Editing Delirium (section)

==Causes==
Delirium arises through the interaction of a number of predisposing and precipitating factors.<ref>{{cite journal | vauthors = Magny E, Le Petitcorps H, Pociumban M, Bouksani-Kacher Z, Pautas É, Belmin J, Bastuji-Garin S, Lafuente-Lafuente C | title = Predisposing and precipitating factors for delirium in community-dwelling older adults admitted to hospital with this condition: A prospective case series | journal = PLOS ONE | volume = 13 | issue = 2 | pages = e0193034 | date = 2018-02-23 | pmid = 29474380 | pmc = 5825033 | doi = 10.1371/journal.pone.0193034 | doi-access = free | bibcode = 2018PLoSO..1393034M }}</ref><ref name=Ormseth>{{cite journal | vauthors = Ormseth CH, LaHue SC, Oldham MA, Josephson SA, Whitaker E, Douglas VC | title = Predisposing and Precipitating Factors Associated With Delirium: A Systematic Review | journal = JAMA Network Open | volume = 6 | issue = 1 | pages = e2249950 | date = January 2023 | pmid = 36607634 | pmc = 9856673 | doi = 10.1001/jamanetworkopen.2022.49950 }}</ref>

Individuals with multiple and/or significant predisposing factors are at high risk for an episode of delirium with a single and/or mild precipitating factor. Conversely, delirium may only result in low risk individuals if they experience a serious or multiple precipitating factors. These factors can change over time, thus an individual's risk of delirium is modifiable (see {{section link|Delirium|Prevention}}).

===Predisposing factors===
Important predisposing factors include the following:<ref name=Ormseth /><ref name="pmid19347026">{{cite journal | vauthors = Fong TG, Tulebaev SR, Inouye SK | title = Delirium in elderly adults: diagnosis, prevention and treatment | journal = Nature Reviews. Neurology | volume = 5 | issue = 4 | pages = 210–220 | date = April 2009 | pmid = 19347026 | pmc = 3065676 | doi = 10.1038/nrneurol.2009.24 }}</ref>
* 65 or more years of age
* Cognitive impairment/[[dementia]]
* Physical morbidity (e.g., [[Heart failure|biventricular failure]], [[cancer]], [[cerebrovascular disease]])
* Psychiatric morbidity (e.g., [[depression (mood)|depression]])
* Sensory impairment (i.e., vision and hearing)
* Functional dependence (e.g., requiring assistance for self-care or mobility)
* Dehydration/[[malnutrition]]
* Substance use disorder, especially [[Alcohol abuse|alcohol use disorder]] and anticholinergic abuse.

===Precipitating factors===
[[File:An alcoholic man with delirium Wellcome L0060780 (level correction).jpg|thumb|Acute confusional state caused by [[Alcohol withdrawal syndrome|alcohol withdrawal]], also known as [[delirium tremens]]]]
Any serious, acute biological factor that affects neurotransmitter, neuroendocrine, or neuroinflammatory pathways can precipitate an episode of delirium in a vulnerable brain.<ref>{{cite journal | vauthors = Hughes CG, Patel MB, Pandharipande PP | title = Pathophysiology of acute brain dysfunction: what's the cause of all this confusion? | journal = Current Opinion in Critical Care | volume = 18 | issue = 5 | pages = 518–526 | date = October 2012 | pmid = 22941208 | doi = 10.1097/MCC.0b013e328357effa | s2cid = 22572990 }}</ref> Certain elements of the clinical environment have also been associated with the risk of developing delirium.<ref>{{cite journal | vauthors = McCusker J, Cole M, Abrahamowicz M, Han L, Podoba JE, Ramman-Haddad L | title = Environmental risk factors for delirium in hospitalized older people | journal = Journal of the American Geriatrics Society | volume = 49 | issue = 10 | pages = 1327–1334 | date = October 2001 | pmid = 11890491 | doi = 10.1046/j.1532-5415.2001.49260.x | s2cid = 22910426 }}</ref> Some of the most common precipitating factors are listed below:<ref name=Ormseth /><ref name="Inouye2006" />
* Prolonged sleep restriction or deprivation
* Environmental, psychophysiological stress (as found in acute care settings)
** Inadequately controlled pain
** Immobilization, use of physical restraints<ref>{{cite journal | vauthors = Rollo E, Callea A, Brunetti V, Vollono C, Marotta J, Imperatori C, Frisullo G, Broccolini A, Della Marca G | title = Delirium in acute stroke: A prospective, cross-sectional, cohort study | journal = European Journal of Neurology | volume = 28 | issue = 5 | pages = 1590–1600 | date = May 2021 | pmid = 33476475 | doi = 10.1111/ene.14749 | s2cid = 231677499 }}</ref>
** Urinary retention, use of bladder catheter
** Emotional stress
** Severe constipation/fecal impaction
* Medications<ref name="CleggYoung">{{cite journal | vauthors = Clegg A, Young JB | title = Which medications to avoid in people at risk of delirium: a systematic review | journal = Age and Ageing | volume = 40 | issue = 1 | pages = 23–29 | date = January 2011 | pmid = 21068014 | doi = 10.1093/ageing/afq140 | doi-access = free }}</ref><ref>{{cite journal | vauthors = McCoy TH, Castro VM, Hart KL, Perlis RH | title = Stratified delirium risk using prescription medication data in a state-wide cohort | journal = General Hospital Psychiatry | volume = 71 | pages = 114–120 | date = July 2021 | pmid = 34091195 | pmc = 8249339 | doi = 10.1016/j.genhosppsych.2021.05.001 }}</ref>
** Sedatives ([[benzodiazepine]]s, [[opioid]]s), [[anticholinergics]], [[dopaminergic]]s, corticosteroids, [[polypharmacy]]
** General anesthetic
** Substance intoxication or withdrawal
* Primary neurologic conditions
** Severe drop in blood pressure, relative to the person's normal blood pressure ([[orthostatic hypotension]]) resulting in inadequate blood flow to the brain ([[cerebral hypoperfusion]])
** [[Stroke]]/[[transient ischemic attack]](TIA)
** [[Intracranial hemorrhage|Intracranial bleeding]]
** [[Meningitis]], [[encephalitis]]
* Concurrent illness
** Infections – especially respiratory (e.g. [[pneumonia]], [[COVID-19]]<ref>{{cite journal | vauthors = Saini A, Oh TH, Ghanem DA, Castro M, Butler M, Sin Fai Lam CC, Posporelis S, Lewis G, David AS, Rogers JP | title = Inflammatory and blood gas markers of COVID-19 delirium compared to non-COVID-19 delirium: a cross-sectional study | journal = Aging & Mental Health | volume = 26 | issue = 10 | pages = 2054–2061 | date = October 2022 | pmid = 34651536 | doi = 10.1080/13607863.2021.1989375 | s2cid = 238990849 | doi-access = free }}</ref>) and [[urinary tract infection]]s
** [[Iatrogenesis|Iatrogenic]] complications
** [[Hypoxia (medical)|Hypoxia]], [[Hypercapnia|hypercapnea]], [[anemia]]
** Poor nutritional status, dehydration, electrolyte imbalances, [[hypoglycemia]]
** [[Shock (circulatory)|Shock]], [[Myocardial infarction|heart attacks]], [[heart failure]]
** Metabolic derangements (e.g. [[SIADH]], [[Addison's disease]], [[hyperthyroidism]])
** Chronic/terminal illness (e.g. cancer)
** Post-traumatic event (e.g. fall, fracture)
** [[Mercury poisoning]] (e.g. [[erethism]])
* Major surgery (e.g. cardiac, orthopedic, vascular surgery)