized by fantastical beliefs that one is famous, omnipotent or otherwise very powerful. The delusions are generally fantastical, 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.^[14]

Persecutory delusions

Persecutory delusions 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 otherwise obstructed in the pursuit of goals. The person affected by a persecutory delusion wrongly believes that they are being persecuted. Specifically, for a person's delusion to be defined as persecutory, they must believe the following two central elements:^{[15][page needed]}

• harm is occurring, or is going to occur
• the persecutors have the intention to cause harm

According to the DSM-IV-TR, persecutory delusions are the most common form of delusions in schizophrenia, where the person believes they are "being tormented, followed, sabotaged, tricked, spied on, or ridiculed".^[16] The DSM-IV-TR also identifies persecutory delusions as the main feature of the persecutory type of delusional disorder. When the focus is remedying some injustice by legal action, they are sometimes called "querulous paranoia".^[17]

Specific delusions

The two largest factors in the formation of delusions are disorders of brain functioning and background influences of temperament and personality.^[22]

Higher levels of dopamine are a sign of disorders of brain functioning. A preliminary 2002 study on delusional disorder (a psychotic syndrome) examined the role of elevated dopamine levels in sustaining certain delusions, in order to establish whether schizophrenia was linked to dopamine abnormalities.^[23] The results confirmed the theory, showing that individuals with delusions of jealousy and persecution had different levels of dopamine metabolite HVA and homovanillyl alcohol; the cause of this may in turn be genetic. The authors cautioned that the results were preliminary and called for future research with a larger population. Also, factors beyond dopamine impact the development of a specific delusion; studies show age^[24][25] and gender are influential and HVA levels likely change during the life course of some syndromes.^[26]

On the influence of personality, Andrew Sims wrote: "Jaspers considered there is a subtle change in personality due to the illness itself; and this creates the condition for the development of the delusional atmosphere in which the delusional intuition arises."^[27]

Cultural factors have "a decisive influence in shaping delusions".^[28] For example, delusions of guilt and punishment are frequent in Austria (a Western, Christian country), but not in Pakistan, where delusions are more often about persecution.^[29] Similarly, in a series of case studies, delusions of guilt and punishment were found in Austrian patients with Parkinson's disease being treated with l-dopa, a dopamine agonist.^[30]

Debate over definitions

The modern definition and Jaspers' original criteria have been criticised, as counter-examples can be shown for every defining feature.

Studies on psychiatric patients show that delusions vary in intensity and conviction over time, which suggests that certainty and incorrigibility are not necessary components of a delusional belief.^[39]

Delusions do not necessarily have to be false or "incorrect inferences about external reality".^[40] 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.^[41] In other situations the delusion may turn out to be true belief.^[42] 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.^{[citation needed]}

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.^[43] 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).^[44]

Similar factors have led to criticisms of Jaspers' definition of true delusions as being ultimately "un-understandable". Critics (such as R. D. Laing) have argued that this leads to the diagnosis of delusions being based on the subjective understanding of a particular psychiatrist, who may not have access to all the information that might make a belief otherwise interpretable. 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.^[45] This use of fiction to decrease the malleability of a delusion was employed in a joint project by science-fiction author Philip José 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.^[46]

Another difficulty with the diagnosis of delusions is that almost all of these features can be found in "normal" beliefs. Many religious beliefs hold exactly the same features, yet are not universally considered delusional. 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."^[47] 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.^{[citation needed]}

Psychiatrist Joseph Pierre states that one factor that helps differentiate delusions from other kinds of beliefs is that anomalous subjective experiences are often used to justify delusional beliefs. While idiosyncratic and self-referential content often make delusions impossible to share with others,^[48] Pierre suggests that it may be more helpful to emphasize the level of conviction, preoccupation, and extension of a belief rather than the content of the belief when considering whether a belief is delusional.^[49]

It is important to distinguish true delusions from other symptoms such as anxiety, fear, or paranoia. To diagnose delusions a mental state examination may be used. This test includes appearance, mood, affect, behavior, rate and continuity of speech, evidence of hallucinations or abnormal beliefs, thought content, orientation to time, place and person, attention and concentration, insight and judgment, as well as short-term memory.^[50]

Johnson-Laird suggests that delusions may be viewed as the natural consequence of failure to distinguish conceptual relevance. That is, irrelevant information would be framed as disconnected experiences, then it is taken to be relevant in a manner that suggests false causal connections. Furthermore, relevant information would be ignored as counterexamples.^[51]