Psychiatric-Mental Health Nursing · Older Adults

Delirium

10 min read

Safety note: Educational overview only. Delirium is a medical urgency: nurses recognize acute change from baseline and escalate to the provider for evaluation of the underlying cause. Screening tools such as CAM require training and are applied per institutional policy; diagnosis, testing, and treatment are professional responsibilities. Restraint use follows strict policy only when safety demands. Educational draft only — screening tools, escalation protocols, restraint use, and reporting requirements vary by facility and jurisdiction; follow local policy and provider orders.

On this page 9 sections

In 30 seconds
Why this matters
The college version
Eli explains
Worked example
Key takeaway
Check yourself
Study tools
Sources & references

In 30 seconds

is an acute, fluctuating disturbance in attention and cognition caused by an underlying medical condition. It is one of the most important syndromes in older-adult care: common, dangerous, frequently missed — and often reversible when the cause is found and treated.

The classic picture is a hospitalized older adult who becomes confused, restless, and disoriented at night. But delirium has quieter forms: a patient who suddenly becomes withdrawn, sleepy, and hard to rouse () is just as delirious — and most often missed. Delirium is never "just confusion"; it signals that something is physically wrong and is managed as a medical urgency: recognize the change, report it, and let the team pursue the cause.

Why this matters

Delirium is common in hospitalized older adults — especially after surgery, in intensive care, and in people with dementia — and predicts worse outcomes: longer stays, functional decline, institutionalization, and higher mortality.
It is a medical emergency signal. Delirium is a symptom of an underlying problem — infection, medication effect, dehydration, metabolic disturbance — and that problem is the real target.
It is often missed or mislabeled: hypoactive delirium as depression or "just being tired," as dementia or "being difficult." Both mistakes delay treatment.
It is frequently preventable and often reversible. Nursing measures — orientation, mobilization, sleep protection, sensory aids — are core prevention, and prompt recognition shortens the episode.

The college version

Core Concepts

What delirium is

Delirium is a neurocognitive disorder with acute onset and , caused directly by a medical condition, substance intoxication or withdrawal, or medication effect. Defining features:

Acute onset: hours to a few days — sudden, not gradual.
Fluctuating course: symptoms come and go, often worse at night ("" pattern).
: the person cannot focus, follow a conversation, or keep track of what is happening.
Altered level of consciousness: from hypervigilant to drowsy to difficult to arouse.
Disorganized thinking: rambling or nonsensical speech, plus disturbed sleep-wake cycle, hallucinations, and emotional lability.

The three psychomotor subtypes

Hyperactive delirium: restless, agitated, pacing, pulling at lines, calling out — the most visible and most likely to be recognized.
Hypoactive delirium: quiet, withdrawn, slowed, sleepy, poorly engaged — the most often missed, with a worse prognosis partly because recognition is delayed.
Mixed delirium: alternates between the two.

The practical rule: any acute change in cognition or behavior in an older adult is delirium until proven otherwise — including the quiet patient who is "just tired."

Causes: the search for the underlying problem

Delirium has many causes, often several at once: infection (urinary tract infection, pneumonia — the classic culprits), medications (anticholinergics, sedatives, opioids; new drugs, dose changes, or polypharmacy; alcohol or sedative withdrawal), metabolic/electrolyte (dehydration, hyponatremia, renal or hepatic impairment, glucose or thyroid disturbance), hypoxia and cardiovascular (low oxygen, heart failure, shock), pain, constipation, and urinary retention, and sensory/environmental (unfamiliar surroundings, sleep deprivation, immobility, no glasses or hearing aids).

Because causes are multiple and interacting, the workup is interprofessional: the provider orders and interprets tests; the nurse gathers the history of onset, observes fluctuations, and monitors vital signs and intake/output.

Who is at risk

Risk factors include age 65 and older, pre-existing cognitive impairment, sensory impairment, severe illness, surgery (especially hip fracture and cardiac surgery), multiple medications, dehydration, malnutrition, immobility, sleep deprivation, and prior delirium. Frailty — the low-reserve state from earlier in this chapter — makes the brain vulnerable to small insults.

Delirium versus dementia versus depression

This three-way distinction is a classic exam and clinical question:

Delirium: acute onset (hours-days), fluctuating, inattention prominent, consciousness altered, caused by medical condition — potentially reversible.
Dementia: chronic, gradual onset (months-years), progressive, memory and other domains decline, consciousness clear until late stages — not reversible, though some causes are modifiable.
Depression: mood disturbance; cognitive complaints may mimic dementia (pseudodementia, see the Depression topic), but the person is usually attentive when engaged and can improve with treatment.

Delirium and dementia can coexist: dementia is a major risk factor for delirium, and delirium in a person with dementia is a change from baseline that must be recognized.

How we learned to recognize and prevent delirium: classic studies

Mid-20th-century psychiatrists Engel and Romano (1959) established delirium as a neurophysiologic syndrome, showing with serial EEGs that it involves diffuse slowing of brain electrical activity — a measurable correlate of the confused state, not a moral failing or nuisance behavior. They framed delirium as "a syndrome of cerebral insufficiency" with identifiable physiology.

Decades later, geriatrician Sharon Inouye and colleagues (1990s) identified delirium's major risk factors in hospitalized older adults and developed the — non-pharmacological interventions including orientation, early mobilization, sleep enhancement, and sensory aids. Trials showed delirium could be substantially prevented.

Methodological context matters: Engel and Romano's EEG studies were small physiological observations in selected patients; Inouye's risk-factor work used rigorous prospective cohorts and controlled evaluation of interventions, so its conclusions carry more weight. The historical thread — describe a syndrome, identify risk, test prevention — models how clinical knowledge advances. Both studies also carry an ethical lesson: delirium is a legitimate, serious medical condition, not the patient's fault.

The nurse's role: recognition, prevention, escalation

Know the baseline. "Is this normal for this person?" is the first question — ask family what the person was like before admission and document it.
Recognize acute change. Sudden inattention, fluctuation, new drowsiness or agitation, and disorientation are red flags; document onset and timing.
Escalate promptly. Report to the provider immediately and follow facility policy; the underlying cause needs evaluation (history, exam, labs, medication review) without delay.
Protect the patient while the team works. Orient with calendars and familiar faces, mobilize early, protect sleep, ensure glasses and hearing aids, manage pain and fluids, and avoid restraints whenever possible — restraints worsen delirium and are used only per strict policy when safety demands.
Do not blame or dismiss. Delirium is not willful, not "acting out," and not "just old age"; calm, person-centered communication reduces distress.

Common Confusions

Do not confuse	With	Difference
Delirium	Dementia	Acute onset, fluctuating, attention-based, potentially reversible vs. gradual, progressive, memory-based, irreversible — though they coexist
Delirium	Depression	Delirium has acute onset with altered consciousness/inattention; depression is a mood disorder that can mimic dementia (pseudodementia) but attention often improves with engagement
Hypoactive delirium	"Just tired" or depression	The quiet form of delirium is a medical signal, not fatigue — check for acute change and report
Hyperactive delirium	"Being difficult" or anxiety	Agitation from delirium reflects brain dysfunction from a medical cause — it is not willful behavior
"Sundowning" at night	Normal evening tiredness	Worsening confusion at night is a delirium pattern and a change to document, not to accept
Restraining an agitated patient	Preventing harm safely	Restraints worsen delirium and are used only per strict policy when safety demands; non-drug measures come first
Confusion as a diagnosis	Confusion as a symptom	Delirium is a symptom of an underlying medical condition — the cause is the target
Any nurse diagnosing delirium	Recognizing and escalating	Structured tools like CAM require training; nurses recognize acute change and report so qualified clinicians evaluate

Eli explains

The same idea, in plain words

Explain it like I’m 10

Delirium is like a sudden "fog" in the brain that comes from the body being sick — for example, an infection or a bad reaction to medicine. The person gets confused very quickly, and the confusion comes and goes. It is a serious warning sign, like a fire alarm: the nurse tells the care team right away so they can find and fix what is making the person sick.

Worked example

Mr. Patel, 79, with mild dementia, is admitted with a hip fracture after a fall at home. On day two after surgery, the nurse notices he is not himself: he answers slowly, his eyes are half-closed, and he barely picks at his tray — his daughter had said he "always talks your ear off." He is not agitated or calling out. It would be easy to say he is "just tired after surgery."

The nurse does not settle for that. She knows hypoactive delirium is the missed form, so she checks: vital signs show a slightly elevated temperature and fast pulse; simple attention questions lose him mid-sentence; the chart shows a new pain medication started the night before and little urine output since surgery. She documents the acute change from baseline, flags it in handoff, and reports to the provider promptly.

The provider evaluates and finds a urinary tract infection plus a sedating medication effect. The medication is adjusted, fluids and antibiotics begin, and the nurse adds prevention: his daughter brings his glasses, the blinds open during the day, he is helped to the chair twice daily, and sleep is protected at night. Within two days, Mr. Patel is back to talking — the difference between "just tired" and treated delirium was recognition of an acute change from baseline plus prompt escalation.

Key takeaways

Delirium = acute onset + fluctuating course + inattention + altered consciousness + underlying medical cause.
Three subtypes: hyperactive (agitated — visible), hypoactive (withdrawn, sleepy — most often missed), mixed.
Any acute change in cognition/behavior in an older adult is delirium until proven otherwise.
Common causes: infection (UTI, pneumonia), medications, dehydration/electrolytes, hypoxia, pain, constipation, sensory deprivation, sleep deprivation — often multiple at once.
Delirium vs. dementia: acute/fluctuating/reversible-potential vs. chronic/progressive/irreversible; they can coexist.
Classic science: Engel & Romano (1959) linked delirium to diffuse EEG slowing; Inouye's Hospital Elder Life Program (1990s) showed prevention with non-drug interventions.
Nurse's job: know the baseline, recognize acute change, escalate to the provider, and apply prevention measures (orientation, mobilization, sleep, sensory aids).
Delirium is a medical urgency, not a behavior problem — never dismissed as "just confusion" or blamed on the patient.

Check yourself

6 review questions from the chapter. Try each one, then open the answer.

List the defining features of delirium.
Show answer
Acute onset (hours to days), fluctuating course, inattention, altered level of consciousness, disorganized thinking, often with sleep-wake disturbance and perceptual changes — all caused by an underlying medical condition.
Why is hypoactive delirium dangerous, and who is most at risk of missing it?
Show answer
Because the withdrawn, sleepy patient draws no attention, so recognition — and treatment of the cause — is delayed, and delays worsen outcomes. It is most often missed by busy teams expecting agitation.
Name four common causes of delirium in older adults.
Show answer
Any four of: infection (UTI, pneumonia), medications (anticholinergics, sedatives, opioids), dehydration/electrolyte disturbances, hypoxia, pain, constipation/urinary retention, sensory or sleep deprivation.
How is delirium different from dementia, and why can the two coexist?
Show answer
Delirium is acute, fluctuating, attention-based, and potentially reversible; dementia is chronic, progressive, and irreversible. They coexist because dementia is a major risk factor for delirium — a person with dementia can develop delirium on top of baseline.
What did Engel and Romano contribute, and what did Inouye's HELP program show?
Show answer
Engel and Romano (1959) linked delirium to diffuse EEG slowing, establishing it as a physiological syndrome. Inouye's HELP program (1990s) showed non-drug prevention (orientation, mobilization, sleep, sensory aids) substantially reduces delirium in hospitalized older adults.
What is the nurse's first action when an older patient shows an acute change in cognition?
Show answer
Recognize it as an acute change from baseline, document onset and pattern, and escalate immediately — notify the provider and follow facility policy so the underlying medical cause is evaluated without delay.

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Study tools & related lessonsKey vocabulary · Related

Key vocabulary

Delirium: Acute, fluctuating disturbance of attention and cognition caused by a medical condition
Inattention: Inability to focus or sustain attention
Hyperactive delirium: Agitated, restless, sometimes hallucinating
Hypoactive delirium: Withdrawn, drowsy, hard to engage
Fluctuating course: Symptoms come and go, often worse at night
Confusion Assessment Method (CAM): A structured tool for identifying delirium
Hospital Elder Life Program (HELP): Bundle of non-drug delirium-prevention interventions (orientation, mobilization, sleep, sensory aids)
Baseline cognition: The person's usual level of thinking and awareness
Sundowning: Worsening confusion in the evening/night

Sources & references

openstax.org — Psychiatric Mental Health

This lesson was adapted from the open educational references above; their licenses and attributions are preserved. See Copyright & Licensing.

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