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Diagnostic Workup

Adding biomarker evidence to your existing algorithm may help increase diagnostic confidence in Alzheimer’s disease1‐6

The neuropathology of Alzheimer’s disease (AD) is defined by the presence of both amyloid plaques and neurofibrillary tangles.1,2

Major advances in AD research have included the development of biomarker tools initially with CSF, followed by PET tracers and more recently in blood, that can detect key pathologies, including amyloid and tau.1,2,4,5

PET brain scan icon

BIOMARKER PET SCANS1,4,5

  • Used to determine presence of abnormal amyloid plaque and aggregated tau NFTs
  • Provides the means to assess visual evidence of brain amyloid and tau pathology in vivo
  • Approved amyloid and tau PET scans are available for use at your discretion

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The Alzheimer’s Association and the Society of Nuclear Medicine and Molecular Imaging developed Appropriate Use Criteria (AUC) for amyloid PET scans.

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Blood test icon

BLOOD TESTS1

  • Collected via blood sample to identify the probability of presence or absence of amyloid plaques in the brain (eg, Aβ42/40 ratio)

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Cerebrospinal fluid icon

CSF TESTS1,2

  • Used to determine amyloid beta (eg, Aβ40 and Aβ42) and tau protein (eg, total tau and phosphorylated tau) levels measured in spinal fluid

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A multidisciplinary workgroup convened by the Alzheimer's Association developed AUC for the use of CSF testing for AD pathology detection in the diagnostic process.

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Diagnostic tool icon

Other routine diagnostic tools used in the assessment of patients include3,7:

  • Routine labs (such as CBC, metabolic panel, LFTs, TSH, vitamin B12, folate)
  • Structural imaging (CT scan, MRI)
  • Neuropsychological assessment
  • FDG-PET scan

Biomarker evidence of AD pathology has been shown to increase clinician confidence in diagnosing AD6,8

A comparison of diagnostic confidence pre- and post-amyloid PET scans was done in a study of patients with cognitive impairment of unknown etiology or suspected AD8

Diagnostic uncertainty 16 to 72 PET scan

Diagnostic uncertainty was reduced from 72% prior to amyloid PET to 16% post-amyloid PET scan8

Understand the impact Red external link icon

Aβ=amyloid beta; CBC=complete blood count; CSF=cerebrospinal fluid; CT=computed tomography; FDG-PET=fluorodeoxyglucose-positron emission tomography; LFT=liver function test; MRI=magnetic resonance imaging; NFT=neurofibrillary tangle; PET=positron emission tomography; TSH=thyroid-stimulating hormone.

References:

  1. McDade E, Bednar M, Brashear HR, et al. The pathway to secondary prevention of Alzheimer’s disease. Alzheimers Dement (N Y). 2020;6(1):1-9.
  2. Aisen PS, Cummings J, Jack CR. et al. On the path to 2025: understanding the Alzheimer's disease continuum. Alzheimers Res Ther. 2017;9(1): 60.
  3. Hort J, O'Brien JT, Gainotti G, et al. EFNS guidelines for the diagnosis and management of Alzheimer’s disease. Eur J Neurol. 2010;17(10):1236-1248.
  4. Grundman M, Pontecorvo MJ, Salloway SP, et al. Potential impact of amyloid imaging on diagnosis and intended management in patients with progressive cognitive decline. Alzheimer Dis Assoc Disord. 2013:27(1):4-15.
  5. Counts SE, lkonomovic MD, Mercado N, et al. Biomarkers for the early detection and progression of Alzheimer’s disease. Neurotherapeutics. 2017;14(1):35-53.
  6. McKhann GM, Knopman DS, Chertkow H, et al. 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;7(3):263-269.
  7. Albert MS, DeKosky ST, Dickson D, et al. 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;7(3):270-279.
  8. Rabinovici GD, Gatsonis C, Apgar C, et al. Association of amyloid positron emission tomography with subsequent change in clinical management among Medicare beneficiaries with mild cognitive impairment or dementia. JAMA. 2019;321(13):1286-1294.