Basic dementia tests often get it wrong if used alone

Posted on 28th November 2018

Neurology: Clinical Practice: Predictors of dementia misclassification when using brief cognitive assessments

Researchers in the UK have highlighted limitations of three cognitive tests that can be used to assess people for signs of dementia. The results of the study involving adults from the US are published today (27 November) in the scientific journal Neurology.

Currently 850,000 people in the UK are living with dementia, however only 63% of people to have the condition have a formal diagnosis. This can be due to several factors including difficulty diagnosing in the early stages, the slow progression and limited public awareness of the diseases that cause dementia.

In this study, researchers from the University of Exeter and the University of Edinburgh looked at 824 older adults from the US to see if three commonly used cognitive tests accurately diagnosed people with dementia. Scientists asked volunteers over the age of 70 to complete the Mini Mental State Examination (MMSE), memory impairment screen (MIS) and animal naming test (AN).

They found that out of 842 adults, 301 people were misclassified by at least one of the three assessments, however only 14 people were misclassified by all three test scores.

A misclassification of dementia occurred when the test results either indicated a person did not have dementia when they actually did or where a person who tested positive as having dementia didn’t actually have the condition.

The researchers identified a wide range of factors that predicted a misclassification, including ethnicity and level of education, yet these predictive factors tended to be different for each of the tests.

Dr Sara Imarisio, Head of Research at Alzheimer’s Research UK, said:

“This study highlights the limitations of certain brief cognitive tests of the kind that might be used by GP’s when determining whether to refer a person to a specialist memory service for a more detailed dementia assessment. It is important to also note that GPs don’t rely on these tests in isolation but will also take note of a range of other factors including a person’s medical history, if friends or family members have observed changes in their behaviour, and how well they are able to go about their daily life.

“Being able to diagnose dementia accurately is critical to provide people with the best treatment and support available.  Alzheimer’s Research UK is funding research into new ways to detect biological signs of diseases like Alzheimer’s, but as this work continues it is vital that we also refine the tools that are currently available to ensure people receive as accurate and timely a diagnosis as possible.”

Posted in Science news