Altered Mental Status (AMS)

How altered mental status is classified

Consciousness has two parts: arousal (being awake) and content (awareness, attention and thought). AMS can affect either:

• Reduced arousal: lethargy, obtundation, stupor and coma.
• Disordered content with arousal preserved: confusion and delirium, which is an acute, fluctuating disturbance in attention and awareness. Delirium may be hyperactive (agitated, restless), hypoactive (quiet, sleepy, withdrawn) or mixed. Hypoactive delirium is the most common in older adults and the most often missed.

Glasgow Coma Scale

The GCS scores three responses. The total ranges from 3 (no response) to 15 (fully alert).

A GCS of 13 to 15 is mild impairment, 9 to 12 moderate, and 8 or less severe. Paramedics also use the simpler AVPU scale: Alert, responds to Voice, responds to Pain, Unresponsive.

Causes

Primary brain causes

These often produce focal signs (weakness of one side, unequal pupils, speech loss):

• Stroke, brain hemorrhage, subdural hematoma
• Seizures, including non-convulsive status epilepticus and the post-seizure (postictal) state
• Meningitis, encephalitis and brain abscess
• Brain tumors, hydrocephalus and raised intracranial pressure
• Traumatic brain injury

Body-wide (secondary) causes

These usually cause non-focal confusion or drowsiness:

• Metabolic: hypoglycemia, hyperglycemic states, low or high sodium, high calcium, liver failure (hepatic encephalopathy), kidney failure (uremia), thyroid disorders, adrenal insufficiency. See metabolic encephalopathy.
• Hypoxia and hypercapnia: low oxygen or retained carbon dioxide from COPD, pneumonia, heart failure, carbon monoxide.
• Infection: sepsis, pneumonia and urinary infection, especially in older adults.
• Toxins and drugs: alcohol, opioids, benzodiazepines, anticholinergics, antidepressant overdose, serotonin syndrome, withdrawal states.
• Nutritional: thiamine deficiency causing Wernicke encephalopathy, especially with alcohol use or malnutrition.
• Circulatory: shock, severe dehydration, very high blood pressure (hypertensive encephalopathy).
• Temperature: hypothermia and heat stroke.

In older adults, several minor factors often combine: a mild infection, a new medicine, dehydration, poor sleep and sensory loss.

Diagnosis

Immediate assessment

1. ABCs: airway, breathing, circulation. Oxygen if levels are low.
2. Point-of-care blood glucose, because hypoglycemia is quick to treat and can mimic stroke.
3. Vital signs: temperature, heart rate, blood pressure, breathing rate, oxygen saturation.
4. Neurological exam: GCS, pupils, eye movements, limb strength, neck stiffness.
5. Stroke pathway if focal signs began within the treatment window.
6. Collateral history from family or caregivers: baseline function, timing, medicines, alcohol, falls, recent illness.

Investigations

• Blood tests: electrolytes including sodium and calcium, kidney and liver function, complete blood count, glucose, blood gases, ammonia (selected cases), thyroid function, drug and alcohol levels, blood cultures
• Urine test and chest X-ray for infection
• ECG for arrhythmias and drug toxicity
• CT scan of the head for bleeding, stroke or mass, especially with focal signs, head injury or anticoagulant use
• Lumbar puncture for suspected meningitis, encephalitis or subarachnoid hemorrhage
• EEG for possible non-convulsive seizures
• MRI for subtle strokes, encephalitis or Wernicke changes

Screening for delirium

Tools such as the Confusion Assessment Method (CAM) and the 4AT are used at the bedside. Delirium is diagnosed when there is an acute onset and fluctuating course, inattention, and either disorganized thinking or an altered level of consciousness.

Delirium vs dementia

People with dementia are at much higher risk of delirium, and a sudden worsening in someone with dementia should be treated as possible delirium.

Treatment

Treatment focuses on the cause:

• Glucose for hypoglycemia, and IV thiamine before glucose in people at risk of Wernicke encephalopathy
• Naloxone for suspected opioid overdose
• Antibiotics and fluids for sepsis or meningitis, started quickly
• Clot-busting treatment or clot retrieval for eligible ischemic strokes, and neurosurgery for some bleeds
• Correcting sodium slowly, because rapid correction can damage the brainstem
• Lactulose and treating triggers in hepatic encephalopathy
• Stopping or reducing culprit medicines

Supportive care for delirium

• reorientation with clocks, calendars and familiar people
• glasses and hearing aids in place
• regular fluids, nutrition, bowel and bladder care
• normal sleep-wake routines and early mobility
• avoiding restraints and sedatives where possible. Low-dose antipsychotics are reserved for severe distress or danger

Outlook

Recovery depends on the cause and how quickly it is treated. Hypoglycemia and opioid toxicity can resolve within minutes. Metabolic and infectious causes usually clear over days. Delirium in older adults can last days to weeks and is linked with longer hospital stays, falls and a higher risk of later cognitive decline, which is why prevention matters. Structural brain injuries may leave lasting deficits.

Frequently asked questions

What does AMS mean in medical terms?

AMS stands for altered mental status, an acute change in a person's level of consciousness, awareness, orientation or behavior. It is a description of what the clinician sees, not a diagnosis, and it prompts a search for the underlying cause.

What is the workup for altered mental status?

It starts with airway, breathing, circulation and an immediate blood sugar check. Then come vital signs, a neurological exam, blood and urine tests, an ECG, and often a CT scan of the head. Lumbar puncture, EEG and MRI are added depending on the suspected cause.

What does AEIOU TIPS stand for?

It is a memory aid for causes of altered mental status: Alcohol, Epilepsy/Electrolytes/Encephalopathy, Insulin, Oxygen/Opioids, Uremia, Trauma/Temperature, Infection, Psychiatric/Poisoning, Stroke/Shock.

Is altered mental status the same as delirium?

Not exactly. Delirium is one type of altered mental status, defined by an acute, fluctuating disturbance in attention and awareness. AMS is the broader term that also includes reduced consciousness such as stupor and coma.

How long does altered mental status last?

It depends on the cause. Low blood sugar or opioid effects can reverse within minutes once treated. Infection-related confusion often improves over days. Delirium in older adults may take weeks to resolve, and a minority have lasting memory or thinking changes.