Is it Alzheimer’s or mild cognitive impairment?

Some people with mild Alzheimer’s may be reclassified as having a less serious brain disease called mild cognitive impairment, according to a new analysis of the evolving terminology.

Last year, a work group convened by the National Institute on Aging and the Alzheimer’s Assn., issued revised criteria for diagnosing mild cognitive impairment. According to this new definition, people with mild cognitive impairment still have “functional independence” and no dementia.

However, a researcher at Washington University in St. Louis sought to evaluate the impact of the revised criteria. He studied the diagnoses and neurological evaluations of 17,535 people with normal cognition, mild cognitive impairment or Alzheimer’s disease.

The study found that 99.8% of the people currently diagnosed with very mild Alzheimer’s disease and 92.7% of people currently diagnosed with mild Alzheimer’s disease would be considered as having mild cognitive impairment under the revised criteria issued last year.

The confusion seems to stem from what is meant by “functional independence.” The work group allows for a broad view of the term, meaning that mild problems performing daily activities such as shopping or paying bills or reliance on aids to help with those tasks is still considered “functionally independent.”

Traditionally, the line between what constitutes mild cognitive disorder and Alzheimer’s disease rests on whether the impairment disrupts the activities of daily living. The new criteria “now obscure this distinction,” said the author of the paper, Dr. John C. Morris.

“The revised criteria accept that MCI can be associated with impaired functional activities, such that the distinction of MCI from dementia now simply is a matter of an individual clinician’s threshold for what represents one condition versus the other,” he wrote.

The study appears online in the journal Archives of Neurology.

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