A skewed circle and misplaced numbers on a watch can show how dementia affects the brain. The clock drawing test is one of the tools used to diagnose the condition of patients.
“It's about 85% reliable,” says Professor Graham Stokes. It depends on how the patient remembers the watch - a skill known as executive function that allows us to plan, organize, and complete tasks, adds Dr. Tim Binland of the Alzheimer's Society.
Patients draw a circle and numbers from 1 to 12 showing the clock. Then they should draw the hour hands showing 11:10.
“This involves more processes than we think,” says Dr. Beenland. "You have to remember how to draw a circle, sequence 1-12 and how to draw time."
The above image itself was published in Figure 1, a website that allows doctors to exchange medical images and communicate with colleagues from around the world. The clock was drawn by a 70-year-old woman with mild dementia, unable to do without some help.
“This pattern can be assessed as a 'deep violation', since only 12 and 6 are in the right place,” says Professor Stokes. Although the patient positioned 11:10 correctly, it is clear that this was done with effort - because the order of the numbers is wrong.
However, the arm movements are correct, which suggests that the frontal lobe, which is responsible for solving the problem, is not damaged, as is the case with many Alzheimer's patients.
“The part of the brain that I think is damaged is the parietal lobe, which is responsible for spatial and visual perception and impairs the ability to see accurately,” says Professor Stokes.
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The patient also shows signs of left-sided inattention and spatial ignorance. “The right side of the brain controls actions on the left,” he says. "That explains why the left side of this picture is blank."
He believes the patient may be suffering from Alzheimer's disease and vascular dementia. The latter occurs when brain cells are deprived of oxygen and die, for example after a major stroke or a series of small strokes.
At the same time, Dr. Binland warns that the test should always be evaluated by a professional, since other factors, in addition to dementia, play a role.