Cognitive Testing: The Facts, Myths, and Value

Neuropsychological assessment guides treatment and provides hope

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Neuropsychological assessment, or cognitive testing, is the gold standard tool for measuring cognitive functions (or the “software” of the brain) such as memory, language, attention, visuospatial skills, decision-making, intellectual ability, and multitasking.

Neuropsychological assessment is also essential in determining whether cognitive changes are normal/age-related, or potentially consistent with a disorder such as mild cognitive impairment, dementia, or other conditions.

Here are a few myths and facts about neuropsychological testing that may be helpful to consider in light of recent increased dialogue and media interest in the topic.

Myth: Cognitive disorders are straightforward to diagnose based on a brief test.

Fact: Multiple tools are necessary to determine an accurate cognitive diagnosis.

When cognitive concerns or symptoms are present, multiple diagnostic tools are often used to determine a diagnosis, including a neuropsychological assessment and laboratory tests, and if indicated, neuroimaging (most commonly, a Head CT or Brain MRI).

Lab/blood tests can help determine if there are any potentially reversible contributors to cognitive symptoms, such as abnormalities in thyroid levels and Vitamin B12, among others, whereas a urinalysis can help to determine if a urinary tract infection could be a contributing factor. Depending on an individual's unique medical history, sometimes other tests are ordered (i.e., kidney and liver tests, among others).

Neuroimaging is often used to determine if there are any "structural abnormalities" that could be contributing to cognitive symptoms, such as a stroke or a tumor. It is a common misperception that dementia or other cognitive disorders can be diagnosed with neuroimaging alone. However, this is not possible, given that neuroimaging does not measure cognitive functioning (i.e., the "software" of the brain), but instead measures brain structure (which can be loosely contrasted as the "hardware" of the brain), and a diagnosis of a neurocognitive disorder such as dementia or mild cognitive impairment requires evidence of cognitive decline compared to an individual's pre-existing "baseline" level.

Of the available tools, neuropsychological testing is the only direct measure of cognitive functioning, and is as valid and reliable as blood tests and neuroimaging. In other words, labs and neuroimaging can help assess potential contributing factors to cognitive abnormalities, but in and of themselves do not measure cognitive functioning.

It is worth noting that if there is a pattern of gradual-onset, worsening memory problems over a period of years that has compromised daily independent functioning, it is less likely that the condition is solely reversible (though there may be superimposed reversible contributing factors) or solely related to a structural issue, and more important to rule out an underlying neurodegenerative/progressive cognitive disorder such as Alzheimer's disease (which causes approximately 70% of all dementia), or another neurodegenerative dementia (e.g., Lewy Body Dementia, Frontotemporal Dementia, Mixed Dementia, etc.).

One Test Score Alone is Insufficient for Diagnosis

Together, the use of multiple tools and the process of gathering multiple pieces of clinical data is referred to as an assessment (as opposed to a test, which implies that a single measure is being analyzed, which is less diagnostically accurate than analyzing the multiple measures an assessment requires).

A single test score (such as the score on a brief cognitive test) should never be interpreted in isolation, but should always be interpreted within the context of other measures, and in the context of an individual’s unique medical history. This is especially important because the same score on any given test can be interpreted very differently from person to person, and interpretation will vary as a function of that person’s age, education level, previous level of functioning, background, and other variables.

Caution about Using Popular Brief Cognitive Tests

Brief cognitive tests such as the Montreal Cognitive Assessment (MoCA) or Mini-Mental Status Examination (MMSE) cannot provide a diagnosis in and of themselves, given that a multi-component assessment is necessary to formulate an accurate diagnosis. At best, brief tools can provide starting data to inform whether a more comprehensive assessment is necessary.

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However, in individuals with higher levels of historic functioning (that is, with higher levels of education and/or high-level occupations), a brief measure may not detect cognitive abnormalities that could be detected with more comprehensive cognitive testing. Thus, an individual who obtains a perfect score on a brief cognitive measure, but has exhibited relative cognitive decline in daily life would also benefit from a more rigorous neuropsychological assessment.

In the field of neuropsychology, it is unfortunately common to see individuals who have scored “within normal limits” on brief cognitive measures, but who show diagnosable cognitive impairment during a one- to two-hour battery in which more sensitive tests are used.

The good news is that if a neurocognitive disorder is diagnosed early, an individual is often able to slow down the process of future cognitive decline with a combination of lifestyle and medical interventions. However, if they don’t know they have an abnormality, due to relying on brief cognitive tests that are interpreted as “normal,” they may lose valuable time in slowing future cognitive decline. I have seen this occur one too many times, and it is heartbreaking.

Myth: A neuropsychological assessment involves only the administration of cognitive tests.

Fact: A neuropsychological assessment is a diagnostic evaluation that involves multiple components including:

Accurate cognitive diagnosis requires multiple pieces of diagnostic data

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1. A confidential clinical interview with the individual who has cognitive symptoms or concerns, and a loved one (or “informant”) who reports their observations, especially regarding the type(s) of cognitive symptoms noted, the timing of when symptoms began, and the pattern of symptoms over time (for example, are the symptoms getting worse, better, fluctuating, staying the same?). Involving an informant is crucial given that an individual with cognitive symptoms may or may not be aware of their cognitive changes and may or may not be able to recall the timeline, pattern, and functional impact of their symptoms. The clinical interview typically lasts 45-60 minutes.
2. Administration of standardized cognitive tests. Specific tests are selected by the neuropsychologist based on the individual’s age, educational level, symptoms, and ability to engage in testing. For most older adults with memory symptoms, testing is typically completed within 1-2 hours.
3. Points 1 and 2 above are analyzed in the context of:
   (a) the individual’s medical history
   (b) with consideration of variables that may affect the accuracy of test data (for example, engagement in the testing process, emotional status), as well as behavioral observations gathered during testing, and
   (c) in the context of other diagnostic data (including any neuroimaging data and lab data) to arrive at a diagnosis

Neuropsychological assessment is crucial not only for diagnosis, but for gathering information to develop a personalized treatment plan that leverages an individual’s strengths and provides strategies to slow down future cognitive decline, compensate for cognitive challenges, and maximize quality of life.

There is a wealth of optimistic data on the value of exercise, nutrition, cognitive engagement, stress reduction, high quality sleep, and social activity in slowing down not only normal age-related cognitive changes but also slowing the rate of future cognitive decline in conditions such as mild cognitive impairment and dementia (including dementia caused by Alzheimer’s disease). An accurate diagnosis is the first step to creating a plan to maximize future functioning and can provide valuable guidance and hope.