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4AT Rapid Delirium Screen

The 4AT (0–12) screens for delirium using Alertness, AMT4, Attention (months backwards) and Acute change/fluctuation. ≥4 suggests possible delirium ± cognitive impairment; 1–3 possible cognitive impairment; 0 makes delirium or severe cognitive impairment unlikely.

1. Alertness: Normal (fully alert, not agitated) or mild sleepiness <10 s after waking (0); Clearly abnormal (drowsy, agitated, hyperactive) (4)
2. AMT4 (age, date of birth, place, current year): No mistakes (0); 1 mistake (1); 2 or more mistakes / untestable (2)
3. Attention: months of the year backwards: Achieves 7 months or more correctly (0); Starts but scores <7 months, or refuses to start (1); Untestable (cannot start: unwell, drowsy, inattentive) (2)
4. Acute change or fluctuating course: No (0); Yes (in alertness, cognition or other mental function, within last 2 weeks and still evident in last 24 h) (4)

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Interpretation

Result	Meaning
≥ 4	Possible delirium ± cognitive impairment
1–3	Possible cognitive impairment
0	Delirium or severe cognitive impairment unlikely

Formula

Alertness: normal 0, abnormal 4 · AMT4: 0 mistakes 0, 1 mistake 1, ≥2/untestable 2 · Months backwards: ≥7 correct 0, <7 or refuses 1, untestable 2 · Acute change/fluctuation: no 0, yes 4. Total 0–12.

Clinical pearls

A score of 0 does not exclude delirium if item 4 (acute change) information is incomplete.
Validated in hospitalised older adults (≥70 y in Bellelli 2014: sensitivity 89.7%, specificity 84.1%); a positive screen needs clinical assessment for delirium.
The 4AT is free to use (www.the4at.com); no training is required.

Examples

4at: alert, 1 mistake on amt4, could not do months backwards, acute change yes delirium screen for an 85 year old who is drowsy, got 2 AMT4 wrong, fluctuating since admission

FAQ

What 4AT score indicates delirium?

4 or more suggests possible delirium (with or without cognitive impairment) and should prompt clinical assessment.

Can the 4AT be used in drowsy patients?

Yes. Untestable items score points, so it can be completed in patients who cannot engage with testing.

Evidence

Bellelli G et al. Validation of the 4AT, a new instrument for rapid delirium screening: a study in 234 hospitalised older people. Age Ageing 2014;43:496–502.

Neurology · Reviewed 2026-10-14 · Methodology