A recent study showed a high rate of misdiagnosis of dementia when using brief cognitive screening tools. Incredibly, 35.7% of patients were incorrectly classified by at least one of the three screening procedures that were examined. The researchers looked at the well known Mini-Mental State Examination (MMSE), the Memory Impairment Screen (MIS) and animal naming (AN).

Animal Naming

Why is animal naming even considered to be a screening procedure? The task simply requires the patient to name as many animals they can think of within one minute.  How ill-considered to use a single “test” of cognitive functioning to make a diagnosis of demenia. The absurd implication is that some clinicians rely on a single test that takes a minute to administer to make a diagnosis of dementia.  It’s ridiculous.

Routine Short-Cuts

In any event, the fact of the matter is that instead of referring patients for detailed neuropsychological testing, many clinicians routinely skip that step in the investigative process when making a diagnosis of dementia. Instead, they rely on the results of a brief cognitive assessment, such as the MMSE. This research shows just how dangerous this omission can be. Misdiagnosis occurs in a third of patients when using brief screening tools.

Image of trees in the shape of a head in profile losing leaves

Misdiagnosis Rate

A very concerning finding was misdiagnosis rate in patients with subtle cognitive problems. Such patients do not actually have dementia and we use the term mild cognitive impairment (MCI) instead. Using the MMSE with MCI patients resulted in a false-positive diagnosis of dementia in 74.5% of patients. False-positive diagnoses were 82.1% for the MIS and also 82,1% for AN for patients with MCI. That’s a scary error rate.

Imagine the unnecessary alarm and fear triggered in the patients and family members by an incorrect diagnosis of dementia.  Furthermore, these false-positive errors would have led to some patients being unnecessarily started on medication (such as acetylcholine-esterase inhibitors) that they did not need. 

Solutions

The lesson is simple. Don’t take short-cuts when making a diagnosis of dementia. Detailed neuropsychological testing is mandatory in all cases of suspected dementia, not an optional extra.

 

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