A new study published February 6 in the Archives of Neurology, a journal of the American Medical Association, has questioned the wisdom of a new expanded definition of Mild Cognitive Impairment (MCI), a precursor stage to Alzheimer’s disease. The new expanded definition of MCI was included in the New Guidelines for diagnosis of Alzheimer’s recently issued by a working group sponsored by the National Institute on Aging and the Alzheimer’s Association (the “New Guidelines”).
The new study found that out of 17,535 individuals previously diagnosed with Alzheimer’s Dementia (before the New Guidelines), 99.8% of those previously diagnosed with “very mild Alzheimer’s Dementia” and 92.7% of those previously diagnosed with “mild Alzheimer’s Dementia” could now be reclassified as merely having “Mild Cognitive Impairment.”
In commentary, the study’s principal author, John C. Morris, MD of the Departments of Neurology, Pathology, and Immunology at Washington University School of Medicine in St. Louis, Missouri, suggests that the approach taken by the New Guidelines in their expanded definition of MCI will create additional ambiguity in diagnoses and leave greater discretion to the individual physician whether to classify a patient as having MCI or early stage Alzheimer’s.
“The elimination of the functional boundary between MCI and AD dementia means that their distinction will be based solely on the individual judgment of clinicians, resulting in nonstandard and ultimately arbitrary diagnostic approaches to MCI,” Dr. Morris writes.
Noting that studies have shown 30% to 60% of physicians already do not disclose a diagnosis of dementia to patients (while 94% of the same physicians do disclose a diagnosis of terminal cancer), Dr. Morris suggests that the ambiguity and greater physician latitude in diagnosis under the New Guidelines may lead to increased delay in delivering a diagnoses of underlying dementia to patients and their families. He notes that, “Patients and families have consistently indicated that receiving a diagnosis of dementia is very important to them to indicate that the cognitive symptoms have an identifiable cause and to plan for the future.”
The new study is published in the February 6, 2012 issue of the Archives of Neurology, a journal of the American Medical Association.
The National Institute on Aging and the Alzheimer’s Association convened a working group to update criteria used by clinicians for diagnosis of Alzheimer’s dementia and Mild Cognitive Impairment (MCI), a precursor stage of mental decline which may (but does not always) lead to Alzheimer’s. The New Guidelines containing revised diagnostic criteria for Alzheimer’s Disease and MCI were recently published by the working group. See New Guidelines for Diagnosis of Alzheimer’s.
As explained by Dr. Morris in an introduction to his new study, “The recently published revised criteria for MCI require (1) change in cognition recognized by the affected individual or observers; (2) objective impairment in 1 or more cognitive domains; (3) independence in functional activities; and (4) absence of dementia.” “Although on the surface these revised criteria conform to earlier definitions, the revised criteria operationalize “independence in functional activities” more expansively than before. For example, “mild problems” in performing daily activities such as shopping, paying bills, and cooking are permissible, as is dependency on aids or assistance to complete such activities. This interpretation of “independence in functional activities” thus has the potential to characterize some individuals who now are diagnosed with very mild and mild AD dementia as having MCI.”
Dr. Morris undertook the new study to test the extent to which actual previous diagnoses of very mild or mild Alzheimer’s could now be re-classified as MCI under the New Guidelines.
Dr. Morris and his team examined the diagnoses previously made (before publication of the New Guidelines) of 17,535 individuals enrolled at federally funded Alzheimer’s Disease Clinics, based on clinical and cognitive data maintained by the National Alzheimer’s Coordinating Center (NACC).
They reviewed the previously determined degree of functional impairment as assessed by 2 ratings of activities of daily living, the Functional Activities Questionnaire (FAQ) and the Clinical Dementia Rating (CDR), for participants with MCI and for participants with very mild and mild AD dementia.
The researchers then interpreted these functional ratings in accordance with the revised criteria for MCI of “independence in functional activities” contained in the New Guidelines, to examine the extent to which application of the new criteria could change the current diagnoses for these individuals.
The results of the analysis found that “Almost all (99.8%) individuals currently diagnosed with very mild AD dementia and the large majority (92.7%) of those diagnosed with mild AD dementia could be reclassified as having MCI with the revised criteria, based on their level of impairment in the Clinical Dementia Rating domains for performance of instrumental activities of daily living in the community and at home.”
Furthermore, “Large percentages of these individuals with [full] AD dementia also meet the revised “functional independence” criterion for MCI as measured by the Functional Assessment Questionnaire,” Dr. Morris found.
Why does this matter? Dr. Morris says, “The elimination of the functional boundary between MCI and AD dementia means that their distinction will be based solely on the individual judgment of clinicians, resulting in nonstandard and ultimately arbitrary diagnostic approaches to MCI. This recalibration of MCI moves its focus away from the earliest stages of cognitive decline, confounds clinical trials of individuals with MCI where progression to AD dementia is an outcome, and complicates diagnostic decisions and research comparisons with legacy data.”
Moreover, introducing ambiguity into the diagnostic criteria separating MCI from Alzheimer’s which leaves so much additional discretion to the individual physician, may further discourage communication of early Alzheimer’s diagnoses to patients and their families. Dr. Morris notes that “Some studies report that between 30% and 60% of physicians do not disclose the diagnosis of dementia, much less “MCI due to AD,” to their patients, although more than 94% of the same physicians disclosed a diagnosis of terminal cancer.” He references studies reporting that physicians have cited “concern about provoking psychological distress in patients and families” as a reason for not disclosing a dementia diagnosis to them.
Nevertheless, “Patients and families have consistently indicated that receiving a diagnosis of dementia is very important to them to indicate that the cognitive symptoms have an identifiable cause and to plan for the future,” Dr. Morris writes. He also references other studies finding that depressive symptoms and measures of stress did not worsen after disclosure of a diagnosis of Alzheimer’s, and in fact improved for both the patients and their family members.
Dr. Morris advocates for implementing a recommendation included with the New Guidelines that the diagnosis be stated as “MCI due to AD [Alzheimer's Dementia]” when the clinician determines that the underlying cause of the mild cognitive impairment is Alzheimer’s, even if the patient does not yet come within the definition of Alzheimer’s under the new criteria.
“The revised criteria for MCI laudably recommend an etiologic diagnosis, “MCI due to AD,” when the clinical judgment is that AD is responsible for the cognitive dysfunction,” Dr. Morris writes. “The National Institute on Aging and the Alzheimer’s Association work group also suggests that diagnostic confidence for AD could be enhanced by using biomarkers for amyloid-β deposition and neuronal injury,” he notes.
“Some clinicians, however, are reluctant to diagnose symptomatic AD in this situation, presumably because of uncertainty as to whether “MCI due to AD” will progress to AD dementia and because the diagnosis of AD is perceived as stigmatizing,” the author notes.
However, he suggests that using an “informant-based diagnostic method” – relying on reports of family members and caregivers – can help determine the extent of “decline from the [patient's] previously attained abilities” which, he says, is key to accurately identifying individuals “in the MCI stage who have underlying AD.” Use of other AD biomarkers can also improve diagnostic certainty, he points out.
Dr. Morris urges that clinicians adopt a practice of providing an early diagnosis of Alzheimer’s as the underlying cause of MCI, where warranted, similar to current practices for other neurodegenerative diseases.
“An early etiologic diagnosis is advocated for other devastating neurodegenerative diseases such as amyotrophic lateral sclerosis, without resorting to terms such as minimal motor impairment and thus allows patients and families to initiate planning to cope with the illness and enable therapeutic interventions early in the disease course. An analogous approach should be implemented for AD.”
“The pathobiologically based “next step” now is to transition from the syndromic label of “MCI” to its etiologic diagnosis [in other words, "MCI due to AD"] when the responsible disorder is believed to be AD,” Dr. Morris writes.
“‘MCI’ still could be used to characterize individuals who may be in the early symptomatic stages of a non-AD dementing disorder, where there is less experience in accurately determining etiology than exists for “MCI due to AD,” or when potentially reversible disorders such as cognitive dysfunction associated with medications are suspected,” he suggests.
“It now is time to advance AD patient care and research by accepting that “MCI due to AD” is more appropriately recognized as the earliest symptomatic stage of AD,” Dr. Morris concludes.
Other Practical Considerations
Dr. Morris’ study does not consider what practical implications a diagnosis of merely “Mild Cognitive Impairment” as opposed to “MCI due to Alzheimer’s” or “Mild Alzheimer’s” may have for Medicare coverage or other insurance coverage of personal care expenses for the patient.
Likewise, he does not examine whether a diagnosis of “Mild Cognitive Impairment” (under the New Guidelines) as opposed to “Mild Alzheimer’s” or “Alzheimer’s” (under the old criteria) for the same symptoms could have an impact under Internal Revenue Service guidelines on the tax deductibility of maintenance and personal care expenses paid by a family caregiver for a qualifying dependent relative.
These potential financial impacts of the wording of a diagnosis — whether “MCI,” “Mild Alzheimer’s” or “Alzheimer’s” — clearly should also be studied, and may be an important consideration for family caregivers and seniors.
For further information on the New Guidelines for diagnosing Alzheimer’s and MCI, see New Guidelines for Diagnosis of Alzheimer’s.
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