What is the 4AT?
The 4 'A's Test or 4AT is a screening instrument for delirium and cognitive impairment.
The 4AT is free to download and use.
The 4AT is designed to be used by any health professional at first contact with the patient, and at other times when delirium is suspected. It incorporates the Months Backwards test and the Abbreviated Mental Test - 4 (AMT4), which are validated short tests for cognitive impairment. The primary aim of the 4AT is to assist in increasing detection rates of delirium in acute general hospital settings, though it can be used with patients with possible delirium in other settings. Its main features are:
The 4AT underwent several waves of piloting before reaching the form it is in now. The performance of the 4AT has been examined in two published studies (see References), and is also being tested in a multicentre study. In parallel with the formal studies, the 4AT is also being evaluated in practice in several clinical units globally. The 4AT was first published in September 2011 (version 1.0: see Archive), and an updated version (1.1) was published on this website on 1st May 2014.
Notes on version 1.1: The updated version of the 4AT is unchanged with respect to the testing items and scoring. The updates involve the interpretation of a score of zero on the 4AT, and the guidance notes. Regarding a score of zero, version 1.0 stated: 'delirium or cognitive impairment [is] unlikely'.Version 1.1 states that a score of zero suggests that 'delirium or severe cognitive impairment [is] unlikely'. This change was made because some people who show no errors on both Months Backwards (to 7 months) and the AMT4 may show some cognitive impairment when tested using more detailed and longer assessments. This issue also applies to other brief cognitive screening tests, eg. the 10-item Abbreviated Mental Test and the Mini-Mental State Examination. Note that the change to the interpretation of a score of zero in version 1.1 applies only to the detection cognitive impairment, not to delirium.
Authors: The 4AT was designed by Prof Alasdair MacLullich, Dr Tracy Ryan and Dr Helen Cash of the University of Edinburgh and NHS Lothian, Edinburgh, Scotland. We thank the following colleagues for generously contributing their time and expertise during the initial development and testing of the 4AT: Dr Atul Anand, Dr Daniel Davis, Dr Fergus Doubal, Dr Duncan Forsyth, Dr Kyle Gibson, Dr Aditya Hosakere, Prof Bree Johnston, Mr Colin MacDonald, Dr Katie Marwick, Dr Johanna Paddison, Prof Emma Reynish, Dr Jeyakumar Selwyn, and Dr Susan Shenkin.
The authors welcome any comments, suggestions or criticisms. Contact: Prof Alasdair MacLullich (firstname.lastname@example.org; @A_MacLullich).
Are you using the 4AT? Would you be willing to undergo a brief web survey to help in the development of the 4AT? If so, please email
Disclaimer: responsibility for the interpretation of scores and any actions rests with the clinical team using the 4AT.