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Tests Used to Diagnose Alzheimer’s Are Biased and Often Inaccurate, Study Finds

By | November 29th, 2018

The most widely recognized diagnostic tools for dementia are often inconclusive, at best. Most, like the Mini-Cog, are available to download online and ask patients to recall an unrelated string of words: banana, sunrise and chair, for example. These tests, which take just minutes to administer, can deliver the troubling news of a dementia diagnosis and are used in clinical trials to measure cognition. But a new study has found that quick tests like these are giving misleading results across the board.

The study, printed in the journal Neurology Clinical Practice, a publication of the American Academy of Neurology, looked at three studies: the Memory Impairment Screen, a test that measures word recall; the Mini-Mental State Examination, which asks questions like “What day is it?” and also measures the ability to remember words; and Animal Naming, a test asks patients to name as many animals as possible in one minute.

They found that the tests were often inaccurate, delivering a diagnosis that wasn’t always right.

“Our study found that all three tests often give incorrect results that may wrongly conclude that a person does or does not have dementia,” said study author David Llewellyn, Ph.D., of the University of Exeter Medical School in the United Kingdom. “Each test has a different pattern of biases, so people are more likely to be misclassified by one test than another depending on factors such as their age, education and ethnicity.”

Much like standardized tests children take in schools, which have shown a cultural bias rooted in social class, race and region, dementia tests were found to have a bias related to race, education level, age and living situation.

To carry out the study, researchers gave all three tests to 824 people in the U.S. with an average age of 82. But first, they diagnosed them with dementia based on a physical exam, genetic testing for the ApoE gene, a gene which most accurately determines Alzheimer’s risk, and psychological testing, along with more extensive memory and thinking tests. Based on those tests, they determined that 35 percent had dementia and 65 percent did not.

When they then gave them the three quick tests, they found that 36 percent of participants were wrongly classified—including false positives and false negatives—by at least one of the tests. Two percent were misclassified by all three tests. On an individual test basis, 4 to 21 percent were misclassified.

Our findings show that we desperately need more accurate and less biased ways of detecting dementia swiftly in clinic.

Scientists found that depending on the test and the patients background, some tests were easier than others—even for those with dementia. One test was found to have an education bias, showing that people who were more educated could compensate for their thinking problems with a cognitive reserve. Those who did have dementia with a higher education were more likely to be mistake as not having dementia, while those with less education were more likely to be mistaken for having it. Being a race other than white also led to more false diagnoses, along with being older or living in a nursing home. All of the tests showed that a lack of input from loved ones increased the risk of mistaken diagnosis.

“Failing to detect dementia can delay access to treatment and support, whereas false alarms lead to unnecessary investigations, causing pressure on health care systems,” said Llewellyn. “Identifying people with dementia in a timely fashion is important, particularly as new methods of treatment come on stream. Our findings show that we desperately need more accurate and less biased ways of detecting dementia swiftly in clinic.”

Last year, an ongoing study found that one-third of patients diagnosed with Alzheimer’s didn’t have beta-amyloid plaques—a protein that accumulates in Alzheimer’s and is considered a biomarker of the disease. A mistaken diagnosis can lead not only to unnecessary emotional trauma, but also cause a patient to lose valuable time if they actually have a treatable disease that isn’t Alzheimer’s.

The findings align with advice from leading experts. As Dr. Bill Burke, of the Banner Alzheimer’s Institute, told Being Patient founder Deborah Kan, the best person to ask about your memory is the people closest to you.

“You could do elaborate neuropsychological testing and none of it is as effective as asking the person who really knows [you],” said Burke.



One thought on “Tests Used to Diagnose Alzheimer’s Are Biased and Often Inaccurate, Study Finds

  1. Believe our pcp uses the mini-cog, which my husband very proudly aces! I drive him to his appointments because he can no longer remember how to get there. I know he had some sort of dementia, but with no doctor’s diagnosis, he isn’t eligible for any of the meds for early-stage dementia. Four appointments and four “you’re just fine” from our doctor – I think he thinks I’m the one with a problem! Husband is in total denial so I can’t do much. Any suggestions?

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