Delirium, Dementia, and Amnesia in Emergency Medicine Clinical Presentation

Updated: Sep 19, 2018
  • Author: Richard D Shin, MD, FACEP; Chief Editor: Gil Z Shlamovitz, MD, FACEP  more...
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Altered Mental Status (AMS) can evolve acutely with a rapidly fluctuating and usually transient course (delirium); or insidiously and inexorably over months or years with an intermittently or gradually worsening course chiefly involving loss of short-term memory (dementia).


Delirium presents with acute onset of impaired awareness, easy distractability, confusion, and disturbances of perception (eg, illusions, misinterpretations or visual hallucinations). Recent memory is usually deficient, and the patient is typically disoriented to time and place. Level of awareness may range from hypervigilant and agitated to obtunded, and abnormalities of congition and behavior may fluctuate dramatically over brief periods. Speech may be incoherent, pressured, nonsensical, perseverating, or rambling. Obtaining a reliable history from a delirious patient may be difficult or impossible. Patients with delirium have difficulty maintaining attention and/or shifting the focus of their attention.

For patients with delirium, attempt to obtain a current and past history from other sources, including prehospital workers, family or friends, and past medical records. Look specifically for street drug, alcohol, over-the-counter or prescribed medication use. Consider preexisting endocrine disorders. Inquire about recent activities that may have resulted in exposure to toxins or environmental injury. Ask about prior psychiatric illness, history of overdose and similar episodes of confusion in the past.

Delirium typically manifests with either of two patterns of psychomotor activity: hypoactive or hyperactive. Hypoactive delirium is characterized by stupor, psychomotor lentification and lethargy, and is the most frequent pattern in older adults. Conversely, hyperactive delirium is characterized by agitation, hypervigilance and hallucinations. [8]  


Dementia presents with a history of chronic, steady decline in short and, later, long-term memory and is associated with difficulties in social relationships, work, and activities of daily life. In contrast to delirium, the sensorium is usually clear. However, acute confusional states can be superimposed on an underlying dementing process. The diagnosis is usually known previously in a patient who presents to the ED with moderate-to-severe symptoms.

Earlier stages of dementia may present subtly, and patients may minimize or attempt to hide their impairments. Patients at this stage often have an associated depression. In addition, major depression alone can present as a dementia-like condition in elderly patients but is treatable and reversible. Dementia of relatively recent onset has a higher likelihood of a potentially reversible etiology. Take a careful history, looking for past or present drug or alcohol abuse, current medications, chronic or acute medical illnesses and psychiatric disorders to uncover a treatable or modifiable cause for the cognitive impairment.

Elderly patients with depressed mood, hopelessness, and suicidality may be suffering from "pseudodementia" (false dementia). When the depression is alleviated with treatment, the dementia-like condition resolves.

A history of a stuttering course of chronic memory loss may point to multi-infarct dementia, which is caused by repeated lacunar strokes. Treatment aimed at preventing future strokes may arrest further progression of the dementia. However, small strokes in specific areas of the brain may trigger the onset of progressive Alzheimer-type dementia



Any patient who presents with altered mental status (AMS) needs a complete physical examination, with particular attention to general appearance, vital signs, hydration status, evidence of physical trauma, and neurologic signs. The delirious or obtunded patient should be evaluated for pupillary, funduscopic, and extraocular abnormalities; nuchal rigidity; thyroid enlargement; and heart murmurs or rhythm disturbances. Other clues include a pulmonary examination that reveals wheezing, rales, or absent breath sounds; an abdominal examination that reveals hepatic or splenic enlargement; or a cutaneous examination that shows rashes, icterus, petechiae, ecchymoses, track marks, or cellulitis. Cellulitis in elderly persons often is hidden under clothing, particularly pants and socks. Checking these areas in patients with diabetes is critical. Any serious infection can lead to acute mental status changes.

General appearance (eg, unkempt and/or malnourished) may suggest the possibility of drug or alcohol abuse.

Look for track marks indicative of IV drug use.

Smell for alcohol, the musty odor of fetor hepaticus, or the fruity smell of ketoacidosis.

Icterus and asterixis point to liver failure with an elevation of the serum ammonia level.

Agitation and tremulousness suggest sedative drug or alcohol withdrawal.

Close attention to vital signs is essential and easy to overlook in the setting of extreme behavioral difficulties in a delirious patient. It is unusual for a patient with acute delirium to present to the ED with normal vital signs.

Fever may point to infection, heat illness, thyroid storm, aspirin toxicity, or the extreme adrenergic overflow of certain drug overdoses and withdrawal syndromes (in particular, delirium tremens). Extreme hyperthermia (with pinpoint pupils) may be seen in pontine strokes. In patients with a rapid respiratory rate, consider diabetic ketoacidosis (ie, Kussmaul respiration), sepsis, stimulant drug intoxication, and aspirin overdose. In patients with a slow respiratory rate, consider narcotic overdose, CNS insult, or various sedative intoxications.

A rapid pulse rate is seen in patients with fever, sepsis, dehydration, thyroid storm, and various cardiac dysrhythmias and in overdoses of stimulants, anticholinergics, quinidine, theophylline, tricyclic antidepressants, or aspirin. Patients with a slow pulse rate may have elevated intracranial pressure, asphyxia, or complete heart block. Calcium channel blockers, digoxin, and beta-blockers also may produce altered mental status and bradycardia.

Blood pressure elevation is common in delirium because of resulting adrenergic overload.

In patients with acute altered mental status and severely elevated blood pressure, check the ocular fundi for arteriolar spasm, disc pallor, papilledema, flame hemorrhages, and exudates. These are all signs of malignant hypertension. Even with these changes, the patient may be alert and minimally symptomatic.

In pregnant or recently post-partum patients with a systolic blood pressure greater than 160 or a diastolic blood pressure greater than 90 mm Hg consider preeclampsia or eclampsia. 

In patients with hypertension and bradycardia, consider an elevated intracranial pressure.

With delirium and hypotension, the differential diagnosis includes dehydration, diabetic coma, hemorrhage due to trauma, aneurysmal rupture, gastrointestinal bleeding or sepsis. Consider adrenergic depletion secondary to cocaine; amphetamine; or tricyclic overdose, which usually responds to norepinephrine. Acute adrenal insufficieny, causing hypotension refractory to IV fluid challenge, should be considered in patients on long-term steroid therapy.

Pupillary dilation can be seen in anticholinergic overdose, stimulant use, and hallucinogen use. A common feature of diphenhydramine and other antihistamine overdoses is the behavior of picking at imaginary objects in the air. Early in the course, mydriasis may be absent but other signs of anti-cholinergic poisoning may be evident: dry mucous membranes, flushing, tachycardia, elevated body temperature, urinary retention and delirium.

Pupillary constriction can be seen in narcotic intoxication. Delirium can be associated with both acute intoxication and withdrawal, the latter of which can be precipitated with naloxone.

Serious head trauma is usually obvious. However, occult trauma may be discovered by findings of basilar skull fracture, such as hemotympanum, Battle sign (ie, mastoid area ecchymoses), raccoon eyes, or otorhinorrhea. The latter condition may be tested for by placing a drop of the draining blood on filter paper and then looking for a clear ring of cerebrospinal fluid (CSF). A funduscopic examination may show loss of venous pulsations in cases of early intracranial pressure (ICP) elevation or papilledema in severe ICP elevation. Pupillary inequality may be a late sign of uncal herniation.

At times, it may be difficult to distinguish between acute delirium, psychiatric crisis, or a chronic process with exacerbation such as dementia. It is safest to presume delirium until an alternative process can be proven through testing and/or clinical observation.

A brief bedside neurologic examination, including mental status testing, is an essential part of the workup of AMS when a rapidly treatable cause is not immediately apparent.

The Mini-Mental Status Examination (MMSE) is a formalized way of documenting the severity and nature of mental status changes. [9] The MMSE, as modified from Folstein, is outlined here. The maximum score per item is indicated in parentheses.

  • Orientation (5): What are the year, season, date, day, and month?

  • Orientation (5): Where are we (ie, state, county, town, hospital, and floor)?

  • Registration (3): Name 3 objects (ask the patient to repeat these 3 objects).

  • Attention and calculation (5): The serial 7 test awards 1 point for each correct answer. Stop after 5 answers. Spelling "world" backwards is optional.

  • Recall (3): Ask for the 3 objects (from Registration) to be repeated. One point is scored for each correctly recalled object.

  • Language (2): Name a pencil and a watch.

  • Repetition (1): Repeat the following: "No ifs, ands, or buts."

  • Complex commands (6): Follow a 3-stage command, such as "Take a paper in your right hand, fold it in half, and put it on the floor" (3 points). Next, read and follow these printed commands: "Close your eyes" (1 point); "Write a sentence" (1 point); and "Copy design" (1 point)

Instructions for administering the MMSE are as follows:

  • Orientation: Ask for the date. Specifically, ask for any omitted information. Give 1 point for each correct response.

  • Registration: Ask permission to test memory. Name 3 unrelated objects clearly and slowly about 1 second apart. After all 3 objects have been named, ask the patient to repeat them. The first repetition determines the score. Keep repeating the items, as many as 6 times, until the patient can repeat all 3 of them. (This step is also required for the Recall test.)

  • Attention and calculation: Ask the patient to begin with 100 and count backwards by 7s. Stop after 5 subtractions and score correct answers. If the patient cannot calculate, ask him or her to spell "world" backwards. The score is the number of letters in correct order.

  • Recall: Ask the patient to recall the 3 objects previously asked to remember (from Registration). Zero to 3 points may be scored.

  • Language: To test skills in naming objects, show a wristwatch and a pencil to the patient, and ask the patient to name each item. Zero to 2 points may be scored.

  • Repetition: Ask the patient to repeat a sentence. Allow 1 trial. Zero to 1 point may be scored.

  • Complex 3-stage command: Give the patient a piece of paper and repeat the command. Score 1 point for each portion of the command that is performed correctly.

  • Reading: Print clearly on a piece of paper in large letters the command "Close your eyes." Ask the patient to read and perform the command. Score 1 point if the eyes are closed.

  • Writing: Provide a blank piece of paper and ask the patient to write a sentence of his/her own choosing. It must contain a subject and a verb to be scored 1 point. Punctuation does not matter for the purpose of scoring.

  • Copying: On a clean piece of paper, draw intersecting pentagons, each side measuring 1 inch, and ask the patient to copy the figures exactly. All 10 angles must be present, and the 2 figures must intersect to score 1 point. Any rotation of the figures or tremor is ignored.

A score of less than 24 suggests the presence of delirium, dementia, or another problem affecting the patient's mental status and may indicate the need for further evaluation.

In addition, or as an alternative to the MMSE, correctly drawing the face of a clock (to include the circle, numbers, and hands) is a sensitive test of cognitive function. To perform this test, ask the patient to draw a clock with the hands at 8:20. Two or more errors significantly correlate with dementia. No errors rule against dementia.

The "Sweet 16" cognitive assessment tool offers a faster, simpler, and reasonably accurate alternative to the MMSE. [10] Advantages include the absence of a requirement for frail patients to manipulate pen and paper, freedom from props, and better accuracy across varying educational levels. The "Sweet 16" test is less selective (72% vs 89%) than the MMSE but is more sensitive (99% vs 87%). Therefore, a negative test result is highly accurate in ruling out dementia.

Other simple screening tests include asking the patient to spell "world" backwards or performing "serial 7's," which involves starting at the number 100 and subtracting 7 repeatedly in series (ie, 100, 93, 86, 79).



Delirium or acute altered mental status may be caused by the following:

  • Intoxication with a substance (eg, hallucinogens, alcohol, medications, toxins)

  • Polypharmacy, most often with psychoactive medications

  • Major surgery, orthopedic trauma, prolonged immobility, and “ICU psychosis”

  • Occult infection (eg, UTI, meningitis, encephalitis, neurosyphilis, sepsis)

  • Seizure disorder

  • Acute mania or other psychiatric etiology

  • Endocrine crisis (eg, thyroid, adrenal, diabetic)

  • High fever seen with infection or heat stroke

  • Renal failure

  • Liver failure

  • Neoplasia

  • Inflammation (eg, systemic lupus erythematosus)

  • Cerebral vascular accident (CVA)

  • Respiratory dysfunction (eg, hypoxia, hypercarbia)

  • Shock

  • Chronic neurological disorders such as dementia and Parkinson disease

  • “Sundowning” (see below)

In the elderly, the combined effects of visual and auditory impairments, dementia or other chronic brain dysfunction, medication side effects (particularly polypharmacy), and/or unfamiliar environment or nighttime darkness can lead to acute confusion or psychosis, which is known as sundowning. As the name implies, this condition usually occurs in the evening hours. Vitamin B-12 deficiency is a potential cause of sundowning as well as progressive but reversible dementia.

Head trauma, Korsakoff syndrome, transient global amnesia, and various dementing processes can cause amnesia. Head trauma can lead to transient amnesia with retrograde (events prior to injury) and anterograde (events following injury) features.

Postconcussive syndrome is a constellation of mental dullness, poor memory, depressed mood, and headaches that may follow head trauma, often lasting days to weeks, with full resolution in most cases. This may involve confusional state, but frank delirium is rare.

Transient global amnesia (TGA)  is seen in previously well, usually middle-aged patients who present with a sudden onset of confusion, amnesia, and anxious perseveration. [11] TGA can occur spontaneously or following minor trauma, exertion, or emotional stress. The amnesia usually lasts a few hours, with full recovery and rare recurrence.

Various causes have been proposed for TGA: most recently, transient ischemia-like attacks or perhaps ministrokes in the hippocampal or thalamic memory areas of the brain. Although the incidence of cerebrovascular risk factors in TGA is low, those patients with such risk factors (eg, hypertension, smoking, diabetes mellitus, hypercholesterolemia) should be considered for antiplatelet therapy. Although TGA may involve a transient ischemia to brain areas involved with memory (hippocampus, thalamus, mediobasilar temporal lobe), symptoms typically resolve more slowly than TIA. In addition, future risk of stroke and death are lower than in TIA. All patients with TGA should be admitted for monitoring and further workup.

Traveler’s amnesia is typically seen following a nap on an airplane after taking a short-acting hypnotic, such as alprazolam, triazolam, or zolpidem.

Korsakoff syndrome is caused by neuronal damage that results from thiamine deficiency in association with chronic alcohol abuse. It is usually preceded by an episode of Wernicke encephalitis (eg, ataxia, confusion, oculomotor palsy), typically precipitated by administration of glucose to a malnourished alcoholic without concomitant parenteral thiamine. Confabulation is a hallmark finding of Korsakoff syndrome (also called Korsakoff psychosis).

Dementia can occur primarily, or can be secondary to cerebrovascular disease, chronic CNS infection, CNS trauma, increased ICP (eg, neoplasia, mass effect, hydrocephalus), toxins, avitaminosis, autoimmune disease, and psychiatric illness.

Primary dementias include Alzheimer disease and frontotemporal dementia (FTD). AD accounts for up to 90% of all primary dementias and more than 50% of all dementing illnesses.

FTD is highly familial, presents at a younger age than Alzheimer disease, and is associated with profound personality changes, social incompetence, and stereotypical behaviors, yet with preserved visuospatial skills. The brain invariably shows a severe and asymmetric atrophy of the frontal and temporal lobes with only rare involvement of the parietal or occipital lobes associated with sparing of the posterior two thirds of the superior temporal gyrus. A thin, knife-edge appearance of the gyri is often seen secondary to the severe atrophy present in Pick disease, a subtype of FTD. The typical pattern of atrophy is often prominent enough to distinguish Pick disease from Alzheimer disease macroscopically.

Some forms of Alzheimer disease are thought to have a genetic or familial basis. This is particularly true of Alzheimer disease that begins at a relatively young age and follows a fulminant course.

Alzheimer-like dementia is seen in 40% of patients with Parkinson disease and in a very high percentage of patients with Down syndrome who live long enough to develop Alzheimer disease.

Cerebrovascular causes include lacunar stroke syndrome (multi-infarct dementia), thalamic stroke, and vasculitides as seen in systemic lupus erythematosus and other rheumatologic disorders.

Infectious causes of dementia include HIV, Creutzfeldt-Jakob disease, neurosyphilis, and the end stages of some cases of meningitis and encephalitis.

Traumatic causes of chronic dementia include anoxia, diffuse axonal injury (following a severe blow to the head), and dementia pugilistica ("punch drunk"), which results from repeated concussive trauma. A chronic subdural hematoma may present with a dementia-like syndrome.

Dementia, often in association with hostility and severe mood disorders can result from repeated sub-clinical head trauma or "mild concussions" over an extended period. Called chronic traumatic encephalopathy (CTE) , the condition is only confirmed after death via brain autopsy. [12, 13] Athletes involved in a variety of contact sports, most notably football and soccer (heading the ball), are at increased risk for CTE. [14] This is true even in the absence of any severe blows to the head. CTE has been diagnosed in young athletes playing contact sports for a relatively short period and dying of other causes (allowing for brain autopsy). This has led to reconsideration of the safety of football and soccer in children and teenagers. 

Toxins causing chronic organic brain syndrome include heavy metals (eg, lead in solder, ceramic glazes), organic chemical exposures, severe carbon monoxide poisoning, and chronic substance abuse.

Deficiencies of vitamin B-12 and folate can cause organic brain syndrome.

Autoimmune causes include systemic lupus erythematosus, giant cell arteritis, and sarcoidosis. Delirium has been associated with treatment or withdrawal of treatment of autoimmune diseases with high-dose steroids.

Psychiatric illnesses mimicking dementia include the pseudodementia of major depression in elderly persons and chronic schizophrenia (originally termed "dementia praecox"). Mania and hypomania as seen in bipolar disorder can be confused with delirium. In its severe form, “excited delirium” can be exacerbated by physical restraining and can lead to sudden cardiac death.

Other causes to consider include chronic endocrinopathies, Wilson disease (copper storage disease), and lipid storage diseases.