Dementia testing by means of a clock test
Dementia (such as Alzheimer’s disease or vascular dementia) can be diagnosed using various test procedures. One of these is the clock drawing test. It is easy to perform and takes only a few minutes. It is recommended for the 65- to 85-year-old age group.
However, the clock test is not suitable as the sole diagnostic tool for dementia. It is therefore always combined with another test for early dementia detection (MMST or DemTect).
Clock test: How it works
There are different variants of the clock test. In Germany, the template by Shulman (1993) is usually used: Here, the test person is asked to write the numbers “1” to “12” in a given circle, as they are arranged on the face of a clock. In addition, the minute and hour hands are to be drawn in so that they indicate a specific time (usually 11:10 a.m.).
Sometimes the clock test variant according to Sunderland et al. (1989) is also used. Here, the test person must also draw the clock face itself (i.e., the circle).
Watch test: Evaluation
When evaluating the watch test, it is not only important whether all the digits and the two hands are in the correct position. The examiner also pays attention, for example, to whether the distances between the numbers are approximately equal and whether the numbers are clearly legible.
The more advanced the dementia, the more difficult the clock test is for the person affected: The drawn clock becomes increasingly unrecognizable, the numbers and hands are drawn in incorrectly or are even missing. In severe dementia, many patients no longer even attempt to draw a clock. Some write words or their name on the paper instead.
The score on the Shulman (1993) clock test is rated on a scale from “1” (perfect) to “6” (no representation of a clock).
The clock test evaluation in the variant according to Sunderland et al. (1989) is based on a scale from “10” (correct representation) to “1” (no longer recognizable as a clock).
Minute hand phenomenon
Sometimes the dial with its numbers and the hour hand are displayed correctly, but the minute hand is placed incorrectly. This so-called minute hand phenomenon in the clock test can indicate the onset of dementia.
