Hypoactive delirium in the elderly: 4AT and CAM

An 84-year-old man had surgery for a femoral neck fracture two days ago. On the night shift, the team noted "patient calm, cooperative, slept well". In the morning, the breakfast tray comes back almost untouched, and the glass of water is still full. He answers "yes" to almost everything, looks at the window and dozes off in the middle of the conversation. At handover, the nurse applies the 4AT: the patient is drowsy, gets simple orientation questions wrong, loses track when saying the months of the year backwards, and his daughter says on the phone that, before surgery, he read the newspaper and did his own accounts. The scene is fictional and was written for teaching.

This text uses the case as a scenario for clinical reasoning in nursing. The quiet patient looks like the patient who causes the least trouble. Together, inattention, drowsiness, acute onset and a change from the usual tell another story: hypoactive delirium, the form that goes unnoticed most often. The text does not replace your institution's protocol or the medical prescription. If you play the case of the day on NEXO, you will recognize the challenge: being suspicious of the patient who asks for nothing.

Key points

• Delirium is an acute disturbance of attention and cognition, common in hospitalized older adults and often unrecognized.
• The hypoactive form shows up as drowsiness, slowness and apathy, and is mistaken for depression, tiredness or dementia.
• After hip fracture, delirium is frequent, especially in those who already have dementia.
• The 4AT is a short screening tool that nursing can apply at the bedside; 4 points or more suggest delirium.
• Delirium is a sign: the team looks for the cause, such as pain, infection, urinary retention, drugs and metabolic disturbances.
• Non-pharmacological measures are the foundation; antipsychotics are not routine treatment.

Why this is a reasoning scenario

Delirium is frequent in hospital and costly. Inouye and colleagues describe a problem that affects up to half of hospitalized older adults, is often unrecognized and is associated with worse outcomes; they also estimate that it is preventable in 30 to 40 percent of cases (Inouye and colleagues, 2014). In a Dutch cohort of older adults with hip fracture, 35 percent had delirium, and the condition was associated with longer hospital stay, more complications, institutionalization and six-month mortality (Mosk and colleagues, 2017).

The scenario is good for training because the main clue is an absence. The patient does not shout, does not pull out the line, does not try to get out of bed. He simply stops taking part. The post on signs, symptoms and history shows how to read what the patient brings, and the post on clinical deterioration on the ward reminds us that new confusion is a warning sign even when the other numbers look good.

The cost of delay

In a study of 82,770 emergency admissions at two British centers, a 4AT of 4 points or more on admission was associated with 30-day mortality 5.5 times higher at one center and 3.4 times higher at the other, compared with a 4AT of zero (Anand and colleagues, 2022). Hospital stay was more than double, and time at home in the following year fell (Anand and colleagues, 2022). Jackson and colleagues note that the longer hypoactive delirium goes unrecognized, the worse the long-term outcome (Jackson and colleagues, 2025).

What the scene teaches

The scene trains four habits. The first is to ask how the patient was before, not only how he is now. The second is to test attention with an instrument, instead of trusting the impression of "calm". The third is to treat delirium as a sign that calls for a search for the cause. The fourth is to know which measures help and which get in the way.

What delirium is and why the hypoactive form goes unnoticed

Delirium is an acute disturbance of attention and cognition; diagnosis requires formal cognitive assessment and a history of acute onset of symptoms (Inouye and colleagues, 2014). Inouye and colleagues describe it as "acute brain failure", a multifactorial condition analogous to acute heart failure (Inouye and colleagues, 2014).

Three forms

There are three main forms: hyperactive, hypoactive and mixed (Jackson et al., 2025). In the hyperactive form, the patient is agitated, restless, may have hallucinations and incoherent speech. In the hypoactive form, lethargy, drowsiness and reduced response appear, with the patient disconnected from the environment (Jackson et al., 2025). In the mixed form, the patient alternates between the two (Jackson et al., 2025). Inouye et al. note that the predominantly hypoactive form is more common in older adults and is associated with a worse prognosis, and that the patient may fluctuate between forms throughout the day (Inouye et al., 2014).

Why it goes unnoticed

Hypoactive delirium is easily confused with depression, fatigue or dementia (Jackson et al., 2025). Peritogiannis et al. recall that delirium is widely underdiagnosed, largely due to the difficulty in recognizing the hypoactive form, and propose regularly assessing signs of this form in daily practice (Peritogiannis et al., 2015). In a retrospective study of hospitalized older adults in the Netherlands, the recorded prevalence of delirium was only 5 percent, with 23 percent of episodes classified as hypoactive; the authors conclude that there was likely significant underreporting (van Velthuijsen et al., 2018).

Family as a sensor

Family members and close friends are often the first to notice subtle and acute changes (Jackson et al., 2025). The daughter who says "he is not like this" is providing the information that defines the acute onset. Jackson et al. argue that the team should work with the family in detection and care (Jackson et al., 2025).

Finding	Hypoactive delirium	Dementia	Depression
Onset	Acute, hours to days	Slow, months to years	Weeks
Attention	Very altered, fluctuates	Preserved at first	Generally preserved
Level of consciousness	Drowsy or reduced	Normal at first	Normal
Course throughout the day	Fluctuates	Stable	Stable
What the family says	Changed suddenly	Has been getting worse for a while	Seems sad, without interest

Table sources: (Inouye et al., 2014), (Jackson et al., 2025) and (Bellelli et al., 2014). The conditions can coexist: dementia is the greatest risk factor for delirium.

Who is most at risk

Delirium arises from the encounter between vulnerability and insult. Inouye et al. describe a well-validated model: in a very vulnerable patient, with dementia and several diseases, a small insult, such as a dose of sleeping medication, may be enough; in a young and healthy patient, only a sum of insults, such as general anesthesia and major surgery, triggers the condition (Inouye et al., 2014). The most consistent risk factors on admission were dementia or cognitive impairment, functional dependence and visual impairment, among others (Inouye et al., 2014).

Hip fracture

In the cohort by Mosk et al., with a median age of 84 years, the risk factors for delirium were high ASA score, previous delirium, functional dependence, institutionalization before surgery, low hemoglobin and large transfusion volume (Mosk et al., 2017). Patients with dementia had delirium 57.7 percent of the time (Mosk et al., 2017). In a Chinese study of 306 older adults operated for hip fracture, 19.29 percent had postoperative delirium, and age over 75 years, diabetes and ASA greater than 2 were independent factors (Wang et al., 2018).

What nursing notes on admission

• Usual cognitive and functional status, asked to the patient and family.
• Previous diagnosis of dementia or previous episode of delirium.
• Glasses and hearing aid: whether they exist and whether they came with the patient.
• List of continuous-use medications, including sleeping pills.
• Alcohol and sedative use at home.
• Sleep, eating and elimination habits.

List source: (Inouye et al., 2014). This information becomes the baseline against which screening will be compared.

How to screen: the 4AT and the CAM

Clinical impression is not enough to catch hypoactive delirium. Short instruments standardize the question and allow comparing shifts.

The 4AT

The 4AT has four items. The first assesses level of alertness. The second is a short orientation test, the four-question Abbreviated Mental Test (AMT4). The third tests attention by asking for the months of the year backwards. The fourth assesses acute change or fluctuation in mental status (Bellelli et al., 2014). The score ranges from 0 to 12: zero suggests delirium and moderate to severe cognitive impairment are unlikely; 1 to 3 suggests possible cognitive impairment; 4 or more suggests possible delirium (Bellelli et al., 2014). The test requires no special training and usually takes less than 2 minutes (Bellelli et al., 2014).

How well it works

In the validation study with 234 hospitalized older adults, sensitivity was 89.7 percent and specificity 84.1 percent for delirium (Bellelli et al., 2014). In a meta-analysis of 17 studies, the pooled sensitivity and specificity were both 0.88 (Tieges et al., 2021). In a multicenter study with 785 older adults on a medical ward, the 4AT had sensitivity of 76 percent and specificity of 94 percent, while the CAM, applied in routine practice, had sensitivity of 40 percent and specificity of 100 percent (Shenkin et al., 2019).

The CAM

The Confusion Assessment Method organizes the diagnosis around four features: acute onset with fluctuating course, inattention, disorganized thinking and altered level of consciousness. The result is positive when the first two are present and at least one of the other two (Shenkin et al., 2019). The CAM requires specific training to score each feature (Shenkin et al., 2019); the study by Shenkin et al. suggests that, without that training, it misses cases that the 4AT detects (Shenkin et al., 2019). In intensive care, adapted versions such as the CAM-ICU are used in patients who cannot speak.

Applying it to the case

The patient in the scene is drowsy (scores on alertness), gets two orientation items wrong (scores on the AMT4), loses track of the months (scores on attention) and, according to his daughter, changed acutely (scores on the fourth item). The total is well above 4. It is not "age" or "surgical fatigue".

Looking for the cause

Delirium is not a final diagnosis; it is a sign that something is harming the brain. Inouye et al. note that, because the cause is often multifactorial, correcting a single factor rarely resolves it, and approaches with several components are more effective (Inouye et al., 2014).

Mechanisms

Among the neurotransmitters involved, the most cited are a relative deficiency of acetylcholine and an excess of dopamine, which matches the adverse effects of anticholinergic and dopaminergic drugs (Inouye et al., 2014). The systemic inflammatory response, as in sepsis, can trigger neuroinflammation, with endothelial activation, impaired blood flow and neuronal death (Inouye et al., 2014). This explains why a urinary tract infection or pneumonia can first appear as confusion.

What to look for, in practical order

• Untreated pain, which a quiet patient does not report.
• Urinary retention and constipation, with abdominal palpation and monitoring of urine output.
• Hypoxia: oxygen saturation, respiratory rate and breathing pattern.
• Capillary blood glucose, for hypoglycemia or hyperglycemia.
• Signs of infection: fever, surgical wound, urine, lungs, lines.
• New or added drugs: opioids, sedatives, anticholinergics, sleep aids.
• Dehydration and sodium disturbances, which call for lab tests requested by the team.

Source of the list: (Inouye et al., 2014). Lab and imaging workup is decided by the medical team.

In the case in the scene

The patient drinks little, which points to dehydration and a possible sodium disturbance. He received an opioid postoperatively and may have poorly controlled pain. He is bedbound, with a risk of urinary retention and constipation. He had surgical bleeding and may be anemic. Each item is a concrete question for the shift handover.

What to do at the bedside

The actions below follow the cited sources and the logic of treating the cause while protecting the brain. The exact sequence depends on the local protocol.

Communicate clearly

A structured message helps: "84-year-old patient, second postoperative day after hip fracture. 4AT of 4 or more now, with drowsiness, inattention and an acute change confirmed by her daughter. Drank little in the last 24 hours, received an opioid during the night. I request evaluation for delirium and investigation of the cause: pain, urine output, blood glucose, sodium, infection and medication review." The sentence gives the finding, the instrument, the change from baseline and the hypotheses.

Non-pharmacological measures

Inouye and colleagues recommend non-pharmacological approaches as first line: withdraw or reduce anticholinergic and psychoactive drugs, involve family or a companion for reorientation and comfort, support sleep and relaxation without medication, create a calm environment and manage pain (Inouye and colleagues, 2014). The Hospital Elder Life Program, the most widespread strategy, includes reorientation, therapeutic activities, reduction of psychoactive drugs, early mobilization, sleep promotion, hydration and nutrition, and adaptations for vision and hearing (Inouye and colleagues, 2014). A systematic review of trials with nursing interventions found strategies with family, multimedia resources, music, sleep management, orientation, reinforced communication and nutritional management (Lee and colleagues, 2021). A review in intensive care and palliative care found evidence that non-pharmacological methods are effective in preventing delirium (Chan and Corso, 2024).

In nursing practice

Glasses and hearing aid in place and clean. Clock and calendar visible, and the team saying where the patient is and what day it is. Natural light during the day and darkness with silence at night, grouping care so as not to wake the patient several times. Help to eat and drink, with water within reach. Sitting and walking as soon as the team allows. Family present whenever possible. Physical restraint and bed alarms avoided, because they increase the risk and persistence of delirium and the risk of injury (Inouye and colleagues, 2014).

Antipsychotic is not routine

Inouye and colleagues state that there is no convincing evidence that pharmacological prevention or treatment is effective, and that antipsychotics can reduce agitation without improving the delirium outcome (Inouye and colleagues, 2014). They reserve pharmacological treatment for severe agitation that interrupts essential therapies or severe psychotic symptoms (Inouye and colleagues, 2014). A systematic review of 39 studies showed that antipsychotics remain widely used in delirium, often at doses, frequency and duration outside the recommendations, even though international guidelines discourage this use (Tomlinson and colleagues, 2024). The authors recall that, especially in older adults, the antipsychotic carries a risk of worse progression and longer delirium (Tomlinson and colleagues, 2024). In hypoactive delirium, where there is no agitation to control, the argument for sedating is even weaker. The decision about any drug is medical and follows the prescription.

What not to do

Do not label the patient as "demented" without asking how they were before. Do not give sleeping medication because they "swapped day for night" without discussing it with the team. Do not leave the patient without glasses and without a hearing aid because "they don't complain". Do not interpret quietness as improvement.

Step-by-step reasoning in the case

It is worth retracing the case path in order, as if the clues arrived one by one.

First clue: "calm and cooperative"

The night record is reassuring, but it is a description of behavior, not a cognitive assessment. In an 84-year-old who underwent hip surgery, the right question is whether this quietness is their usual way or a change.

Second clue: the full tray and glass

Eating and drinking little after surgery has several explanations: nausea, pain, lack of appetite. But it can also be inattention. The patient did not forget to be hungry; they cannot sustain attention on the task of eating. And low intake is itself a factor that can worsen the picture.

Third clue: the 4AT

Drowsiness, orientation errors and failure in the months backward take the picture out of the realm of impression. With the acute change confirmed, the 4AT suggests delirium (Bellelli and colleagues, 2014).

Fourth clue: the daughter

The information that he used to read the newspaper and do his own accounts rules out the idea that "he was already like this". The acute onset is what separates delirium from dementia, and it is usually the family who provides it (Jackson et al., 2025).

Fifth clue: looking for the cause

With delirium recognized, the question changes to "why now?". Pain, opioids, dehydration, urinary retention, anemia, infection and sodium imbalance go on the list. The plan combines treating whatever is found and applying non-pharmacological measures right away.

Hypothesis	For	Against	What decides
Hypoactive delirium	Acute onset, inattention, drowsiness	Nothing against so far	4AT or CAM, family history
Prior dementia	Age, disorientation	Was independent before surgery	Baseline status from the family
Depression	Apathy, eats little	Acute drowsiness and inattention	Course and assessment of attention
Opioid effect	Recent opioid, drowsiness	Inattention persists while awake	Review of prescription and sedation
Organic cause (pain, retention, sodium, infection)	Postoperative, low intake	Tests not yet done	Physical exam, urine output, tests

Table sources: (Inouye et al., 2014), (Bellelli et al., 2014) and (Jackson et al., 2025). The table organizes the reasoning; the diagnosis belongs to the team.

How NEXO helps train this reasoning

In NEXO, you try the diagnosis by searching for the ICD-10 code and get feedback on proximity in five levels, which shows whether your guess landed on the exact code, the same category, the same group, the same chapter or a different chapter. This format fits the theme of this text: delirium, dementia, depression, hyponatremia and urinary infection sit in different chapters of the classification, but can all start with the same quiet older adult. The post about ICD-10 shows how to find the right code.

To use the case of the day as training, try three habits. Before your first guess, ask how the patient was before. With each clue, ask whether it speaks of attention or only of behavior. After the result, note down the clue you read as "normal for age".

Three exercises with cases

Define the baseline. In each case with an older adult, say which information would show the cognitive state before admission.

Test attention. Say which 4AT item you would apply first and why.

Look for the cause. List three treatable causes of acute confusion that would fit the case.

The post about differential diagnosis with clues shows how to organize hypotheses, the post about simulated consultations shows how to train patient assessment, the post about case-based learning shows how cases help fix these habits, and the post about diagnostic uncertainty discusses how to decide when the data do not yet add up.

The limits on using the game are described on the NEXO economy page. If you research the teaching of clinical reasoning, the page for researchers explains how to get in touch. Professionals who write or review cases find information under curation and creators, and institutions can learn about the proposal on the partnerships page.

Frequently asked questions

What is hypoactive delirium?

It is the form of delirium with lethargy, drowsiness and reduced responsiveness, without agitation (Jackson et al., 2025).

How do you tell it apart from dementia?

By the acute onset and the fluctuating inattention; the family usually says the change was recent (Inouye et al., 2014), (Jackson et al., 2025).

Which 4AT score is worrying?

Four points or more suggest possible delirium (Bellelli et al., 2014).

Do antipsychotics treat delirium?

There is no convincing evidence that they improve the outcome, and guidelines discourage routine use (Inouye et al., 2014), (Tomlinson et al., 2024).

Can delirium be prevented?

Partly. Strategies with several non-pharmacological components are the most effective form of prevention (Inouye et al., 2014), (Chan and Corso, 2024).

Final checklist

• I recorded the usual cognitive and functional state with the patient and the family.
• I applied the 4AT or the CAM, without relying on the impression of "calm".
• With a 4AT of 4 or more, I communicated and asked for an investigation of the cause.
• I looked for pain, urinary retention, hypoxia, altered blood glucose, infection and drugs.
• I provided glasses and a hearing aid, reoriented the patient and involved the family.
• I protected nighttime sleep, encouraged hydration, food intake and mobilization.
• I avoided restraint and did not treat quietness as improvement.

Want to practice your reasoning with progressive clues? Play today's case.

References

1. Anand A, Cheng M, Ibitoye T, et al. Positive scores on the 4AT delirium assessment tool at hospital admission are linked to mortality, length of stay and home time: two-centre study of 82,770 emergency admissions. Age Ageing. 2022. PMID 35292792.
2. Bellelli G, Morandi A, Davis DH, et al. Validation of the 4AT, a new instrument for rapid delirium screening: a study in 234 hospitalised older people. Age Ageing. 2014. PMID 24590568.
3. Chan L, Corso G. Pharmacological and non-pharmacological prevention and management of delirium in critically ill and palliative patients in the inpatient setting: a review. Front Med (Lausanne). 2024. PMID 39086947.
4. Inouye SK, Westendorp RG, Saczynski JS. Delirium in elderly people. Lancet. 2014. PMID 23992774.
5. Jackson D, Le Lagadec D, Cleary M. Hypoactive Delirium: The Critical Need for Collaboration Between Families and Nurses in Prevention, Recognition and Care. J Adv Nurs. 2025. PMID 39878087.
6. Lee Y, Lee J, Kim J, et al. Non-Pharmacological Nursing Interventions for Prevention and Treatment of Delirium in Hospitalized Adult Patients: Systematic Review of Randomized Controlled Trials. Int J Environ Res Public Health. 2021. PMID 34444602.
7. Mosk CA, Mus M, Vroemen JP, et al. Dementia and delirium, the outcomes in elderly hip fracture patients. Clin Interv Aging. 2017. PMID 28331300.
8. Peritogiannis V, Bolosi M, Lixouriotis C, et al. Recent Insights on Prevalence and Corelations of Hypoactive Delirium. Behav Neurol. 2015. PMID 26347584.
9. Shenkin SD, Fox C, Godfrey M, et al. Delirium detection in older acute medical inpatients: a multicentre prospective comparative diagnostic test accuracy study of the 4AT and the confusion assessment method. BMC Med. 2019. PMID 31337404.
10. Tieges Z, Maclullich AMJ, Anand A, et al. Diagnostic accuracy of the 4AT for delirium detection in older adults: systematic review and meta-analysis. Age Ageing. 2021. PMID 33951145.
11. Tomlinson EJ, Schnitker LM, Casey PA. Exploring Antipsychotic Use for Delirium Management in Adults in Hospital, Sub-Acute Rehabilitation and Aged Care Settings: A Systematic Literature Review. Drugs Aging. 2024. PMID 38856874.
12. van Velthuijsen EL, Zwakhalen SMG, Mulder WJ, et al. Detection and management of hyperactive and hypoactive delirium in older patients during hospitalization: a retrospective cohort study evaluating daily practice. Int J Geriatr Psychiatry. 2018. PMID 28194812.
13. Wang CG, Qin YF, Wan X, et al. Incidence and risk factors of postoperative delirium in the elderly patients with hip fracture. J Orthop Surg Res. 2018. PMID 30049276.