Editing Hallucination (section)

==Cause==
{{See also|Psychosis#Causes|l1=Psychosis (causes)}}
Hallucinations can be caused by a number of factors.<ref name="theconversation.com">{{Cite web |vauthors=Patterson C, Procter N |date=2023-05-24 |title=Hallucinations in the movies tend to be about chaos, violence and mental distress. But they can be positive too |url=http://theconversation.com/hallucinations-in-the-movies-tend-to-be-about-chaos-violence-and-mental-distress-but-they-can-be-positive-too-204547 |access-date=2023-05-28 |website=The Conversation |language=en |archive-date=2023-05-28 |archive-url=https://web.archive.org/web/20230528043352/http://theconversation.com/hallucinations-in-the-movies-tend-to-be-about-chaos-violence-and-mental-distress-but-they-can-be-positive-too-204547 |url-status=live }}</ref>

===Hypnagogic hallucination===
{{Main|Hypnagogia}}
These hallucinations occur just before falling asleep and affect a high proportion of the population: in one survey 37% of the respondents experienced them twice a week.<ref name=Ohayon>{{cite journal | vauthors = Ohayon MM, Priest RG, Caulet M, Guilleminault C | title = Hypnagogic and hypnopompic hallucinations: pathological phenomena? | journal = The British Journal of Psychiatry | volume = 169 | issue = 4 | pages = 459–467 | date = October 1996 | pmid = 8894197 | doi = 10.1192/bjp.169.4.459 | s2cid = 3086394 }}</ref> The hallucinations can last from seconds to minutes; all the while, the subject usually remains aware of the true nature of the images. These may be associated with [[narcolepsy]]. Hypnagogic hallucinations are sometimes associated with brainstem abnormalities, but this is rare.<ref name=manford>{{cite journal | vauthors = Manford M, Andermann F | title = Complex visual hallucinations. Clinical and neurobiological insights | journal = Brain | volume = 121 ( Pt 10) | issue = 10 | pages = 1819–1840 | date = October 1998 | pmid = 9798740 | doi = 10.1093/brain/121.10.1819 | doi-access = free }}</ref>

===Peduncular hallucinosis===
{{main|Peduncular hallucinosis}}
Peduncular means pertaining to the [[Cerebral peduncle|peduncle]], which is a neural tract running to and from the [[pons]] on the [[brain stem]]. These hallucinations usually occur in the evenings, but not during drowsiness, as in the case of hypnagogic hallucination. The subject is usually fully conscious and then can interact with the hallucinatory characters for extended periods of time. As in the case of [[hypnagogic hallucination]]s, insight into the nature of the images remains intact. The false images can occur in any part of the visual field, and are rarely [[wikt:polymodal|polymodal]].<ref name=manford />

===Delirium tremens===
{{main|Delirium tremens}}
One of the more enigmatic forms of visual hallucination is the highly variable, possibly polymodal [[delirium tremens]]. It is associated with withdrawal in [[alcohol use disorder]]. Individuals with delirium tremens may be agitated and confused, especially in the later stages of this disease.<ref>{{cite book |vauthors=Rahman A, Paul M |chapter=Delirium Tremens |date=2023 |chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK482134/ |title=StatPearls |access-date=2024-01-08 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29489272 |archive-date=2023-12-04 |archive-url=https://web.archive.org/web/20231204231124/https://www.ncbi.nlm.nih.gov/books/NBK482134/ |url-status=live }}</ref> Insight is gradually reduced with the progression of this disorder. Sleep is disturbed and occurs for a shorter period of time, with [[rapid eye movement sleep]].<ref>{{cite journal | vauthors = Grover S, Ghosh A | title = Delirium Tremens: Assessment and Management | journal = Journal of Clinical and Experimental Hepatology | volume = 8 | issue = 4 | pages = 460–470 | date = December 2018 | pmid = 30564004 | pmc = 6286444 | doi = 10.1016/j.jceh.2018.04.012 }}</ref>

===Parkinson's disease and Lewy body dementia===
[[Parkinson's disease]] is linked with [[Dementia with Lewy bodies|Lewy body dementia]] for their similar hallucinatory symptoms. Presence hallucinations can be an early indicator of cognitive decline in Parkinson's Disease.<ref>{{Cite web |last=Franchina |first=Phil |date=2023-06-30 |title=Presence Hallucinations as an Early Indicator of Cognitive Decline in Parkinson's Disease |url=https://www.apdaparkinson.org/article/presence-hallucinations-as-an-early-indicator-of-parkinsons-disease/ |access-date=2024-07-27 |website=American Parkinson Disease Association |language=en-US}}</ref> The symptoms strike during the evening in any part of the visual field, and are rarely [[wikt:polymodal|polymodal]]. The segue into hallucination may begin with illusions<ref>{{cite web | url = https://www.nytimes.com/2006/02/14/health/14case.html | vauthors = Derr D | archive-url = https://web.archive.org/web/20110926153757/http://www.nytimes.com/2006/02/14/health/14case.html | archive-date=2011-09-26 | title = Marilyn and Me | work = The New York Times | date = 14 February 2006 }}</ref> where sensory perception is greatly distorted, but no novel sensory information is present. These typically last for several minutes, during which time the subject may be either conscious and normal or drowsy/inaccessible. Insight into these hallucinations is usually preserved and [[REM sleep]] is usually reduced. Parkinson's disease is usually associated with a degraded [[substantia nigra]] pars compacta, but recent evidence suggests that PD affects a number of sites in the brain. Some places of noted degradation include the median [[raphe nuclei]], the [[noradrenergic]] parts of the [[locus coeruleus]], and the [[cholinergic]] neurons in the [[parabrachial area]] and [[pedunculopontine]] nuclei of the [[tegmentum]].<ref name=manford/>

===Migraine coma===
This type of hallucination is usually experienced during the recovery from a comatose state. The migraine coma can last for up to two days, and a state of depression is sometimes [[Comorbidity|comorbid]]. The hallucinations occur during states of full consciousness, and insight into the hallucinatory nature of the images is preserved. It has been noted that ataxic lesions accompany the migraine coma.<ref name=manford/>

==== Migraine attacks ====
{{see also|Migraine aura|Scintillating scotoma}}

Migraine attacks may result in visual hallucinations including auras and in rarer cases, auditory hallucinations.<ref>{{Cite web |last=Zegar |first=Amir |date=2022-12-15 |title=Migraine Doctor Rice Village 77005 |url=https://riceemergencyroom.com/can-migraines-cause-hallucinations/ |access-date=2024-07-27 |website=Rice Emergency Room |language=en-US}}</ref>

===Charles Bonnet syndrome===
[[Charles Bonnet syndrome]] is the name given to visual hallucinations experienced by a partially or severely [[Visual impairment|sight impaired]] person. The hallucinations can occur at any time and can distress people of any age, as they may not initially be aware that they are hallucinating. They may fear for their own mental health initially, which may delay them sharing with carers until they start to understand it themselves. The hallucinations can frighten and disconcert as to what is real and what is not. The hallucinations can sometimes be dispersed by eye movements, or by reasoned logic such as, "I can see fire but there is no smoke and there is no heat from it" or perhaps, "We have an infestation of rats but they have pink ribbons with a bell tied on their necks." Over elapsed months and years, the hallucinations may become more or less frequent with changes in ability to see. The length of time that the sight impaired person can have these hallucinations varies according to the underlying speed of eye deterioration. A differential diagnosis are ophthalmopathic hallucinations.<ref>{{cite journal | vauthors = Engmann B |title=Phosphene und Photopsien – Okzipitallappeninfarkt oder Reizdeprivation? |trans-title=Phosphenes and photopsias - ischaemic origin or sensorial deprivation? - Case history |journal=Zeitschrift für Neuropsychologie |volume=19 |issue=1 |pages=7–13 |year=2008 |doi=10.1024/1016-264X.19.1.7 |language=de }}</ref>

===Focal epilepsy===
Visual hallucinations due to [[focal seizure]]s differ depending on the region of the brain where the seizure occurs. For example, visual hallucinations during [[occipital lobe]] seizures are typically visions of brightly colored, geometric shapes that may move across the [[visual field]], multiply, or form concentric rings and generally persist from a few seconds to a few minutes. They are usually unilateral and localized to one part of the visual field on the contralateral side of the seizure focus, typically the [[Temporal lobe|temporal field]]. However, unilateral visions moving horizontally across the [[visual field]] begin on the contralateral side and move toward the ipsilateral side.<ref name="Panayiotopoulos_2007" /><ref name="Teeple_2009">{{cite journal | vauthors = Teeple RC, Caplan JP, Stern TA | title = Visual hallucinations: differential diagnosis and treatment | journal = Primary Care Companion to the Journal of Clinical Psychiatry | volume = 11 | issue = 1 | pages = 26–32 | year = 2009 | pmid = 19333408 | pmc = 2660156 | doi = 10.4088/PCC.08r00673 }}</ref>

[[Temporal lobe epilepsy|Temporal lobe seizures]], on the other hand, can produce complex visual hallucinations of people, scenes, animals, and more as well as distortions of [[visual perception]]. Complex hallucinations may appear to be real or unreal, may or may not be distorted with respect to size, and may seem disturbing or affable, among other variables. One rare but notable type of hallucination is [[heautoscopy]], a hallucination of a mirror image of one's self. These "other selves" may be perfectly still or performing complex tasks, may be an image of a younger self or the present self, and tend to be briefly present. Complex hallucinations are a relatively uncommon finding in temporal lobe epilepsy patients. Rarely, they may occur during occipital focal seizures or in [[parietal lobe]] seizures.<ref name="Panayiotopoulos_2007" />

Distortions in visual perception during a temporal lobe seizure may include size distortion ([[micropsia]] or [[macropsia]]), distorted perception of movement (where moving objects may appear to be moving very slowly or to be perfectly still), a sense that surfaces such as ceilings and even entire horizons are moving farther away in a fashion similar to the [[Dolly zoom|dolly zoom effect]], and other illusions.<ref>{{cite journal | vauthors = Bien CG, Benninger FO, Urbach H, Schramm J, Kurthen M, Elger CE | title = Localizing value of epileptic visual auras | journal = Brain | volume = 123 ( Pt 2) | issue = 2 | pages = 244–253 | date = February 2000 | pmid = 10648433 | doi = 10.1093/brain/123.2.244 | doi-access = free }}</ref> Even when consciousness is impaired, insight into the hallucination or illusion is typically preserved.<ref>{{Cite journal |last1=Teeple |first1=Ryan C. |last2=Caplan |first2=Jason P. |last3=Stern |first3=Theodore A. |date=2009-02-15 |title=Visual Hallucinations: Differential Diagnosis and Treatment |url=https://www.psychiatrist.com/pcc/visual-hallucinations-differential-diagnosis-treatment |journal=The Primary Care Companion to the Journal of Clinical Psychiatry |volume=11 |issue=1 |pages=26–32 |doi=10.4088/PCC.08r00673 |pmid=19333408 |pmc=2660156 |issn=1523-5998}}</ref>

===Drug-induced hallucination===
{{main|Hallucinogen}}
Drug-induced hallucinations are caused by [[hallucinogen]]s, [[dissociative]]s, and [[deliriants]], including many drugs with [[anticholinergic]] actions and certain stimulants, which are known to cause visual and auditory hallucinations. Some psychedelics such as [[lysergic acid diethylamide]] (LSD) and [[psilocybin]] can cause hallucinations that range in the spectrum of mild to intense.{{citation needed|date=January 2024}}

Hallucinations, [[pseudohallucination]]s, or intensification of [[pareidolia]], particularly auditory, are known side effects of [[opioid]]s to different degrees—it may be associated with the absolute degree of agonism or antagonism of especially the [[kappa opioid receptor]], [[sigma receptor]]s, [[delta opioid receptor]] and the [[NMDA receptor]]s or the overall receptor activation profile as synthetic opioids like those of the [[pentazocine]], [[levorphanol]], [[fentanyl]], [[pethidine]], [[methadone]] and some other families are more associated with this side effect than natural opioids like [[morphine]] and [[codeine]] and semi-synthetics like [[hydromorphone]], amongst which there also appears to be a stronger correlation with the relative analgesic strength. Three opioids, [[Cyclazocine]] (a benzormorphan opioid/pentazocine relative) and two levorphanol-related [[morphinan]] opioids, [[Cyclorphan]] and Dextrorphan are classified as hallucinogens, and [[Dextromethorphan]] as a dissociative.<ref>{{cite web|url=https://www.mayoclinic.org/drugs-supplements/fentanyl-transdermal-route/side-effects/drg-20068152|title=Fentanyl (Transdermal Route) Side Effects - Mayo Clinic|website=[[Mayo Clinic]]|archive-url=https://web.archive.org/web/20180424203224/https://www.mayoclinic.org/drugs-supplements/fentanyl-transdermal-route/side-effects/drg-20068152|archive-date=2018-04-24|url-status=live|access-date=2018-04-24}}</ref><ref>{{cite web |url=https://www.drugs.com/pro/talwin-injection.html |title=Talwin Injection - FDA prescribing information, side effects and uses |access-date=2018-04-24 |url-status=live |archive-url=https://web.archive.org/web/20180424202933/https://www.drugs.com/pro/talwin-injection.html |archive-date=2018-04-24 }}</ref><ref>{{cite web|url=https://healthyliving.azcentral.com/prescription-drugs-that-can-cause-hallucinations-12212355.html|title=Prescription Drugs That Can Cause Hallucinations|website=azcentral.com|access-date=2018-04-24|archive-date=2021-08-28|archive-url=https://web.archive.org/web/20210828095840/https://healthyliving.azcentral.com/marijuanas-effect-on-depakote-for-manic-depression-12248490.html|url-status=live}}</ref> These drugs also can induce sleep (relating to hypnagogic hallucinations) and especially the pethidines have atropine-like [[anticholinergic]] activity, which was possibly also a limiting factor in the use, the psychotomimetic side effects of potentiating morphine, [[oxycodone]], and other opioids with [[scopolamine]] (respectively in the Twilight Sleep technique and the combination drug Skophedal, which was eukodal (oxycodone), scopolamine and [[ephedrine]], called the "wonder drug of the 1930s" after its invention in Germany in 1928, but only rarely specially compounded today) (q.q.v.).<ref>{{cite journal | vauthors = Trauner R, Obwegeser H | title = The surgical correction of mandibular prognathism and retrognathia with consideration of genioplasty. I. Surgical procedures to correct mandibular prognathism and reshaping of the chin | journal = Oral Surgery, Oral Medicine, and Oral Pathology | volume = 10 | issue = 7 | pages = 677–89; contd | date = July 1957 | pmid = 13441284 | doi = 10.1016/S0030-4220(57)80063-2 }}</ref>

===Sensory deprivation hallucination===
Hallucinations can be caused by [[sensory deprivation]] when it occurs for prolonged periods of time, and almost always occurs in the modality being deprived (visual for blindfolded/darkness, auditory for muffled conditions, etc.)<ref>{{cite journal | vauthors = Mason OJ, Brady F | title = The psychotomimetic effects of short-term sensory deprivation | language = en-US | journal = The Journal of Nervous and Mental Disease | volume = 197 | issue = 10 | pages = 783–785 | date = October 2009 | pmid = 19829208 | doi = 10.1097/NMD.0b013e3181b9760b | s2cid = 23079468 }}</ref>

===Experimentally-induced hallucinations===
{{Main|Hallucinations in the sane}}
'''Anomalous experiences''', such as so-called benign hallucinations, may occur in a person in a state of good mental and physical health, even in the apparent absence of a transient trigger factor such as [[fatigue (medical)|fatigue]], [[Substance intoxication|intoxication]] or [[sensory deprivation]].

The evidence for this statement has been accumulating for more than a century. Studies of benign hallucinatory experiences go back to 1886 and the early work of the [[Society for Psychical Research]],<ref>{{cite book | vauthors = Gurney E, Myers FW, Podmore F | date = 1886 | title = Phantasms of the Living, Vols. I and II | location = London | publisher = Trubner and Co. }}</ref><ref>{{cite journal | vauthors = Sidgwick E, Johnson A, etal | date = 1894 | title = Report on the Census of Hallucinations | location =  London | journal = Proceedings of the Society for Psychical Research | volume = X }}</ref> which suggested approximately 10% of the population had experienced at least one hallucinatory episode in the course of their life. More recent studies have validated these findings; the precise incidence found varies with the nature of the episode and the criteria of "hallucination" adopted, but the basic finding is now well-supported.<ref>{{cite book | vauthors = Slade PD, Bentall RP | date = 1988 | title = Sensory Deception: a scientific analysis of hallucination | location = London | publisher = Croom Helm }}</ref>

===Non-celiac gluten sensitivity===
There is tentative evidence of a relationship with [[non-celiac gluten sensitivity]], the so-called "gluten psychosis".<ref name="LosurdoPrincipi2018">{{cite journal | vauthors = Losurdo G, Principi M, Iannone A, Amoruso A, Ierardi E, Di Leo A, Barone M | title = Extra-intestinal manifestations of non-celiac gluten sensitivity: An expanding paradigm | journal = World Journal of Gastroenterology | volume = 24 | issue = 14 | pages = 1521–1530 | date = April 2018 | pmid = 29662290 | pmc = 5897856 | doi = 10.3748/wjg.v24.i14.1521 | type = Review | doi-access = free }}</ref>