Signature Test — Abnormal Signature Test

What this tool is and how to interpret its evidence

The Abnormal Signature Test is a very brief handwriting observation evaluated in older medical inpatients with and without delirium. It rests on the finding that delirium can disturb the organisation and execution of familiar writing. Asking for a signature takes under 30 seconds and may be possible when longer verbal testing is difficult.

Adamis and colleagues studied dysgraphia in 2006. A later systematic review tabulated sensitivity of 54% and specificity of 88% for an abnormal signature. That combination makes the sign too insensitive to exclude delirium: almost half of affected patients could be missed. Handwriting can also be altered by stroke, tremor, weakness, arthritis, poor vision, literacy, unfamiliar script or chronic neurological disease.

The test should be included only as historical or experimental context. Its omission while the Delirium Writing Test remains in the core is otherwise inconsistent. The two records should cross-link, and neither should be presented as equivalent to a multidomain delirium assessment. A page may describe the single-task concept, speed, study performance and practical confounders. It does not need to reproduce example signatures or diagnostic rules. An abnormal result can add to concern, but a normal signature does not safely rule out delirium and should never delay appropriate assessment.