Delusion

• 1. Introduction

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  A delusion is a fixed belief that will not bend, even when the evidence stacks against it. That single quality, the refusal to change in light of contradiction, is what separates a delusion from a simple mistake. A person working from false or incomplete information can review the facts and adjust. A person in the grip of a delusion cannot. The line, though, is not always clean. As one quoted definition puts it, the distinction between a delusion and a strongly held idea is sometimes difficult to make. It depends in part on the degree of conviction held despite clear or reasonable contradictory evidence. So how do clinicians decide where conviction ends and pathology begins? What happens in the brain when belief stops responding to reality? And why might a belief that looks delusional turn out to be true all along?

• 2. Four Families Of False Belief

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  Bizarre delusions are judged by a strict test: they must be clearly implausible and not understandable to same-culture peers, and they cannot derive from ordinary life experiences. The DSM-5 offers an example, a belief that someone replaced all of one's internal organs with another person's, leaving no scar. Non-bizarre delusions sit closer to reality. They are false, yet reflect real-life situations and remain at least technically possible, such as a conviction that one is under constant police surveillance. Mood-congruent delusions track a person's emotional state. A depressed person might believe television news anchors strongly disapprove of them, while someone in a manic state might believe they are a powerful deity. Mood-neutral delusions stand apart from feeling entirely, like the belief that an extra limb is growing from the back of one's head. French psychiatry, shaped by psychoanalysis, adds a further split. The paranoid delusion, seen in schizophrenia, is non-systematized, disorganized, marked by confused speech and thought. The paranoiac delusion, seen in paraphrenia, is highly systematized, organized and clear, and fixed on a single theme.

• 3. The Recurring Themes

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  Delusion of control names a specific dread: the false belief that another person, group, or external force directs one's own thoughts, feelings, impulses, or behaviors. Thought broadcasting is its cousin, the conviction that other people can know one's thoughts, while thought insertion is the belief that another mind thinks through one's own. Delusional jealousy fixes on a spouse or lover believed to be having an affair, with no proof behind the accusation. Delusion of reference assigns personal meaning to insignificant remarks, events, or objects in the environment. As the source notes, the meaning is usually negative, but the messages can also carry a grandiose quality. Erotomania reverses the direction of jealousy, holding that another person is in love with the affected individual. Somatic delusions turn inward toward the body, often the belief that one is diseased, abnormal, or changed. A vivid example is delusional parasitosis, the sensation of being infested with insects, mites, worms, or other organisms. Delusion of poverty convinces a person they are financially incapacitated. The source notes it is less common now but was widespread in the days before state support.

• 4. Grandeur And Persecution

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  Grandiose delusions trade in fantastical beliefs that one is famous, omnipotent, or otherwise very powerful, often with a supernatural, science-fictional, or religious bent. They are principally a subtype of delusional disorder but can appear as a symptom of schizophrenia and the manic episodes of bipolar disorder. In everyday speech, someone who overestimates their own abilities is said to have delusions of grandeur, though that is usually excessive pride rather than any actual delusion. The clinical form can also be linked to megalomania. Persecutory delusions are the most common type of all. They carry the theme of being followed, harassed, cheated, poisoned, conspired against, spied on, or otherwise obstructed. For a belief to qualify as persecutory, two elements must be present: harm is occurring or going to occur, and the persecutors intend to cause it. The DSM-IV-TR identifies persecutory delusions as the most common form in schizophrenia, where a person believes they are being tormented, followed, sabotaged, tricked, spied on, or ridiculed. When the focus narrows to remedying some injustice through legal action, the pattern is sometimes called querulous paranoia.

• 5. Why Belief Breaks

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  The genetic or biological theory holds that close relatives of people with delusional disorder face an increased risk of developing delusional traits. A second account, dysfunctional cognitive processing, traces delusions to distorted ways individuals view themselves. A third, the theory of motivated or defensive delusions, suggests that predisposed people develop the condition while struggling to cope with life and protect their self-esteem, casting others as the cause of their difficulties to preserve a positive self-concept. Poor hearing or sight raises the likelihood of delusional thinking. So do ongoing stressors such as immigration, low socioeconomic status, and the possible accumulation of smaller daily struggles. Higher levels of dopamine signal disorders of brain functioning. A preliminary 2002 study examined elevated dopamine in sustaining certain delusions, asking whether schizophrenia was linked to dopamine abnormalities. People with delusions of jealousy and persecution showed different levels of the dopamine metabolite HVA and homovanillyl alcohol, a difference that may be genetic. The authors cautioned the results were preliminary and called for research with a larger population, noting that age and gender also exert influence.

• 6. The Brain And The Culture

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  The two-factor model holds that delusions require dysfunction in both belief formation systems and belief evaluation systems. Neuroimaging points to the right lateral prefrontal cortex as the site of evaluation failure, regardless of delusion content, matching its role in conflict monitoring in healthy people. Abnormal activation and reduced volume appear there in people with delusions, and in frontotemporal dementia, psychosis, and Lewy body dementia. Lesions to that region are tied to jumping to conclusions, and damage there is linked to post-stroke delusions. The aberrant salience model offers a different lens, proposing that delusions arise when people assign excessive importance to irrelevant stimuli. Capgras delusions have been associated with occipito-temporal damage and a possible failure to elicit normal emotions or memories in response to faces. Culture, meanwhile, has what the source calls a decisive influence in shaping delusions. Delusions of guilt and punishment are frequent in Austria, a Western Christian country, but not in Pakistan, where persecution is the more common theme. Tellingly, those same guilt-and-punishment delusions appeared in Austrian Parkinson's patients treated with l-dopa, a dopamine agonist.

• 7. Defining The Indefinable

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  Karl Jaspers, the psychiatrist and philosopher, set out the first four criteria for a delusional belief in his 1913 book General Psychopathology. They were certainty, held with absolute conviction; incorrigibility, not changeable by counterargument or proof; impossibility or falsity of content; and not being amenable to understanding. Only the first three remain cornerstones in the DSM-5. The fourth, the demand that a belief be ultimately un-understandable, drew fire from critics such as R. D. Laing, who argued it leaves diagnosis resting on one psychiatrist's subjective grasp of a case. Counter-examples undercut nearly every defining feature. Studies show delusions vary in intensity and conviction over time, weakening the claim that certainty is essential. Some religious or spiritual beliefs are not falsifiable at all, so they cannot be called false. And a delusion can simply turn out to be true. The clearest case is the Martha Mitchell effect, named for the wife of the attorney general who alleged illegal activity in the White House. Her claims were thought to be signs of mental illness until the Watergate scandal proved her right, and hence sane.

• 8. Treating The Untreatable Belief

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  Antipsychotic medication is the common response to delusions and other positive symptoms of psychosis, reducing symptoms with a medium effect size according to a meta-analysis. Cognitive behavioral therapy improves delusions relative to control conditions, and a meta-analysis of 43 studies found that metacognitive training reduces them at a medium to large effect size. One unusual approach turned to fiction. Drawing on R. D. Laing's hypothesis, researchers at Yale University, Ohio State University, and the Community Mental Health Center of Middle Georgia used novels and films, discussing plots and cinematography to approach delusions tangentially. Science-fiction author Philip José Farmer and Yale psychiatrist A. James Giannini took this furthest, writing the novel Red Orc's Rage. The book recursively deals with delusional adolescents treated through projective therapy, with Farmer's other novels discussed inside its fictional setting. That novel was then applied to real clinical work. Critics remain unconvinced the category itself holds together. As the psychiatrist Anthony David observed, there is no acceptable, rather than accepted, definition of a delusion, a verdict that leaves the field defining its central concept by practice rather than principle.