Delirium is an acute confusional state that occurs in response to physiologic stress, most commonly from a medical illness. It is a clinical syndrome seen frequently in older adults, particularly in hospital settings, presenting in up to 30% of older adult inpatients and 70% of older adults in critical care units. Delirium prolongs hospital stays, is associated with functional decline, and results in increased rates of institutionalization and death. It is often missed clinically and as discussed later, can often be prevented.

Risk Factors

Predisposing factors

Include age over 80 years, prior history of delirium, male gender, immobility, sensory impairment, multiple medical co-morbidities, polypharmacy, and malnutrition. In addition, patients with mild cognitive impairment, dementia or other neurodegenerative disorders, cerebrovascular disease, or chronic substance abuse are also at increased risk.

Precipitating factors

Include conditions such as an acute illness, metabolic derangements, use of physical restraints, dehydration, pain, infection, urinary retention and fecal impaction. Delirium can also occur in the perioperative period in patients who have undergone surgery. In addition, delirium can result from changes in medication regimens and substance use/abuse. Medications commonly associated with delirium are shown in Table 1.

Diagnosis

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) defines delirium as

1. a disturbance in attention that
2. develops over a short period of time and
3. is accompanied by a disturbance in cognition. It adds that
4. these disturbances are not better explained by a pre-existing, established, or evolving neurocognitive disorder, and do not occur in the context of a severely reduced level of arousal such as coma. Also, that
5. there should also be evidence from history, physical exam, or lab testing that the disturbances are caused by a medical condition or exposure to a medication or toxin.

Note that newly diagnosed dementia can sometimes be confused with delirium. Table 2 lists key differences.

Delirium can have different clinical presentations. When patients have overt behavior disturbances and obvious confusion, hyperactive delirium is readily diagnosed. Most delirious older adults, however, present in a quiet, hypoactive state, and their delirium may be less evident on exam. With mixed delirium, patients often fluctuate between the two. Delirium assessment tools can help to identify hyperactive, hypoactive, and mixed types.

The Confusion Assessment Method (CAM) is a widely used, evidence based instrument for delirium diagnosis. It is well-validated with high sensitivity, specificity, and inter-rater reliability. The CAM has four components. To diagnose delirium, the first two must be present: (1) acute onset of changing or rapidly fluctuating mental status, and (2) inattention, along with at least one of the next two components (3) disorganized thinking and/or (4) altered level of consciousness (Table 3).

Prevention and Treatment of Delirium

Once delirium is diagnosed, treatment should be instituted immediately, as the duration of delirium is associated with increasing risks of long-term cognitive impairment.

Resolving underlying medical problems is the best intervention for treating delirium. Patients should be evaluated for treatable causes, such as the precipitating factors listed previously. Always review medications, especially any recently started. Further testing, including brain imaging, lumbar puncture, and/or EEG should follow if a treatable cause is not identified. Even after treating a causal condition, however, resolution of delirium may take weeks to months to resolve, and sometimes as long as a year.

Behavioral interventions (Table 4) can be effective not only for preventing delirium, but also for treating delirium once it has developed. Physical restraints can worsen symptoms and should be avoided.

Pharmacologic therapy is often used in the treatment of delirium, but its role and value depend on the clinical situation. Drug treatment may reduce agitation, but prolong delirium and cognitive decline. Hypoactive delirium is managed without medications by treating reversible medical conditions and instituting the interventions listed in Table 4.

Hyperactive delirium, on the other hand, can require emergency intervention to prevent patients from hurting themselves or others. Although no medications are FDA approved for treating delirium, antipsychotics can be used when no other measures are successful. While haloperidol has long been considered the drug of choice for hyperactive delirium and it can be administered by multiple routes (PO, IM, IV), recent data suggest that the newer antipsychotics (e.g., quetiapine risperidone, olanzapine) result in more rapid symptom improvement and are better tolerated by patients, including fewer extrapyramidal side effects. Benzodiazepines are indicated only for the treatment of delirium from alcohol or benzodiazepine withdrawal.

References and Resources

• Confusion Assessment Method Training Manual
• Girard TD, et al. Delirium as a predictor of long-term cognitive impairment in survivors of critical illness. Crit Care Med. 2010;38:1513-20
• Marcantonio, ER. Delirium in hospitalized older patients.  NEJM. 2017;337: 1456-66.
• Oh, ES, Fong, TG, Hshieh, TT, Inouye, SK.  Delirium in older persons-advances in diagnosis and treatment. JAMA. 2017; 318(: 1161-74.
• Inouye, DK, Westendorp, R, Saczynski, JS. Delirium in elderly people. The Lancet. 2014;383(9920):911-22.
• Kishi T, et al. Antipsychotic medications for the treatment of delirium: a systematic review and meta-analysis of randomised controlled trials. J Neurol Neurosurg Psychiatry 2016;87:767-774.
• Wong, CL, Holroyd-Leduc, J Simel, DL, et al.  Does this patient have delirium?: Value of bedside instruments.  JAMA. 2010;304: 779-86.

Interprofessional care improves the outcomes of older adults with complex health problems

Elder Care Editors: Editor-in-Chief: Barry D Weiss, MD;  Deputy Editor: Mindy Fain, MD

National Editorial Board:  Theodore M Johnson II, MD, MPH, Emory University; Jenny Jordan, PT, DPT, Sacred Heart Hospital, Spokane, WA;  Jane Marks, RN, MS, FNGNA, Johns Hopkins University; Josette Rivera, MD, University of California San Francisco; Jean Yudin, CRNP, University of Pennsylvania

 Interprofessional Associate Editors: Carleigh High, PT, DPT; David Coon, PhD; Marilyn Gilbert, MS, CHES; Jeannie Lee, PharmD, BCPS; Marisa Menchola, PhD;  Francisco Moreno, MD; Linnea Nagel, PA-C, MPAS; Lisa O’Neill, DBH, MPH; Floribella Redondo; Laura Vitkus, MPH, CHES

Published by: The University of Arizona, PO Box 245027, Tucson, AZ 85724-5027  |  (520) 626-5800  | https://uofazcenteronaging.co

 This project was supported by the Health Resources and Services Administration (HRSA) of the U.S. Department of Health and Human Services (HHS) under grant number U1QHP28721, Arizona Geriatrics Workforce Enhancement Program.  This information or content and conclusions are those of the author and should not be construed as the official position or policy of, nor should any endorsements be inferred by HRSA, HHS or the U.S. Government.