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Who Should Use the New Diagnostic Guidelines? The Debate Continues
Introduction
Ever since new criteria came out for a research diagnosis of prodromal/preclinical Alzheimer’s disease, plus criteria for a research and clinical diagnosis of the MCI and dementia stages of the disease, they have engendered spirited discussion in the field. This revision was the first major update of AD diagnostic guidelines in more than 20 years. Alzforum covered this important milestone with commentary (see Dubois et al., 2007), in the news (see ARF related conference story), and in a Webinar with some of the developers of an international and a U.S. set of criteria (see ARF Webinar). However, conversation in the research and clinical community is far from over.
One particular question concerns how these new criteria will be implemented outside of the small core of specialized dementia clinics at leading academic medical centers or federally funded Alzheimer's Disease Centers. Are the criteria useful to clinicians everywhere? Will their application radiate out appropriately from tertiary into secondary and primary care sites throughout the community? Has the time come to apply the new guidelines in those settings?
What do diagnosticians think who were not part of the expert panels that produced the guidelines? Alzforum is inviting physicians from across the country to comment on these questions. Are you already using the new guidelines? If yes, how are they working? Are they helping to diagnose patients earlier and better? If no, what other guidance would you like to see?
This discussion arose from concerns previously articulated by Allen Frances of Duke University, Raleigh, North Carolina. Frances chaired the DSM-IV Task Force when it revised diagnostic guidelines for a wide range of psychiatric diseases. In essence, Frances cautions Alzforum readers that the guidelines “can be misused in less skilled, less careful, and less scrupulous hands.” Read Frances’ full comment to set the stage for this conversation.
Alzforum editors invited Andrew Budson at the VA Boston Health Care System and Paul Solomon at the Memory Clinic in Bennington, Vermont, to start further conversation on the questions. Both are experienced dementia diagnosticians. They did not participate in the National Institute on Aging/Alzheimer's Association or International Working Group panels that drew up the new criteria. Besides seeing patients every week, they published a guidebook in 2011 on differential diagnosis of dementing illnesses (see Alzforum Book Review). Budson and Solomon address Frances’ concerns, and then offer detailed guidance on how clinics in a variety of settings can implement the new criteria. We continue the discussion with commentary from clinicians in different cities and settings. Do you see aging patients in primary care? As a secondary care specialist? In tertiary care? What is your experience with the new guidelines? Submit a comment at the bottom of this page.
View Comments By:
- Andrew E. Budson, Paul R. Solomon — Posted 10 January 2012
- Ranjan Duara — Posted 11 January 2012
- Joel Ross — Posted 12 January 2012
Comment by: Andrew E. Budson, Paul R. Solomon
Posted 10 January 2012
Using the New Diagnostic Criteria for Alzheimer’s Disease and Mild Cognitive Impairment in Clinical Practice
We would like to comment on the usefulness in clinical practice now, and as we anticipate it in the future, of the new diagnostic criteria from the National Institute on Aging (NIA) and the Alzheimer’s Association (AA) that were published earlier this year (1,3,4). These criteria updated the prior 1984 criteria by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association work group. A number of factors have changed since 1984, prompting the development of new criteria. These factors include:
- That the AD pathophysiological process likely starts years prior to cognitive changes and decades prior to the onset of clinical dementia (2). The concept of the “AD pathophysiological process” is thus separated from “AD dementia.”
- Many patients whose cognition is not normal for their age do not meet criteria for dementia.
- Genetics of AD are better understood.
- Biomarkers of AD are available in some centers.
- New criteria are needed for research.
- Specific treatments for the AD pathophysiological process are being developed; it is therefore critical to know if patients have that process.
The new criteria define three stages of AD:
- Preclinical AD is characterized by measureable changes in biomarkers and poor performance on challenging cognitive tests.
- MCI due to AD is characterized by the first clinical changes. Mild changes in memory and other cognitive abilities are noticeable to patients and families, and can be detected through careful evaluation, but do not interfere with day-to-day activities.
- Dementia due to AD is characterized by changes in two or more aspects of cognition and behavior that interfere with function in everyday life.
Questions have been raised regarding the utility of these new criteria for clinical practice, in particular, for MCI due to AD. We do find these criteria useful in current clinical practice, and expect that they will be more useful in the future. The specific areas in which we find them useful include:
- Reminding clinicians that, because of the aging population, numbers of patients with all stages of AD will likely triple in the next 50 years.
- Helping clinicians to recognize that AD is the end of a long process, spanning years or perhaps decades.
- Talking with patients and families regarding the difference between the AD pathophysiological process versus AD dementia.
- Evaluating patients with cognitive impairment and dementia to determine etiology, with special attention to amnestic and non-amnestic presentations of AD.
- Considering biomarkers in the diagnosis of all stages of AD. Our current recommendations are to use biomarkers for those cases that present diagnostic quandaries (2).
- Enabling clinicians to diagnose (and perhaps treat) AD at the earliest possible stage. At present, that is MCI due to AD, but eventually (with new disease-modifying medications), it may be preclinical AD.
- Helping primary care providers, community practicing psychiatrists, psychologists, neurologists, geriatricians, and others understand better what to do with the new diagnostic markers being developed when they become available.
There are, however, a number of situations in which we would not use the new criteria and the tests they invoke. These situations are those in which we may detect AD pathology at an asymptomatic state and be unable to offer any treatment options. Because there are no FDA-approved treatments that have been proven to alter the underlying AD pathophysiological process, we do not currently use the preclinical AD criteria in a clinical setting. For example, we would not obtain PET amyloid imaging or CSF Aβ and tau in asymptomatic individuals, regardless of their family history or concern that they may develop the disease in the future. Because these tests—particularly the PET amyloid imaging—may detect disease pathology a decade prior to clinical symptoms, we would not use them in asymptomatic patients until disease-modifying treatments are available.
We understand the concerns raised by Dr. Frances in his comment, but disagree that we should wait for additional experts to weigh in and cost-allocation studies to be performed prior to the new criteria being used by practicing clinicians. Although these new criteria are not perfect, they represent a much-needed step forward in linking the scientific discoveries over the last 25+ years with clinical practice. Once these new criteria are operationalized, additional studies can examine the important concerns raised by Dr. Frances such as test utilization and resource allocation. Moreover, given that we are on the edge of an approaching epidemic of new cases of AD, and given that a crucial aspect of managing this disease will be early detection using biomarkers and early treatment with disease-modifying compounds, waiting any longer for more contemporary criteria that herald state-of-the-art diagnosis and treatment may not be the most productive approach.
Rather, we suggest that it would be beneficial to embrace the new criteria as a harbinger of what day-to-day practice might encompass in the near future. This goal is best accomplished if practitioners become familiar with the new criteria and use them as a roadmap for the future of diagnosis. For example, although the new criteria are explicit in stating that the use of biomarkers is not now appropriate for diagnosis, CSF biomarkers are already commercially available for use and can be helpful in certain diagnostic circumstances (2), and a PET-based amyloid imaging marker has been submitted to the FDA for approval and could be widely available in the next few years. Additionally, there are multiple disease-modifying medications in clinical trials. Data from several of these new compounds could be submitted to the FDA within the next few years, raising the possibility that these treatments could be clinically available before the additional information that Dr. Frances would like is available. Given these possibilities regarding both diagnosis and treatment, we may not have the luxury of waiting for the new diagnostic guidelines to be perfected.
Below we share our views on how we use these criteria in current clinical practice in our respective centers. We also discuss our use of the new criteria in more detail elsewhere (2).
Table 1 presents several biomarkers of Aβ deposition or neurodegeneration that are currently in use in clinical or research settings. In clinical practice, we tend to divide the biomarkers by how they are obtained: structural MRI, PET, and CSF studies.
Table 1: Putative Biomarkers for the AD Pathophysiologic Process Currently Being Used
1. Markers of amyloid-beta (Aβ) protein deposition in the brain
a) low CSF Aβ42
b) positive PET amyloid imaging
2. Markers of downstream neurodegeneration
a) elevated cerebrospinal fluid tau (total and phosphorylated)
b) decreased metabolism in temporal and parietal cortex on
[18]flurodeoxyglucose (FDG) positron emission tomography
c) atrophy on MRI in temporal (medial, basal, and lateral) and medial
parietal cortex
While volumetric MRI analyses are not routinely available, we encourage all clinicians to look for qualitative patterns of atrophy in temporal (medial, basal, and lateral) and medial parietal cortex (2).
Decreased metabolism may be observed on FDG PET scans in temporal and parietal cortex when the AD pathophysiological process has caused neurodegeneration (2). These studies are available to the clinician now, and are covered by Medicare in the United States. Note that we do not recommend using these scans routinely when the history, physical examination, cognitive testing, and structural imaging are all consistent with AD—it simply is not necessary (2). However, in situations in which one suspects an atypical neurodegenerative disease or the patient is younger than 66 years of age (when the prevalence of AD is similar to that of many other etiologies), an FDG PET scan can help distinguish AD from another disorder (such as dementia with Lewy bodies or frontotemporal dementia).
Available CSF biomarkers for AD are Aβ42, total tau, and p-tau. When all three markers are combined, the accuracy of the diagnosis is highest, with sensitivity and specificity of 85-90 percent. As in the case of FDG PET scans, we view these tests as helpful in situations in which one suspects an atypical neurodegenerative disease or the patient is younger than 66 years of age; we do not believe obtaining CSF is necessary for routine clinical practice.
Table 2 shows how we have operationalized the criteria for MCI due to the AD pathophysiological process. Following Albert et al. (3), we first present criteria for the clinical and cognitive syndrome of MCI, then criteria regarding the etiology of the MCI syndrome being consistent with AD.
Table 2: Clinical and Cognitive Evaluation for MCI Due to AD
Step 1: Establish clinical and cognitive criteria: Determine that the clinical and cognitive syndrome is consistent with MCI and the patient is not demented
Guideline | Procedures |
Concern regarding a change in cognition | History & Observation
|
Objective evidence of impairment in one of more areas of cognition (e.g., memory, attention, language, visuospatial skills, executive function) | Neurocognitive Testing
|
Preservation of independence in functional abilities | History, Questionnaires
|
Not demented | History, Observation, Questionnaires
|
Step 2: Examine etiology of MCI consistent with AD pathophysiological process: Determine the likely primary cause of signs & symptoms
Guideline | Procedures |
Rule out other possible causes of cognitive decline. Possibilities include: vascular, Lewy body other degenerative disease, traumatic, depression, medical comorbidities, mixed dementia, other (see Budson & Solomon [2] for complete list & description of the various disorders). | History, neurocognitive testing, imaging, & laboratory studies
|
Provide evidence of longitudinal decline in cognition | History, serial neuropsych testing
|
Report history consistent with AD genetic factors | Genotyping
|
Evaluate for atrophy of temporal (medial, basal, and lateral) and medial parietal cortex and other biomarkers when available and clinically useful. | Biomarkers
|
Table 3 shows how we have operationalized the new criteria for AD using a four-step approach (4). Step 1 determines dementia is present, Step 2 determines that the dementia is due to AD, Step 3 provides an increased level of certainty to the diagnosis, and Step 4 evaluates the biomarker probability of AD etiology. Finally, Tables 4 and 5 show criteria for possible AD and for dementia unlikely to be AD, respectively (4).
Table 3: Clinical and Cognitive Evaluation for All Cause Dementia and AD
Step 1: Criteria for “All Cause Dementia”
Guideline | Procedures |
|
History & observation
|
Presence of cognitive impairment | History, observation, neuropsychological testing
|
The cognitive or behavioral impairment involves a minimum of two domains | History, observation, neuropsychological testing
|
The cognitive or behavioral impairment involves a minimum of two domains. | History, observation, neuropsychological testing
|
Difference between MCI and dementia | History & observation
|
Step 2: Criteria for “Probable AD Dementia”
Guideline | Procedures |
Meets criteria for dementia | See criteria above for dementia, Step 1. |
Insidious onset – symptoms have a gradual onset over months or years, not sudden over hours or days. | History
|
Clear-cut history of worsening of cognition | History, serial neuropsych testing
|
Initial cognitive deficits are evident and most prominent in one of the following categories:
|
History, neuropsychological testing
Amnestic Presentation:
Non-amnestic presentations:
|
Do not make diagnosis of AD when there is evidence of another dementing illness. | History, neuropsychological testing, imaging studies, laboratory studies
Disorders to rule out include:
|
Note: patients who would have met criteria under the 1984 guidelines would also meet criteria under the current guidelines.
Step 3: Criteria for “Probable AD Dementia with increased level of certainty”
Guideline | Procedures |
Meets criteria for AD dementia | See above, Step 2. |
Probable AD dementia with documented decline | History, serial neuropsych testing
Evidence of progressive cognitive decline on subsequent evaluations from:
|
Probable AD dementia in a carrier of a causative AD genetic mutation | Laboratory studies
Presence of early-onset familial mutation
(Note that the apolipoprotein E ε4 allele was not considered specific enough to meet criteria.) |
Step 4: Evaluate the “Biomarker probability of AD etiology”
Guideline | Procedures |
Evaluate for atrophy of temporal (medial, basal, and lateral) and medial parietal cortex and other biomarkers when available and clinically useful. | Biomarkers
|
Table 4: Clinical and Cognitive Evaluation for Possible AD
Criteria for “Possible AD Dementia”
Guideline | Procedures |
Atypical course | History, neuropsychological testing, imaging studies, laboratory studies
Meets the core clinical criteria in terms of the nature of the cognitive deficits for AD dementia, but either
|
Etiologically mixed presentation | History, neuropsychological testing, imaging studies, laboratory studies
Meets all core clinical criteria for AD dementia but has evidence of
|
Table 5: Criteria for Dementia Unlikely to be Due to AD
1. Does not meet clinical criteria for AD dementia
2. Regardless of meeting clinical criteria for probable or possible AD dementia
a) There is sufficient evidence for an alternative diagnosis such as
HIV dementia, dementia of Huntington’s disease, or others
that rarely overlap with AD
b) Biomarkers for both Aβ and neuronal degeneration are negative.
(Adapted from McKhann et al. [4])
References
1. Sperling RA, Aisen PS, Beckett LA, et al. Toward defining the preclinical stages of Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease. Alzheimers Dement. 2011; May;7(3):280-92. Abstract
2. Budson & Solomon. Memory Loss: A Practical Guide for Clinicians, Philadelphia: Elsevier Inc., 2011. See Alzforum Book Review.
3. Albert M, DeKosky ST, Dickson D, et al. The diagnosis of mild cognitive impairment due to Alzheimer’s disease: report of the National Institute on Aging and the Alzheimer’s Association workgroup. Alzheimers Dement 2011; May;7(3):270-9. Abstract
4. McKhann GM, Knopman DS, Chertkow H, et al. The diagnosis of dementia due to Alzheimer’s disease: recommendations from the National Institute on Aging and the Alzheimer’s Association workgroup. Alzheimers Dement 2011; May;7(3):263-9. Abstract
Comment by: Ranjan Duara
Posted 11 January 2012
I appreciate the opportunity to contribute to this very important ongoing discussion regarding the definition and the diagnosis of the pre-dementia stages of AD. My goal as a clinician working exclusively in the field of dementia and its predecessors (presymptomatic, preclinical, preMCI, MCI, stages) is to present my perspective regarding the utility of the two criteria that are on the table, namely, the IWG and NIA-AA criteria. The development of both IWG and NIA-AA criteria appear to have helped better conceptualize the disease process and understand its biology in the various pre-dementia stages of Alzheimer's disease. In this respect, NIA-AA criteria, in particular, breaks new ground by rank-ordering the biomarkers and including both memory and non-memory cognitive impairment in its criteria for MCI due to AD. The contribution of IWG criteria is to present possible diagnostic methods that should be simpler and therefore easier to implement.
From a more practical standpoint, how have these new criteria helped us? During this last quarter-century there have been many advances in defining and understanding the clinical syndrome of AD and in developing various biomarkers to help diagnose the disease. Nevertheless, it would appear that 25 years after development of NINCDS-ADRDA criteria for AD, neither IWG nor NIA-AA criteria, as currently formulated, provide the means for making the diagnosis of pre-dementia AD with reasonable accuracy, nor do they instruct the clinician how to improve the accuracy of the diagnosis of probable AD. Instead, the goal in both criteria appears to be to provide the framework for future implementation of biomarkers, so as to improve the accuracy of the diagnosis and allow a more scientific basis for assessing progression of the disease and response to treatment.
The NIA-AA criteria make no attempt to incorporate biomarkers into the diagnosis of pre-dementia AD, other than for research use. The IWG criteria appear to head in the direction of incorporating the use of biomarkers for the routine clinical diagnosis of prodromal AD, but then fall short. I do believe that both sets of criteria are deficient because they have missed the opportunity to provide a protocol for the classification of pre-dementia AD, incorporating biomarkers which are widely available for use in everyday clinical practice, both at academic and tertiary care settings as well as in the community. I am referring, of course, to structural MRI, which is currently used mainly for excluding causes other than AD in the evaluation of patients with dementia, MCI, and even subjective cognitive impairment.
It is well known that the severity of medial temporal atrophy on structural MRI scans correlates strongly with the pathological severity of AD and can be used to support the diagnosis of a degenerative dementia, especially AD, regardless of the clinical stage of the disease. In research settings, the assessment of medial temporal atrophy has been confined largely to assessing hippocampal volumes, which is amenable to fairly reliable volumetric quantification. However, volumetric assessment is currently labor intensive, expensive, and not readily available in the community setting, whereas visual rating is highly accessible, quick, and inexpensive (in time and labor). The pathology of AD commences in the entorhinal cortex where atrophy usually precedes volume loss in adjacent medial temporal structures, including the hippocampus and the perirhinal cortex.
With an adaptation of the Scheltens’ visual rating method, a separate assessment of the severity of atrophy in the entorhinal and perirhinal cortex and the hippocampus is readily feasible. Inter- and intra-rater reliability is high, and radiologists will easily learn the method and read the scans accurately, especially if the ordering clinician emphasizes that getting this rating is the main reason for ordering the MRI scan. For visual rating, the MRI scans should ideally be obtained using a 3D volumetric sequence, which will provide thinly sliced serial coronal slices (i.e., a dementia sequence). This allows thinly sliced T2 weighted coronal slices to be obtained, so as to make visual rating sufficiently accurate to compensate for the fact that the scale is semi-quantitative and non-automated. Independent rating of these three structures, rather than only the hippocampus, increases the sensitivity of visual rating and makes it at least equivalent, if not superior, to hippocampal volumetry. Whereas hippocampal volume loss occurs for a variety of reasons, the pattern of atrophy of these three structures may turn out to be a signature of the disease, readily recognizable by a clinician or a radiologist.
In summary, I was hoping that new criteria for AD would break new ground, which they have done, but would also include the use of structural MRI inclusively for making the diagnosis. Although the latter did not occur, there is room for revision of both criteria so as to make both sets of criteria more useful for the clinician. The inclusion of structural MRI in these criteria would improve the accuracy of the diagnosis of probable AD, prodromal AD, and MCI due to AD. Especially in clinical trials, but also in clinical practice, a sizable cohort of patients who have non-AD diagnoses would be excluded from studies if they are found not to have medial temporal atrophy—and that would be very helpful for assessing responses to treatment.
Comment by: Joel Ross
Posted 12 January 2012
These latest criteria are very useful to me as a geriatrician as well as a researcher conducting Phase 2 and 3 MCI/Alzheimer's disease/dementia due to Alzheimer's disease clinical trials.
Patients who come to my office for memory evaluation can now have a better understanding of the continuum of neurological damage that occurs in high-risk individuals diagnosed with MCI. I can now better explain to those with amnestic MCI if they are at high risk or low risk to progress to possible dementia. I do this by allowing them to consider undergoing testing with ApoE4, CSF for levels of tau and amyloid species (both of which unfortunately are not covered by insurance), as well as PET FDG.
These three biomarkers are powerful tools that help me and my patients better understand their condition more than their results on a battery of both simple (MMSE, MOCA) and complex neuropsychological tests.
I have found these new criteria of presymptomatic (not yet incorporated into my practice, of course) MCI due to Alzheimer's disease and dementia due to Alzheimer's disease very helpful, and will continue to embrace them in the future.
References
News Citations
- Noisy Response Greets Revised Diagnostic Criteria for AD
- Book Review: Memory Loss—A Practical Guide for Clinicians
Webinar Citations
- Two New Sets of Diagnostic Criteria—Which Is Right for Your Clinic?
- Who Should Use the New Diagnostic Guidelines? The Debate Continues
Paper Citations
- Dubois B, Feldman HH, Jacova C, Dekosky ST, Barberger-Gateau P, Cummings J, Delacourte A, Galasko D, Gauthier S, Jicha G, Meguro K, O'brien J, Pasquier F, Robert P, Rossor M, Salloway S, Stern Y, Visser PJ, Scheltens P. Research criteria for the diagnosis of Alzheimer's disease: revising the NINCDS-ADRDA criteria. Lancet Neurol. 2007 Aug;6(8):734-46. PubMed.
- Sperling RA, Aisen PS, Beckett LA, Bennett DA, Craft S, Fagan AM, Iwatsubo T, Jack CR Jr, Kaye J, Montine TJ, Park DC, Reiman EM, Rowe CC, Siemers E, Stern Y, Yaffe K, Carrillo MC, Thies B, Morrison-Bogorad M, Wagster MV, Phelps CH. Toward defining the preclinical stages of Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease. Alzheimers Dement. 2011 May;7(3):280-92. Epub 2011 Apr 21 PubMed.
- Albert MS, DeKosky ST, Dickson D, Dubois B, Feldman HH, Fox NC, Gamst A, Holtzman DM, Jagust WJ, Petersen RC, Snyder PJ, Carrillo MC, Thies B, Phelps CH. The diagnosis of mild cognitive impairment due to Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease. Alzheimers Dement. 2011 May;7(3):270-9. Epub 2011 Apr 21 PubMed.
- McKhann GM, Knopman DS, Chertkow H, Hyman BT, Jack CR, Kawas CH, Klunk WE, Koroshetz WJ, Manly JJ, Mayeux R, Mohs RC, Morris JC, Rossor MN, Scheltens P, Carrillo MC, Thies B, Weintraub S, Phelps CH. The diagnosis of dementia due to Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease. Alzheimers Dement. 2011 May;7(3):263-9. PubMed.
Other Citations
External Citations
Further Reading
Papers
- de Wildt RM, Mundy CR, Gorick BD, Tomlinson IM. Antibody arrays for high-throughput screening of antibody-antigen interactions. Nat Biotechnol. 2000 Sep;18(9):989-94. PubMed.
- Irving RA, Hudson PJ. Proteins emerge from disarray. Nat Biotechnol. 2000 Sep;18(9):932-3. PubMed.
- Dubois B, Feldman HH, Jacova C, Dekosky ST, Barberger-Gateau P, Cummings J, Delacourte A, Galasko D, Gauthier S, Jicha G, Meguro K, O'brien J, Pasquier F, Robert P, Rossor M, Salloway S, Stern Y, Visser PJ, Scheltens P. Research criteria for the diagnosis of Alzheimer's disease: revising the NINCDS-ADRDA criteria. Lancet Neurol. 2007 Aug;6(8):734-46. PubMed.
- Dubois B. Interest of the new criteria for drug trials in AD. J Nutr Health Aging. 2009 Apr;13(4):356-7. PubMed.
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