The Mini-Cog© was developed to help identify, in non-specialist settings, individuals likely to have clinically significant cognitive impairment. The National Institute on Aging, the Alzheimer’s Association, the Gerontological Society of America, American Geriatrics Society, the Building Our Largest Dementia (BOLD) Center, and the Centers for Medicare and Medicaid Services all include the Mini-Cog© among valid and reliable tools that can improve detection of cognitive impairment in primary care.
It has also been widely adopted as a preferred measure for detection of cognitive impairment in clinical practice, including in the Medicare Annual Wellness Visit (AWV). Medicare has created a specific electronic medical record code to facilitate capture of data about cognitive status in administrative health data. This is a remarkable step toward developing a population-based approach to dementia care and realizing a fundamental aim of the U.S. National Plan for Alzheimer’s Disease.
Mini-Cog© was developed to help clinicians more easily identify people who might have clinically important, but unrecognized, cognitive impairment. Clinicians asked for quicker, simpler ways to screen that would fit into short primary care visits.
The initial Mini-Cog© proof of concept came from a University of Washington community study of older adults with no exposure to neurocognitive specialty providers, about half of whom were late-life immigrants of widely varying educational and ethnolinguistic backgrounds (many non-English speakers). Evidence of cognitive impairment was based on the Clinical Dementia Rating (CDR), a widely-used multi-domain assessment completed primarily as an interview with a knowledgeable partner (family or friend) and used to stage cognitive status from normal through advanced dementia.
The Mini-Cog© has two parts
It was constructed by combining 3-word recall and a clock drawing task included as an executive/cognitive composite. The initial visual algorithm for scoring, validated by receiver operating characteristics, was later replaced with an equivalent numerical system and evaluated in two population studies.
The tool includes a simple test of short-term memory, because impairment in that area is typical of the most common type of dementia in older people―Alzheimer’s disease. Clock drawing was added to the screening, because brief memory tests on their own can produce too many false positives, and many people with minor memory problems function very well.
Clock drawing tests executive functions essential to independence and self-care, relying on the coordinated use of several different cognitive skills to draw a clock that looks right and represents the correct time. Individuals without basic literacy, or those from cultures that have not kept time using analog clocks, may be cognitively normal but unable to perform that task. Substitutes for clock drawing could be tested in new versions of Mini-Cog©.
The primary validation of the Mini-Cog© was conducted in studies of accuracy in detecting the presence of dementia. Most studies included mainly individuals with Alzheimer type and mixed degenerative/vascular dementias.
The recommended cut score for dementia screening (0-2 = positive; 3-5 = negative) was derived empirically to optimize the balance of sensitivity and specificity. High specificity may be preferable to high sensitivity for screening large populations, such as older adults in health care settings; some studies, seeking higher sensitivity to subtler cognitive impairments, have used 0-3 as “positive”, but this has not been adequately tested against formal cognitive disorder diagnoses.
Individuals with mild cognitive impairment (cognitive impairment/no dementia; mild neurocognitive disorder) may be detected by the Mini-Cog© using the conventional cut score, but there is insufficient evidence to recommend the Mini-Cog© as a screen for mild cognitive impairment.
Studies conducted in primary care settings have shown that non-professionals, including medical assistants, can administer the Mini-Cog© with high reliability after minimal training and practice.