Mild Cognitive Impairment Diagnostic Tests

MCI is diagnosed using cognitive tests, brain imaging, and blood tests.

There are at least six cognitive tests to help diagnose MCI. The two most widely used are the Montreal Cognitive Assessment (MoCA) and neuropsychological testing. The former uses such techniques as word memorization, animal identification, and copying a simple drawing. It requires only 10 to 15 minutes and can be administered in a doctor’s office.¹ Neuropsychological testing is often administered by psychologists and requires about two hours to complete.² Other tests include the Quick Mild Cognitive Impairment (QMCI), the Mini-Mental State Examination (MMSE) score, the Mini-Cog, and the Clinical Dementia Rating (CDR) Score.

Cognitive function is assessed in four cognitive categories, known as cognitive domains.³

These include:

• Executive functioning (e.g., reasoning, problem-solving, and planning)
• Language (e.g., comprehension, fluency, and semantic paraphasia [when an entire word is substituted for another word, such as saying “orange” instead of “apple” to refer to describe an apple])
• Visuospatial skills (movement, depth and distance perception, and spatial navigation – abilities needed for driving, for example)
• Attentional control (e.g., an individual’s ability to concentrate)

Brain imaging can be performed to rule out other causes of cognitive impairment like occult stroke, subdural hematoma, or brain tumor.^1,4 However, it may be of little help in making an MCI diagnosis. A specialized PET scan for amyloid deposits or slow glucose metabolism may also provide diagnostic value, but these procedures are not commonly available and are expensive.

Recently, a blood test had been reported to be promising.⁵ If these initial results can be confirmed, the test’s optimal role in detecting and classifying MCI must be established.

1. Cognitive testing. MedlinePlus website. https://medlineplus.gov/lab-tests/cognitive-testing.

2. About mild cognitive impairment. The Alzheimer’s Association website. https://www.alz.org/alzheimers-dementia/what-is-dementia/related_conditions/mild-cognitive-impairment.

3. Petersen RC, et al. Practice guideline update summary: mild cognitive impairment. Neurology. 2018;90:126-135. doi: 10.1212/WNL.0000000000004826.

4. Rosenberg PB, Lyketsos C. Mild cognitive impairment: searching for the prodome of Alzheimer’s disease. World Psychiatr. 2008;7(2):72-78. doi: 10.1002/j.2051-5545.2008.tb00159.x.

5. Palmqvist S, et al. Discriminative accuracy of plasma phosphor-tau 217 for Alzheimer disease vs other neurodegenerative disorders [published online ahead of print July 28, 2020]. JAMA. doi: 10.1001/jama.2020.12134.