How the Mini-Cog Is Used to Test for Alzheimer's and Dementia

Testing for Dementia with the Mini-Cog
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The Mini-Cog is a rapid screening test for Alzheimer's disease that takes only about three minutes to administer. Unlike other popular Alzheimer's tests that measure several aspects of cognition, such as the MMSE and the MoCA, the Mini-Cog measures only two: short-term recall and clock drawing (where a person draws numbers and arms pointed at a specific time on a paper clock). Despite that, the Mini-Cog is extremely accurate at predicting whether someone has dementia.

As a screening test, however, it should not substitute for a complete diagnostic work-up.

The Mini-Cog was developed by Dr. Soo Borson, a physician who specializes in memory disorders. 

Administration of the Mini-Cog

Administration of the Mini-Cog is very simple. First, the person is asked to repeat three unrelated words, which tests immediate recall. Then, he is asked to do the clock drawing test. The clock drawing test assesses multiple factors, but its ability to screen for executive functioning is especially helpful in identifying dementia. Finally, the person is asked to remember the three words, testing their memory after the distracting task of drawing the clock.

Scoring of the Mini-Cog

Scoring of the Mini-Cog is simple as well. A person is scored as likely to have dementia if they recall none of the three words, or if they recall one or two of the three words and draw an abnormal clock.

Similarly, a person is scored as unlikely to have dementia if they recall all three words or if they recall one or two of the three words but draw a normal clock.

Usefulness of the Mini-Cog

Unlike the MMSE, the diagnostic value of the Mini-Cog is not influenced by education level or language abilities.

Sensitivity and specificity of the Mini-Cog, key properties of every screening test, are excellent. Sensitivity refers to the test's accuracy in identifying individuals with the disease (i.e., persons with Alzheimer's test as positive). Specificity refers to the test's effectiveness in identifying people who do not have the disease (i.e., persons without the disease test as negative). 

The Mini-Cog has also been shown to be helpful in predicting and identifying people with delirium, an acute condition of increased confusion. Delirium often develops after anesthesia for surgery or with an infection such as an urinary tract infection.

Overall Advantages and Disadvantages of the Mini-Cog

The Mini-Cog's advantages are many: It is fast, simple, and superior even to the MMSE in predicting dementia. It has also been shown to be effective at identifying mild cognitive impairment, a condition that sometimes, but not always, progresses to Alzheimer's disease.

There are also different versions of the Mini-Cog which allows you to choose from several sets of three words to test recall.

This can prevent repeat tests from being affected by prior administration of the test.

Unlike the MMSE which involves a fee each time the test is used, the Mini-Cog is a free test that can be used without permission for testing of individuals.

A disadvantage is that the scoring of the clock drawing test is vulnerable to different interpretations. Additionally, the mini-cog can't be used with persons who have visual impairments or difficulty with holding or using the pen or pencil.

Finally, while the mini-cog is fairly effective at identifying dementia, it doesn't provide a way to measure progression or extent of dementia. 

Sources:

Alzheimer's Association.  http://www.alz.org/documents_custom/minicog.pdf.

Borson S, Scanlan J, Brush M, et al.The Mini-Cog:'vital signs' measure for dementia screening in multi-lingual elderly.Int J Geriatr Psychiatry. 2000; 15: 1021-1027.

Velayudhan L, Ryu S-H, Raczek M, et al. Review of brief cognitive tests for patients with suspected dementia. 2014;26(8). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4071993/

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