Older adults misdiagnosed as showing early signs of dementia by poor diagnostic methods

Older people may slip through the net when it comes to early treatment of dementia because the current approach to diagnosis of Mild Cognitive Impairment — an intermediate clinical state between normal aging and dementia — may be inadequate, new research shows.

A study by four US universities revealed that a traditional global method for identifying people with Mild Cognitive Impairment is too imprecise. The approach may misdiagnose normally aging adults as having Mild Cognitive impairment, and not identify subtle early warning signs of brain impairment, with the result that opportunities for early intervention and treatment of individuals at the highest risk of dementia, including Alzheimer’s, are missed.

The 10-strong research group from the VA San Diego Healthcare System; University of California; and San Diego State University; assisted by Drexel University, Philadelphia; and Boston University, report their findings in the most recent issue of the Journal of the International Neuropsychological Society (JINS), published by Cambridge University Press on behalf of the International Neuropsychological Society.

Suspecting that the current method used to assess cognitive (brain) function in older people was not sensitive enough to the wide variety of warning signs which can occur, the research group devised their own method. They then tried it out on a group of 197 healthy older people living normally in their community. They also used the traditional method on the study group and then compared the two. The conventional diagnostic tool uses typically only one measure of brain function, while the new method developed by the team uses a variety and also examines patterns of dysfunction.

The results showed that the newly developed diagnostic method picked up a variety of signs missed by the conventional method and was less likely to misdiagnose normally aging older adults than the conventional method. This means that the research team has been able to make an important breakthrough by identifying two new categories of signs of possible early-onset types of dementia. These would have been overlooked by the traditional diagnostic tool. Additionally, it means that the newer method was more cautious and made less false positive errors — in other words, diagnosed fewer people who are normally aging as having brain impairment.

The researchers say they can now offer four categories of warning signs to assist diagnosis:

  • Amnestic: showing possible early symptoms of Alzheimer’s disease
  • Mixed: showing possible advanced stages of Mild Cognitive Impairment (MCI)
  • Dys-executive: showing dysfunction in activities like planning, abstract thinking, and behavior control
  • Visuo-spatial: showing problems with spatial awareness such as judging distance and depth perception

The traditional method was able to offer only the first two of the categories above.

The study’s lead author, Lindsay Clark from San Diego State University and the University of California’s Clinical Psychology doctoral program, said the new approach provided a more reliable method of identifying subtle signs, leading to much earlier treatment of a range of dementias and age-related brain dysfunction:

“The fact that the traditional criteria produced results that classified individuals as having early signs of problems whom our new diagnostic method found to have normal cognitive function is concerning. As these criteria are in widespread use among researchers, they may inaccurately diagnose normal older adults with mild cognitive impairment while preventing accurate identification of many subtle symptoms that, if treated early, could delay the development of various forms of dementia in older people, offering them an improved quality of life for longer.”

With Alzheimer’s, one of the most widespread and most feared, brain diseases, early diagnosis is absolutely crucial, adds senior author Mark Bondi from the VA San Diego Healthcare System and University of California’s Department of Psychiatry:

“One of the most important goals of the coming decade will be to identify the earliest, most reliable and most easily obtainable markers of Alzheimer’s disease, because early identification now represents the most promising window for early intervention and treatment.”

The new diagnosis method, called “comprehensive criteria for Mild Cognitive Impairment” was originally described in a publication by Amy Jak, Mark Bondi, Lisa Delano-Wood, and colleagues (2009) and is currently available for use by health professionals.

JINS Article: Are Empirically-Derived Subtypes of Mild Cognitive Impairment Consistent with Conventional Subtypes? The article is freely availabe here: http://journals.cambridge.org/JINSCLARK

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