Drawing a clock: a test that reveals the state of our mental health

The clock drawing test is a very simple diagnostic test to apply. Its purpose is to evaluate the cognitive deterioration of patients and to diagnose possible neurological and psychiatric disorders. Since it was first applied in 1953, it is usually one of the most common tests for early identification of Alzheimer’s disease or other dementias.

It is very possible that right now, if we say that this test is “solely” based on asking a person to draw a clock whose hands mark 11 and 10, more than one may doubt its validity and diagnostic effectiveness. However, there are a few practical aspects that we must consider about what this (apparently) simple task entails.

First of all, you need to understand the requested order: “Draw a clock that shows that time.” Later, the person must plan, take care of their motor execution, adjust their visual perception, visual-motor coordination and visual-constructive capacity. It’s not just anything, it’s more, The cognitive efficiency required by the clock test makes it one of the most useful tests, especially if we compare it with other more complex, more expensive and less reliable ones.

Clock drawing test to evaluate a deficit in cognitive abilities

This test was developed and applied for the first time in 1953. The aim was to assess constructive apraxia (common in dementia) and also identify the extent of lesions of the parietal cortex. Little by little, and seeing its effectiveness, it became an essential instrument for diagnosing the cognitive deterioration associated especially with the early phases of Alzheimer’s disease.

The administration of this test, as we have noted, is simple. However, it must be guided and analyzed by a trained psychologist, since various disorders, deficits or brain injuries can be identified from the clock drawing test. It should also be said: There are up to 15 different ways to evaluate this test.

How is the clock test applied?

Generally the professional can choose to administer the test in two ways:

Drawing of the clock by instructions. In this case, the patient is given a blank sheet of paper where he must draw a clock that says 11:10. It is important that the dial contains the correct distribution of each hour. Otherwise, the person can also be asked to copy the model of an already drawn clock. The copy must be exact: numbers, size of the dial, hands… When the patient finishes the test, she is asked if she has finished and if she thinks she has done well.

It is very possible that we are wondering now why the clock is chosen to show exactly 11:10. Something as simple as this implies that the 2 visuo-attentional hemifields must participate. It also requires that the person attend to the instruction, understand it, remember what clocks are like, how each time zone is distributed, and adequately plan where each hand is.

How is the clock drawing test evaluated?

As we have pointed out, there are many ways to evaluate this test. Normally the dial, the order of placement of the numbers, the orientation, if they are inside or outside the sphere, if they are only on one side or if there is even an excess of numbering. In the case of patients with schizophrenic disorders, for example, there usually appears an almost millimetric obsession with pointing out every minute on the dial, which makes the drawing a bizarre, variegated and almost unintelligible composition.

For example, A score is usually given to the drawing based on each of its components. Lower scores correspond, in turn, to a higher level of cognitive impairment. The evaluation of the drawing is done following this guide:

Sphere: The score ranges from 0 to 2, depending on its symmetry, its shape or whether it has not been drawn.Numbers: The score ranges from 0 to 4 and varies depending on whether all the numbers are there, if the sequence and location is correct, if they are all inside the sphere, among other characteristics.Hands: The score also ranges from 0 to 4 and is determined based on criteria such as whether the two hands have been drawn, whether they are located marking the assigned time or whether they are joined in the center of the dial.

Depending on the type of test performed (by instructions or by imitation) the cut-off points to evaluate the test may be different. In the case of the test by instructions, we speak of cognitive impairment when the score is less than 6; On the other hand, in the test through imitation of an already given drawing, the limit score is 8.

The case of a patient

María is 80 years old and goes to see a psychologist for the first time with her children.. “I forget things”, she says between laughs while her family nods their heads with a worried expression. The professional, after collecting some data and having a conversation with María to relax her and get to know her a little better, asks her to draw a clock that shows a very specific time, 11:10. The result is what we see below.

María’s cognitive deterioration is evident. This test will not be the only one performed on this patient; the diagnosis of Alzheimer’s will be confirmed (or not) with other neuropsychological strategies. However, the clock drawing test is a starting point and offers reliable and revealing information.

María is already elderly and the loss of cognitive faculties is common. Likewise, it should be said that In recent years this test has become much more refined. There is even a pen designed by the “Massachusetts Laboratory for Artificial Intelligence and Computer Science” (MIT) that records the person’s pulse, precision, interruptions, tremors and other types of irregularities.

Thanks to this technology, thousands of parameters can be extracted, however, the most interesting thing about all of this is that very early diagnoses of Alzheimer’s or Parkinson’s disease can be made. Early detection would offer us the opportunity to develop better strategies, to apply appropriate treatments with which to offer comprehensive care to the patient and a better quality of life to slow the course of the disease. Therefore, the clock drawing test will continue to be one of the best tools for detecting this type of disease.

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