Although amyloid imaging represents a promising technique in the evaluation of dementia, there are many unknowns that could impact on its diagnostic utility and therefore we recommend that its use be restricted to research at present (Level 1C; R).
Amyloid imaging is not currently approved in Canada. Should amyloid imaging become available to Canadian clinicians in the future, it must not be considered a routine test and we recommend it is regarded as an adjunct to a comprehensive evaluation for complex atypical presentations in referral to tertiary care Memory Clinics when a more accurate clinical diagnosis is needed (Grade 1B).
Should this technique become available to Canadian clinicians in the future, we recommend against its use in cognitively normal individuals or for the initial investigation of cognitive complaints (Grade 1B).
When faced with amyloid test results obtained outside Canada, physicians should be very cautious in their interpretation, i.e. used in isolation this test cannot diagnose AD, MCI, or differentiate normal from abnormal aging, and we recommend they consult with a dementia specialist familiar with this technique.
At present, there is no clinical indication for amyloid imaging in cognitively normal individuals, initial investigation of cognitive complaints, differentiating AD from other Aβ-associated dementia (e.g. DLB, CAA), differentiating between AD clinical variants (e.g., classic amnestic AD vs. PCA or lvPPA), and differentiating between non-AD causes of dementia (e.g., molecular subtypes of FTLD).
In research settings with amyloid imaging capabilities, investigators should be encouraged to develop projects that further validate the clinical and research uses of this technique and evaluate it readiness for translation to clinical care (R).
Trial designers are strongly encouraged to use this technique to: (1) decrease the heterogeneity of their MCI population; (2) identify a cohort that is likely to respond to a drug with anti-amyloid properties; and (3) study patients that are likely to convert to AD in a relatively short time frame (R).
Testing and longitudinal follow-up of asymptomatic individuals or patients with subjective cognitive impairments not meeting MCI criteria, or at-risk individuals (e.g., gene mutation carriers, family history of AD, ApoE ɛ4) should be restricted to research (R).
Future research should explore (1) the natural evolution of amyloid burden and its role in the pathophysiology of AD and other dementias, (2) its use as a potential surrogate marker for anti-amyloid therapies, (3) the value of new 18F amyloid tracers, and should (4) perform PET pathology correlations, and (5) compare amyloid imaging with CSF AD biomarkers as well as downstream markers of degeneration (R).
