Updated AD Guidelines Chart the Full Diagnostic Journey

New evidence–based clinical practice guidelines from the Alzheimer’s Association provide updated recommendations on evaluating individuals suspected of having Alzheimer’s disease (AD) and AD-related neurodegenerative disorders in both primary and specialty care settings.

This is the first update since 2001 for specialists and the first guideline for primary care physicians. Executive summaries of the guidelines were published in three articles online on December 23 in a special issue of Alzheimer’s & Dementia.

What’s New? 

“With this guideline, we expand the scope of prior guidelines by providing recommendations for practicing clinicians on the process from start to finish,” co-author Brad Dickerson, MD,

director of the Massachusetts General Hospital Frontotemporal Disorders Unit and professor of neurology at Harvard Medical School, Boston, said in a statement.

“If clinicians adopt these recommendations and healthcare systems provide adequate resources, outcomes should improve in most patients in most practice settings,” Dickerson added in an interview with Medscape Medical News.

Through a modified-Delphi approach and guideline-development process, an expert workgroup representing primary and specialty care reviewed 7374 publications, of which 133 met inclusion criteria.

Based on the information, the workgroup outlined a three-step patient-centered evaluation process, which includes assessing cognitive functional status, identifying the cognitive-behavioral syndrome based on specific symptoms, and determining the likely brain diseases or conditions causing the symptoms.

What Are the Key Recommendations?

The guidelines include 19 “practical” recommendations that are applicable to any practice setting. They capture the core elements of a high-quality evaluation and disclosure process, the author said. Here is a brief summary of the recommendations: 

Initial evaluation: Perform a multitiered evaluation for patients who self-report or whose care partner or clinician reports cognitive, behavioral, or functional changes.

Patient-centered communication: Partner with the patient and/or care partner to establish shared goals for the evaluation process; assess the patient’s capacity to engage in goal setting.

Diagnostic formulation: Use a tiered approach to assessments and tests based on individual presentation, risk factors, and profile, aiming to determine the level of impairment, cognitive-behavioral syndrome, and likely causes and contributing factors.

History taking: Gather reliable information from informants about changes in cognition, activities of daily living, mood, neuropsychiatric symptoms, and sensory/motor functions. Document individualized risk factors for cognitive decline.

Examination: Conduct a comprehensive examination of cognition, mood, behavior, and a dementia-focused neurologic evaluation using validated tools.

Laboratory tests: Perform tiered, individualized laboratory evaluations, starting with routine tests for all patients.

Structural imaging: Obtain structural brain imaging (MRI preferred, CT as an alternative) to help establish a cause.

Ongoing communication: Engage in ongoing dialogue with patient/care partner to guide them throughout the diagnostic process.

Diagnostic disclosure: Share findings honestly and compassionately, explaining the syndrome, its severity, probable cause, prognosis, treatment options and support resources.

Specialist referral: Refer patients with atypical, uncertain, early-onset, or rapidly progressing symptoms to a dementia subspecialist.

Neuropsychological testing: Use in instances of diagnostic uncertainty or patients with complex clinical profiles. At a minimum, the neuropsychological evaluation should include normed neuropsychological testing of the domains of learning and memory (in particular delayed free and cued recall/recognition), attention, executive function, visuospatial function, and language.

Advanced diagnostic testing: When diagnostic uncertainty remains, obtain additional laboratory tests tailored to individual patient profiles.

Molecular imaging: In a patient with an established cognitive-behavioral syndrome in whom there is continued diagnostic uncertainty regarding cause(s) after structural imaging, a dementia specialist can obtain molecular imaging with fluorodeoxyglucose positron emission tomography (PET) to improve diagnostic accuracy.

Cerebrospinal fluid (CSF) analysis: Utilize CSF biomarkers to evaluate amyloid beta and tau profiles in cases with unresolved diagnostic uncertainty.

Amyloid PET imaging: Perform amyloid PET scans for patients with persistent diagnostic uncertainty after other assessments.

Genetic counseling and testing: Consider genetic testing for patients with strong autosomal dominant family histories and involve a genetic counselor.

Future Directions?

Maria C. Carrillo, PhD, chief science officer and medical affairs lead for the Alzheimer’s Association, encourages clinicians to incorporate these guidelines into their practice.

“These guidelines are important because they guide clinicians in the evaluation of memory complaints, which could have many underlying causes. That is the necessary start for an early and accurate Alzheimer’s diagnosis,” Carrillo said in a statement.

Dickerson said the new guidelines do not address blood-based biomarkers “because nobody really feels that they are ready for prime time yet, even though they’re getting rolled out as clinical products.” 

However, the recommendations will be revised as needed. “That’s one of the values of setting this up as a process; whenever any new development occurs, it will be easy to update the guidelines to show where that new test or new biomarker fits in the overall process,” he said.

New Appropriate Use Guidance

A separate workgroup, jointly convened by the Alzheimer’s Association and the Society of Nuclear Medicine and Molecular Imaging, has revised appropriate use criteria (AUC) for amyloid PET imaging and developed AUC for tau PET imaging.

They were simultaneously published online on January 8 in Alzheimer’s & Dementia and The Journal of Nuclear Medicine. They are the first revision since the initial AUC for amyloid PET was introduced in 2013.

“The updated amyloid/tau appropriate use criteria will help ensure these tracers are used in a cost-effective manner and the scan results will be used appropriately to add value to the diagnosis and management of dementia,” workgroup members Kevin Donohoe, MD, with Beth Israel Deaconess Medical Center, Boston, and Phillip Kuo, MD, with City of Hope National Medical Center, Duarte, California, told Medscape Medical News.

The AUC include 17 real-world scenarios in which amyloid or tau PET may be considered, with the two tests considered separately and given their own rating for each scenario.

Overall, the strongest evidence for their use includes assessment and prognosis for people with mild cognitive impairment; assessment of people with dementia when the cause is not clearly known; and determining eligibility for treatment with new disease-modifying therapies, and monitoring response to these treatments, the workgroup said.

“Whereas the prior AUC was written at a time when only the deposition of amyloid could be documented, the new therapeutic agents allow us to demonstrate the actual clearance of amyloid during therapy,” Donohoe and Kuo explained.

“These new therapeutic agents are expensive and, as with most medications, may cause unwanted side effects. The most recent version of the AUC includes information about the appropriate use of amyloid imaging for both documenting the presence of amyloid deposits in the brain, making anti-amyloid therapy an option, as well as documenting the effectiveness of the therapeutic agents as amyloid is (or is not) cleared from the brain,” Donahoe and Kuo noted.

The revised AUC also state that, in most cases, amyloid and tau PET tests should not be used for people who do not have cognitive impairment, even if they carry the APOE4 risk-related gene for AD; nonmedical use such as for legal concerns, insurance coverage, or employment screening; and in place of genetic testing in patients suspected of carrying a disease-causing genetic mutation.

In a statement, lead author Gil D. Rabinovici, MD, with University of California San Francisco, emphasized that the AUC “should be considered guidelines for clinicians, not a substitute for careful clinical judgment that considers the full clinical context for each patient with cognitive complaints.”

This research was funded by the Alzheimer’s Association. Disclosures for guideline authors are available with the original articles.