This is a common test used to screen for dementia and to track its progression.
In this test, the patient is first asked to draw a circle which will represent the face of a clock (in some cases, a printed circle is presented to him/her). Then the patient is asked to label the 12 numbers in their appropriate places and then draw the two hands of the clock to indicate the time of ten minutes past eleven.
Seemingly simple, the test examines a lot of the functions of the brain. The patient has to be able to:
- understand and remember the instruction
- plan and execute the instruction
- be able to visually remember the image of the clock
- be able to distribute the numbers around the clock evenly
- be able to put the numbers and hands in the correct place
- have enough concentration to finish the task.
It is easy to administer, takes only a few minutes and requires minimal equipment. Unlike the MMSE (Mini-Mental State Examination), it depends less on language skill and education.
However, there are many ways of administering this test and there are at least twenty different scoring systems! Some are simple but some are very complicated. Nevertheless, all these different methods have been proven to be able to detect dementia.
The following is an example of one of the simpler ways of administering and scoring the test:
The patient will get one point for each correct action:
- Able to draw a circle
- Able to put in all twelve numbers in the correct order
- Able to place the numbers in the correct place on the clock face
- Able to draw the two hands on the clock
- Able to point the two hands to the correct time
Four to five points indicate normal cognition. Further investigation into dementia will be required for those scoring less than 4 points.
Healthcare professionals also use this to track the progression of the dementia and have also used the different types of mistakes to distinguish between the different types of dementia.
Regrettably, with the common usage of the digital clock, this test may become less effective within the next couple of generations.
Written by Dr. Kenneth Chan