You may have heard of the clock test before. It is commonly included in the battery of tests when making a dementia diagnosis. More than one test is used because doctors are first trying to rule out other causes for the cognitive impairments (such as tumors, stroke or other changes to the brain), to determine if the dementia symptoms could be reversible (such as with an infection or vitamin deficiencies), and to differentiate the type of dementia (if it is vascular, frontotemporal, etc.). Actually, the dementia test work-up is really a bunch of tests to rule out causes for the cognitive changes, and only when no other cause can be found, a diagnosis of dementia or probable dementia is given (or at least that is the ideal way the tests are used and a diagnosis of dementia is arrived at).
To do the clock test, the instructions are for the person to draw a clock and put the hands at a specific time that the doctor says (usually it is 11:10). The clock test is used to assess the cognitive processes of:
- Executive functioning,
- Organization: Gathering information and structuring it for evaluation
- Regulation: Taking stock of your surroundings and changing behavior in response to it
- Global cognitive status,
- The mechanisms of how we learn, remember, problem-solve, and pay attention rather than actual knowledge.
- Visuospatial abilities,
- The ability to understand visual representations and their spatial relationships.
- The act or faculty of attending, especially by directing the mind to an object; concentrating.
- and Semantic knowledge
- General facts, meaning, ideas, and concepts that are not drawn from personal experience.
Below are some examples of clock tests that people with dementia have completed.
How is the clock test scored and what do the scores mean?
There are many different ways to score the clock test, over a dozen at least. One study found that the easiest method for scoring was equally as accurate as the more difficult methods – good news! The easiest method is also the one recommended by the Alzheimer’s Association. 1 point is given for drawing the clock and getting the time correct (indicating the absence of dementia) and 0 points are given if these two criteria are not met (indicating further evaluation is needed).
Below, a more detailed description of the scoring is given.
There is also a 10-point scoring for the Clock Test:
Researchers at Georgia Tech are currently working on testing a home-based version of the Clock Test, called ClockMe. The person uses a stylus with their tablet or touchscreen computer to draw a clock at home. They are given directions and a set amount of time to complete the clock at 11:10. Then, they email the clock to a professional, who uses a special software called ClockAnalyzer to score the test. The individual person can also use another program, called ClockReader, to look at their test at home.
The ClockAnalyzer Application examines 13 characteristics of the drawn clock. These include, among other things, where the numbers are placed, how they are written, if there are extra or missing numbers, and if the time is set to 11:10, how long it took the person to finish their clock, the time between each stroke, and can even replay the entire drawing experience, which lets clinicians look further for abnormal behaviors. Really sounds like a useful application for diagnostics, if you ask me! I couldn’t find a more detailed description of the ClockReader program, but would imagine it would include some similar features and focus more on looking at the changes in the Clock Drawing Test over time rather than specific diagnostic indicators.
What does research say about the clock test?
Compared to the Mini-Mental State Examination (MMSE, another commonly used cognitive assessment tool), the clock drawing test is thought to have less educational bias and is better able to detect cognitive decline due to Alzheimer’s disease and other dementias. The MMSE is known to have some issues with the educational level of the individuals taking the test (those with high education levels can pass the test even though they have measurable impairment, and those with low education levels can do poorly on the test even though they have no impairment), as well as not being as sensitive to milder cognitive changes and is primarily sensitive to detecting Alzheimer’s than other dementias. The clock drawing test has also been advocated over the MMSE as an office screening test for dementia in community clinics and in acute hospital settings. It requires less time to administer and to score. Furthermore, the clock drawing test is suitable for non-English speaking populations, whereas the MMSE does have some language bias.
A 2010 study from researchers at the Alzheimer’s Disease Center at Boston University School of Medicine looked at interrater reliability (the degree of agreement among raters/clinicians) and diagnostic accuracy (how accurate the tool is in correctly diagnosing or ruling out a diagnosis) of the Clock Drawing Test. They found it had excellent interrater reliability, sensitivity (how good a test is at positively detecting a condition), and specificity (how likely the individuals without the disease will correctly be ruled out) for predicting a consensus diagnosis and excellent interrater reliability and sensitivity for differentiating participants with mild Alzheimer’s Disease from the control (normal cognition) participants. The researchers found that while the clock drawing test may be a good screening instrument for Alzheimer’s disease – although it is not recommended to use as a stand-alone screening, it may not be a sensitive instrument for screening mild cognitive impairment.
A literature review study, from 2015, looked at if the Clock Drawing Test could differentiate between types of dementia. They looked at data from 20 different studies and found that there were no significant differences in Clock scores between individuals with Alzheimer’s Disease, Vascular Dementia, Dementia with Lewy Bodies, and Parkinson’s Disease Dementia. They did find that individuals with Frontotemporal Dementia consistently scored higher than individuals with Alzheimer’s Disease. The authors conclude that the types of errors made on the Clock Drawing Test suggests that there is a difference between Alzheimer’s and other types of dementia and could be useful to distinguish between Alzheimer’s and Frontotemporal dementia.
In conclusion, the Clock Drawing Test is widely used, easy to administer and score, and has a high sensitivity to correctly detecting Alzheimer’s Disease. This test doesn’t take long, which makes it a good screening tool for a doctor to use to determine if further cognitive testing is needed, and even better to use as a screening tool in hospitals if there are suspicions of cognitive impairment. I really look forward to reading about the ClockMe and complimentary applications being tested at Georgia Tech and think this could be a promising step forward in dementia testing and diagnosis.
Have you or someone you know taken the Clock Drawing Test? I would be interested to hear your experiences and opinions in the comments below!
Kørner EA et al. Simple scoring of the Clock-Drawing test for dementia screening. Danish Medical Journal 2012 Jan; 59(1): A4365. http://www.danmedj.dk/portal/pls/portal/!portal.wwpob_page.show?_docname=8548905.pdf. Accessed 4 May, 2015.
Endear “Alzheimer’s disease screening test at home,” http://blogforalzheimers.com/2012/10/08/alzheimers-disease-screening-test-at-home/. 8 October, 2012. Accessed 4 May, 2015.
Dr. Pascale Michelon, “What are Cognitive Abilities and Skills, and How to Boost Them?” http://sharpbrains.com/blog/2006/12/18/what-are-cognitive-abilities/. 18 December, 2006. Accessed 5 May, 2015.
Nair, AK, et al., “Clock Drawing Test Ratings by Dementia Specialists: Interrater Reliability and Diagnostic Accuracy” The Journal of Neuropsychiatry & Clinical Neurosciences. Vol. 22: 1, pp 85-92. Winter 2010. http://neuro.psychiatryonline.org/doi/10.1176/jnp.2010.22.1.85
Tan, L, et al. “Can Clock Drawing Differentiate Alzheimer’s Disease From Other Dementias?” European Psychiatry. Vol 30: 1, pp 1434. March 2015. http://www.europsy-journal.com/article/S0924-9338(15)31108-1/abstract?cc=y=