Neurology

4AT Delirium Screening Score

Rapid bedside delirium screening tool

Primary source: Bellelli G et al. Age Ageing 2014; 43(4): 496-502

Aleksandr A. Aulov, MD, internal medicine Last clinical review: April 28, 2026

Online calculation

[A] Alertness

[A] AMT4 (state age, date of birth, place, year)

[T] Attention (recite months of the year backwards)

[T] Acute onset or fluctuating course

About this score

The 4AT (4 'A's Test) is a brief screening test for delirium and cognitive impairment in older adults. Developed in Edinburgh (MacLullich AM, 2014) specifically for use in the emergency department and general medical wards. Requires no special training and takes less than 2 minutes.

It includes 4 components: Alertness, AMT4 (Abbreviated Mental Test - 4 questions: age, date of birth, current year, place), Attention (months of the year backwards), and Acute change (acute change or fluctuation in cognitive status over the preceding 2 weeks).

Interpretation: 0 is normal; 1-3 suggests possible cognitive impairment without delirium; ≥ 4 indicates probable delirium. Sensitivity for delirium is 89.7%, specificity 84.1%. NICE 2023 guidance includes the 4AT as a standard screening tool on admission for older patients to hospital.

When to use

Delirium screening on admission in patients ≥ 65 years.
Older patient with behavioral or cognitive change (agitation, anxiety, apathy).
Postoperative period in older adults - daily screening.
Differentiating delirium from dementia (delirium: acute, fluctuating course; dementia: chronic).

Clinical example

Case

An 82-year-old man is admitted with a fractured neck of femur. His daughter reports, 'he was fine yesterday, but today he doesn't recognize us.' On examination: agitated, unable to state his location or the current year, or recite the months backwards. Alertness is preserved.

Calculation

Alertness (normal, 0) + AMT4 (≥ 2 errors - 2) + Attention (unable to recite - 2) + Acute change (present - 4) = 8 points.

Interpretation and management

A score ≥ 4 indicates delirium is highly likely. Management: search for reversible causes (hypoxia, infection, dehydration, electrolyte disturbance, pain, new medications), review medications (discontinue benzodiazepines and anticholinergics where possible), and non-pharmacological measures (patient's own glasses/hearing aids, mobilization, sleep optimization, presence of family). Antipsychotics only if the patient or others are at risk, at the lowest effective dose and for the shortest duration.

Limitations and cautions

Absence of an acute change (Acute change = 0) scores 0 points - but hypoactive delirium without a witness account may be missed.
In patients with severe dementia, baseline errors on AMT4 are expected - assess the change from baseline rather than the absolute score.
Post-stroke aphasia distorts the Attention and AMT4 components.
Does not diagnose the type of dementia (Alzheimer, vascular, Lewy body) - MMSE, MoCA, and neuroimaging are needed for that.

Frequently asked questions

How does 4AT compare with the CAM (Confusion Assessment Method)?

The 4AT is shorter (2 minutes vs 5-15 minutes for the CAM), requires no training, and can be used in patients with severe dementia. Sensitivity is comparable.

What should be done with a 4AT score of 1-3?

This suggests possible cognitive impairment without delirium. Obtain a history from family regarding chronic cognitive problems. If uncertain, retest after a few hours.

Can it be used in a patient with aphasia?

With caution. The Attention and AMT4 components are not valid. Alternative scales (e.g., the Observational Delirium Scale) should be used.

How often should it be repeated?

Daily in high-risk patients (older adults in critical care, postoperative patients). Repeat immediately if there is any sign of deterioration, regardless of timing.

All clinical calculators in one place

Validated scores and formulas with full interpretation, clinical examples and source references. Open access, no registration required.

65+ calculators · scores and formulas · interpretation with management notes

Browse all calculators

АА

Aleksandr A. Aulov Physician, internal medicine, Sechenov School — independent medical education platform. Calculators are compiled from the original publications and current clinical guidelines. Interpretation thresholds follow the source study unless stated otherwise.

This calculator is intended for healthcare professionals. Do not use it for self-diagnosis or self-treatment. Management decisions are made by the treating clinician based on the full clinical picture of the individual patient.