Altered Mental Status

  • Author: Tom Morrissey, MD, University of Florida, Jacksonville, Florida
  • Editor: David A. Wald, DO, Temple University School of Medicine, Philadelphia, Pennsylvania
  • Last Updated: 2008


Its 3 am on Saturday. The nurse lets you know about the new patient in room 19 that was just sent over from the local nursing home with a chief complaint of "AMS". She's 87 years old, bed-bound and minimally verbal. Her chart shows a history of multi-infarct dementia, schizoaffective disorder, alcoholism and probable narcotic dependence. Though you're way too professional to ever say this out loud, in the back of your mind you're thinking, "how on earth would anyone know?"

It's not a facetious question. Diagnosing a patient with a change in mental status can be a daunting challenge in the emergency department. Some presentations are relatively straight forward; a patient who is postictal after a seizure or a diabetic patient who is hypoglycemic. At times the clinical picture is more subtle and not easily identified. Enlisting historical data from multiple sources and maintaining a high index of suspicion is necessary to detect the behavioral marker of potentially catastrophic pathology. Altered mental status (AMS) is not a disease: it is a symptom. Causes run the gamut from easily reversible (hypoglycemia) to permanent (stroke) and from the relatively benign (alcohol intoxication) to life threatening (meningitis or encephalitis). The differential is enormous. Developing a structured and systematic approach to these cases will help you develop and streamline the diagnostic work up and management of these patients.


Upon completion of this self-study module, you should be able to:

  • Recognize the importance of historical factors in diagnosing causes of AMS
  • Identify dementia, delirium and psychosis as the three most common classifications of AMS
  • Articulate a differential diagnosis of AMS based on H&P findings
  • Construct an approach to the diagnostic workup and management of a patient with AMS
  • Describe initial management of many causes of AMS
  • Discuss the disposition of a patient with AMS

Initial Actions and Primary Survey

All emergency department patients require an initial assessment for immediate threats. The “ABCDE approach” also provides a good opportunity to check for quickly reversible causes of AMS. Ideally this should happen as the patient is being placed on a monitor and IV access is being established.

  1. Check to see that the airway is open and protected. Are there secretions or vomit that needs to be suctioned? Open the airway, check pulse-oxymetry and provide supplemental oxygen if needed. Hypoxia is a potentially reversible cause of AMS.
  2. Assess breathing. Inadequate ventilation will lead to elevated levels of CO2 (respiratory acidosis) and can cause AMS. Bag-valve-mask ventilation should be provided until adequate ventilation can be restored. In a patient with AMS and a depressed respiratory status, consider narcotic overdose as a possible cause.
  3. Assess circulatory status. Can you feel good distal pulses? Is the blood pressure very high or low? What is the cardiac rhythm? Hypoperfusion starves the brain of oxygen and glucose and leads to AMS. Nonperfusing rhythms require immediate CPR and ACLS. Hypotension should prompt IV fluid bolus and an immediate search for the cause.
  4. Check for neurologic disability. Use Glasgow Coma Score (GCS) or Alert Verbal painful unresponsive (AVPU) scale (see below) for a quick assessment of level of consciousness. Look for seizure activity. Are the pupils equal and reactive? Pay attention to spontaneous movements. Lack of movement on one side of the body night indicate stroke while lack of movement below a certain level of the body could indicate spinal cord injury. If there is any suspicion of trauma the cervical spine should be stabilized.
  5. Expose (fully undress) and perform a rapid head to toe look for signs of trauma, transdermal drug patches, dialysis access, infectious sources (such as catheters) or petechiae.

As you proceed through the above steps of initial stabilization, keep in mind rapidly reversible causes for the AMS. Hypoglycemia and narcotic overdose are very common causes of AMS and can easily be managed with dextrose and naloxone respectively. At a minimum, all AMS patients deserve:

  • Assessment of the ABC's
  • Cardiac monitoring and pulse oximetry
  • Supplemental oxygen if hyperemic
  • Bedside glucose testing
  • Intravenous access
  • Evaluation for signs of trauma and consider c-spine stabilization
  • Consider naloxone administration if narcotic overdose is suspected

Differential Diagnosis

The differential diagnosis of AMS is exhausting. In addition history and physical exam findings, ones differential will be influenced by factors such as the patient's age, medical co-morbidities, and perhaps even time of year (winter – carbon monoxide toxicity in cold weather climate zones). Like many complaints or presentations, it is difficult to list all possible causes. In the case of a patient with an AMS, your differential diagnosis can develop along a number of different pathways. The below table may assist you as you develop your differential. This table organizes causes of AMS occurring as a result of a structural lesion or primary CNS dysfunction, toxic, metabolic or infectious insults.

Differential Diagnosis for AMS by system
Primary CNS/Structural
  • Tumors
    • Primary
    • Metastatic
  • Hemorrhage
    • Spontaneous
    • Traumatic
  • Edema
    • HTN enceph
    • Obstructive hydrocephalus
    • Tumor
  • Seizure
    • Post-ictal state
    • Todd's paralysis
  • Dementia
    • Degenerative
    • Multi-infarct
  • Hypo/hyper
    • glycemia
    • natremia
    • calcemia
    • thyroid
    • thermia
  • Hypercarbia
  • Hypoxemia
  • Medication effects
    • HTN
    • Steroids
    • Sedatives
    • Analgesics
    • Sleep aids
    • Anticholinergics
    • Polypharmacy
  • Alcohols
    • ETOH
    • Methanol/ethylene glycol
  • Illicit drugs
  • Withdrawal
    • Alcohol
    • Benzodiazepine
    • Narcotic
  • Primary CNS
    • Meningitis
    • Encephalitis
    • Abscesses
  • Other site of infection
    • UTI
    • Pneumonia
    • Skin/decub ulcer
    • Intra-abdominal
    • Viral syndrome
  • Hypoperfusion states
    • Cardiogenic
    • Hypovolemic
    • Hemorrhagic
    • Distributive
  • Complicated migraine
  • Psychiatric dosorder
    • Acute
    • Chronic
  • Sundown/ICU psychosis

Alternatively, a mnemonic that is commonly used to help generate a differential diagnosis of AMS is:

EEpilepsy, Electrolytes, and Encephalopathy
OOpiates and Oxygen
TTrauma and Temperature
PPoisons and Psychogenic
SShock, Stroke, Subarachnoid Hemorrhage and Space-Occupying Lesion

Classic Presentation

Unfortunately, there is no classic presentation for a patient with AMS. The terms, “Altered mental status” and “altered level of consciousness” (ALOC) are common acronyms, but are vague nondescript terms. The same can be said about terms such as lethargy or obtundation. Both represent some level of decreased consciousness but are more subjective descriptors than true objective findings. The “AMS” label may be applied to a patient who is postictal or perhaps a patient who has dementia. Because the varied presentations that can range from global CNS depression to confusion, agitation, etc., it is important to be clear about terminology and how we describe a patient's mental status. Three common broad classifications of AMS include delirium, dementia and psychosis. It important to keep these in mind as you assess your patient because they have very different causes, treatments and dispositions. The table below describes fundamental differences between these 3 entities. History and physical exam are almost always enough to classify your patient into one of the categories.

Categorizing Causes of AMS
Rapid onsetSlow onsetVariable onset
Fluctuating courseProgressive courseVariable course
Often abnormal vital signsUsually normal vital signsUsually normal vital signs
Altered level of consciousnessNormal level of consciousnessVariable level of consciousness
Visual hallucinations (related to external stimuli)Rare hallucinationsAuditory hallucinations (related to internal stimuli)
Physical exam often abnormalPhysical exam often normalPhysical exam often normal
Prognosis poor if cause not txPrognosis progressivePrognosis variable
Organic (myriad) underlying causeOrganic (degenerative) underlying causeFunctional underlying cause


Typically, dementia is a slow progressively degenerative process that is managed by primary care physicians rather than in the ED. Sometimes families bring a dementia patient in to the ED and the true “emergency” is that they are no longer able to care for the patient at home. Admission may be necessary for safety, social assessment and placement. Psychosis is generally managed by psychiatry services rather than the ED. Decompensation of psychiatric illness, however, may lead to dangerous situations for the patient or others. Crisis intervention in these situations represents a true emergency. Management of these situations can be one of the most difficult challenges emergency physicians face.


Delirium represents a true medical emergency. Normal consciousness requires both arousal and cognition. Arousal is mediated primarily by brainstem nuclei (reticular activating system) while cognition and organized thought is dependent on cortical functioning. Delirium is brain dysfunction resulting in alterations of both level of arousal and thought content. Isolated structural lesions are incredibly unlikely to involve brainstem and bilateral cortical structures and still leave the patient alive. Delirium is almost always caused by an underlying medical problem that has toxic or metabolic affects on the brain. Screening for delirium in all altered patients is critical because it may lead us down our diagnostic pathway. Recognizing delirium gives us a chance to avert disaster. Delirium has a very poor prognosis unless the underlying cause is recognized and remedied.


Functional (psychiatric) changes in behavior (like depression or fugue states) can be difficult to distinguish from organic causes of behavioral changes. Much of “medical clearance for psychiatry” deals with this conundrum. When in doubt, assume a medical (organic) etiology until it can be clearly ruled out.

Neurologic causes

Some focal neurological deficits can be mistaken for alterations in consciousness. Dysarthrias and aphasias (receptive, motor or mixed), spatial neglect syndromes, even hemianopsias and hemiparesis can be mistaken as confusion if not looked at closely.

Detailed History and Physical Exam


Patients with an AMS are, by definition, difficult to derive a comprehensive and detailed history from. Family, friends, caretakers, nursing home workers, witnesses are all invaluable sources of information. Make the effort to contact them to ascertain the nature of the change in mental status.

  • Can you tell me what you see different about your grandmother?What's she like on a good day? Does she cook/do laundry for herself? Can she get around the house on her own? Can she be left alone? Can she hold a conversation about current events?
  • Can you describe how she is different?Is she more quiet/agitated? Is she confused or forgetful? Is she hallucinating?
  • When did this change start? Did this change come on suddenly or gradual? Is it continuous or does it wax and wane (identify pattern)? Has it ever happened before (previous diagnosis)? Have there been any changes in her medicines recently (polypharmacy)?
  • What do you think might have caused this?Does she administer her own medicines? Is she prone to falls? Could she have gotten into someone else's medicines or household poisons? Does she have parents or siblings with similar conditions? Have there been any significant stressful events lately such as hospitalization, loss of a love one or moving to an unfamiliar environment?
  • Screen for delirium:Many screening tools are available. One of the simplest is the confusion assessment method:CAM-ICU. If the patient has an acute or fluctuating course, evidence of inattention and either disorganized thinking or an altered level of consciousness (elevated or decreased), they have a very high likelihood of having delirium.

Many medical conditions manifest as AMS when decompensated. Look for a history of:

  • diabetes (DKA, HHNK),
  • hypertension (hypertensive encephalopathy or medication overdose)
  • endocrine disease (thyroid, Addisons)
  • renal failure
  • cancer (paraneoplastic syndromes, Na+, Ca++)
  • dementia
  • cardiovascular and cerebrovascular disease
  • seizure (atypical?)
  • psychiatric issues

Medication effects are also very common causes of AMS in the elderly. A detailed review of medications (including nonprescription, health supplements, home remedies) is critical. Has the patient recently started or stopped any medications?


A detailed head to toe physical exam will often yield clues as to the cause. Fully undress and examine the entire patient. Don't leave a square inch unexamined (you'd be amazed where you'll find a fentanyl patch sometimes). Pay particular attention to:

Glasgow Coma Scale

4 - Spont

3 - Loud voice

2 - To Pain

1 - None

5 - Oriented

4 - Confused

3 - Inappropriate words

2 - Incomprehensible sounds

1 - No Sounds

6 - Obeys

5 - Localizes to pain

4 - Withdraws to pain

3 - Abnormal flexion posturing

2 - Abnormal extension posturing

1 - None

GCS score was designed to predict outcome after head trauma. Although we frequently use it to help decide who needs aggressive management (“less that eight, intubate!”), it has never been validated for that purpose. Further, there is often a 1-2 point disagreement between individual evaluators. It is, however, a quick useful way to communicate overall level of arousal.

  • Vital signs
    • Does the patient have a fever?
    • Is the patient bradycardic or tacycardic?
    • Is the patient bradypneic or tachypneic?
    • Is the patient hypotensive or severely hypertensive?
  • Neurologic status
    • Level of alertness
    • GCS score (see above) or AVPU scale (A=alert, V=responds to verbal stimuli, P=responds to painful stimuli, U=unresponsive). A verbal description is helpful
    • How difficult is it to keep the patient awake?
  • Content of thought and speech
    • Does the patient stay focused?
    • Is their speech tangential?
    • Is the patient appropriately oriented?
    • Does the patient keep asking the same questions over and over (perseveration)?
    • Are they reacting to internal stimuli?
  • Assess for focal motor findings
    • Is there weakness or pronator drift?
    • Cranial nerve exam (especially pupils)
    • Remember, the brainstem is where isolated structural or ischemic lesions can cause decreased arousal. Decreased level of consciousness with cranial nerve findings is a brainstem lesion until proven otherwise.
    • Evaluate for tremulousness or abnormal reflexes
    • Common in withdrawal states or metabolic derangements
  • Cardiovascular exam
    • Are there arrhythmias (a-fib) that predispose to embolic strokes?
    • Is there a murmur? endocarditis?
    • Is there evidence of good peripheral circulation?
    • Are there pulmonary findings that indicate pneumonia (sepsis) or pulmonary edema (hypoxia)?
    • Are there bruits over the carotid arteries?
  • Abdominal exam
    • Is there ascites, caput medusa, liver enlargement or tenderness (hepatic encephalopathy)?
    • Is the abdomen tender (appendicitis, intussusception, abdominal sepsis source, mesenteric ischemia)?
  • Genitourinary and rectal exam
    • Is the patient making urine (uremic encephalopathy)?
    • Are there signs or urinary, vaginal, prostatic or perineal infection?
    • Is there melena or blood in the stool?
  • Skin, extremity, musculoskeletal exam
    • Are there petechiae (meningococcemia)?
    • Is there a dialysis graft (uremic encephalopathy)?
    • Are there track marks from injection drug abuse?
    • Are there transdermal drug patches?
    • Is the skin jaundiced (hepatic encephalopathy)?
    • Is there nuchal rigidity or meningismus (CNS infection)?
    • Are there signs of trauma (raccoon's eyes, Battle ‘s sign, hemotympanum)?
    • Are there infectious sources noted (decubitus ulcers, cellulitis, abscesses)?
    • Are there masses or lymphadenopathy that might indicate cancer (paraneoplastic syndromes)?

History and physical exam findings are usually enough to help you categorize the change in mental status as delirium, dementia or psychosis. Further testing should be ordered as below to help narrow the differential within each of these categories of AMS.

Diagnostic Testing

Generally, diagnostic testing is used to rule in or rule out items on your differential diagnosis and should not be ordered in a “shot-gun” fashion. In the case of a patient with an undifferentiated AMS presentation, liberal use of diagnostic studies is frequently necessary because of the breadth of the differential and the high stakes involved in delaying appropriate treatment. It is helpful to think of the main categories of causes for AMS and use diagnostic testing if any of these categories cannot be ruled out by H&P alone.

  • Metabolic or Endocrine causes
    • Rapid glucose
    • Serum electrolytes (Na+, Ca+)
    • ABG or VBG (with co-oxymetry for carboxy- or met-hemoglobinemia)
    • BUN/Creatinine
    • Thyroid function tests
    • Ammonia level
    • Serum cortisol level
    • Toxic or medication causes
  • Levels of medications (anticonvulsants, digoxin, theophylline, lithium, etc.)
    • Drug screen (benzodiazepines, opioids, barbiturates, etc.)
    • Alcohol level
    • Serum osmolality (toxic alcohols)
    • Infectious causes
  • CBC with differential
  • Urinalysis and culture
  • Blood cultures
  • Chest X-ray
  • Lumbar puncture (with opening pressure)
  • Always CT first if you suspect increased ICP.
  • Traumatic causes
  • Head CT/ cervical spine CT
  • Neurologic causes
    • Head CT (usually start without contrast for trauma or CVA)
    • MRI (if brainstem/posterior fossa pathology suspected)
    • EEG (if non-convulsive status epileptics suspected)
  • Hemodynamic instability causes
    • ECG
    • Cardiac enzymes (silent MI)
    • Echocardiogram
    • Carotid/vertebral artery ultrasound

How do I make the diagnosis?

Be careful using Occam's razor in diagnosing the cause of AMS. We would all like to find a single unifying cause for what ails our patients, and frequently the simplest, most straightforward answer is the correct one. Mental status changes, however, are often multifactorial. Diagnosis is never assured until abnormalities have been recognized, remedied, and the patient has returned to their normal mental status. Sometimes this is quick and clear (D50 reversing hypoglycemia or naloxone reversing a heroin overdose), but often it takes hours or days to see the fruits of our labor. Initial diagnostic maneuvers are primarily determined by the history and physical exam findings. These clues will allow you to build a working differential diagnosis based on the major categories that cause alterations in mental status. Often presumptive treatment is begun at this point (see below). Diagnostic imaging and laboratory tests are ordered to narrow down or confirm the differential diagnosis. Remember, in emergency medicine, diagnosis and treatment is a dynamic process. As treatment is initiated it is important to frequently reassess the patient. How are they responding to the interventions? Their response is often what clinches the diagnosis or reminds us to look in a different direction. In some cases, the diagnosis will not be definitively made in the ED. Dementia requires neuropsychiatric testing beyond our scope of practice. Psychiatric disorders cannot be adequately diagnosed and treated in a single ED visit. The physicians who can make these diagnoses do rely on us to rule out other organic causes of behavioral changes. Thus, our negative work-ups can be just as important as our positive ones. Be very careful about clearing a patient for psychiatric evaluation without close investigation for organic causes. Any abnormal vital signs, physical findings or diagnostic tests should be viewed as red flags. When in doubt, err on the side of caution.


Beyond interventions required for the immediate life threats such as impending cardiopulmonary collapse, treatment should be geared towards correcting / treating the underlying pathology. This may include;

  • Dextrose for hypoglycemia
  • Naloxone for opioid toxicity
  • Supportive care and sedation for agitated withdrawal states
  • Intravenous fluids for dehydration, hypovolemia, hypotension or hyperosmolar states such as HHNS or hypernatremia
  • Empiric antibiotics for suspected meningitis, urosepsis, pneumonia, etc.
  • Rewarming or aggressive cooling for temperature extremes
  • Fomepazole, pyridoxine, digoxin-fab fragments or other antidotes for specific toxins
  • Controlled reduction of blood pressure with nitroprusside, labetolol or fenoldepam for hypertensive encephalopathy
  • Hypertonic saline for profound hyponatremia with seizures or AMS
  • Glucocorticoids for metastatic CNS lesions with vasogenic edema
  • Consider thiamine for suspected Wernicke's encephalopathy


The majority of patients with an AMS will require hospitalization. Sometimes, however, patients with acute alterations in consciousness that are easily reversed and observed to be stable in the emergency department can safely be discharged home.  Classic examples of this subset of patients includes:

  • Seizure-Patients with known seizure disorders found to have low anticonvulsant levels may be discharged if medications can be loaded and appropriate safe follow-up can be assured.
  • Hypoglycemia- Diabetic patients found to be transiently hypoglycemic and improve with dextrose may be discharged if a clear reason can be found, they are not on long acting agents, and appropriate supervision and safe follow-up can be assured.
  • Narcotic overdose-When properly treated and observed in the emergency department, these patient may be safely discharged home.

Disposition of the patient presenting with AMS is highly variable and dependent on many factors:

  • How sick is the patient?
  • the cause identifiable and easily reversed?
  • Has the cause been fixed?
  • Did the patient return to normal?
  • Is the situation likely to return?
  • If it does return, is there adequate social support to recognize it and bring the patient in for medical care?

The decision to admit the patient to an ICU setting as opposed to the hospital ward may be based on hemodynamic stability, etiology of the AMS, expected course, need for close monitoring, airway management issues and institutional resources. What if a patient doesn't recognize their need for treatment and wants to leave the hospital? Patients with mild alterations in mental status frequently get frustrated and want to leave the hospital. This poses a special problem for emergency physicians. Often we are not able to quickly ascertain the underlying cause for the change in behavior. We recognize the potential dangers in this presenting complaint, but also want to respect patient autonomy and abide by their decisions. Does the patient have medical decision making capacity? Our responsibility as healthcare providers often revolves around the determination of capacity: specifically, does the patient have the mental capacity to understand the ramifications of refusing care and leaving the hospital against medical advice. The patient will need to demonstrate that they understand both the risk of leaving against advice and the benefit of staying. Solicit the help of family and friends. They may be able to convince the patient to stay for treatment. When in doubt err on the side of caution. Our profession gives us some protection regarding hospitalizing patients against their will, when we think it is medically necessary and justified. Make the effort to explain the situation to family members and enlist their help. Clearly document the reasons behind your thought processes and actions on the chart.

Pearls and Pitfalls

  • Failure to recognize subtle changes in behavior as significant. Seek historical witnesses and LISTEN to them!
  • Failure to recognize AMS, especially delirium as a symptom of serious medical illness.
  • Failure to look for and treat easily remediable causes.
  • Allowing an AMS patient to sign himself out “against medical advice” without talking to family and clearly documenting that the patient has medical decision making capacity.

References/Further Reading

  • Starkman S and Wright S. Altered Mental Status. In: Emergency Medicine. An Approach to Clinical Problem Solving. Hamilton GC, Sanders AB, Strange GR and Trott AT Eds. WB Saunders and Co. 2003. 517-534.
  • American College of Emergency Physicians: Clinical policy for the initial approach to patients presenting with altered mental status. Ann Emerg Med. 1999;33:251-280.
  • Ely EW, Inouye SK, Bernard DG, et al. Delirium in mechanically ventilated patients: validity and reliability of the confusion assessment method for the intensive care unit (CAM-ICU). JAMA. 2001;286:2703-2010.
  • Han JH, Zimmerman EE, Cutler N, et al. Delirium in older emergency department patients: recognition, risk factors, and psychomotor subtypes. Acad Emerg Med. 2009;16:193-200.
  • Koita J, Riggio S and Jagoda A. The mental status examination in emergency practice. Emerg Med Clin N Am. 2010;28:439-451.
  • Kanich W, Brady VJ, Huff JS, et al. Altered mental status: evaluation and etiology in the ED. Am J Emerg Med. 2002;20:613-617.
  • Simon JR MD PhD. Refusal of care: the physician-patient relationship and decision making capacity. Ann Emerg Med. 2007;50(4):456-461.