Biochemical Markers of Alzheimer Disease and Dementia
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Defines coverage stance for laboratory measurement of biochemical biomarkers (CSF, plasma/serum, urine, and multianalyte assays) for diagnosis, prognosis, or management of Alzheimer disease and dementia for Blue Cross Blue Shield - Tennessee members.
No material clinical or coverage changes in this revision.
Coverage Determinations and Rationale
Not Covered Biomarker Tests
Tests that do not meet coverage criteria due to insufficient evidence:
Policy lists these four explicit categories as not meeting coverage.
Guideline-based appropriate use and predictive utility
Recommendations summarized from professional organizations and expert groups regarding appropriate use of CSF and blood biomarkers:
Derived from Shaw et al., 2018 table of indications
Derived from Shaw et al., 2018
Simonsen et al., 2017: strong recommendation for prediction but not as replacement for imaging
Jack et al., 2018; Albert et al., 2011
Measurement of biochemical biomarkers for Alzheimer disease in the following specimen types DOES NOT MEET COVERAGE CRITERIA and are explicitly excluded from coverage: (1) cerebrospinal fluid (CSF) biomarkers (e.g., tau proteins, amyloid beta peptides, α-synuclein, neural thread proteins); (2) plasma and/or serum biomarkers (e.g., tau, amyloid beta peptides, neural thread proteins, ApoE/ApoE4); (3) urinary biomarkers (e.g., neural thread proteins, amyloid beta peptides, urinary extracellular vesicle analysis); and (4) the use of multianalyte assays, algorithmic analysis, or other tests not specifically listed for diagnosis, prognosis, or management of Alzheimer disease or dementia.
Guideline authors do not advocate routine use of Alzheimer disease biomarker tests for all patients. Reasons cited include that core clinical criteria already provide good diagnostic accuracy in most patients, and that biomarker-based approaches require further study and validation. In addition, CSF biomarkers currently show large between-laboratory variability and limited availability, and some operational guidance states these measures are not approved or widely available for routine clinical use.
Routine CSF analysis is not recommended for all patients. CSF testing may be considered in select situations where the diagnosis remains uncertain or presentation is atypical — for example, patients with diagnostic uncertainty, early-onset dementia (onset <65 years), or predominant language, visuospatial, dysexecutive, or behavioral features — to help evaluate for Alzheimer disease pathophysiology.
The policy cites a number of bibliographic references and consensus documents used to inform these statements, and several of those references present guidance or evidence summaries rather than explicit payer coverage exclusions.
Consistent with the evidence review summarized in this policy, measurement of CSF, plasma/serum, and urinary biomarkers, as well as the use of multianalyte or algorithmic tests for Alzheimer disease, DO NOT MEET COVERAGE CRITERIA for diagnosis, prognosis, or management.
The American Academy of Neurology states that, as of their review, there are no accepted biomarkers for routine use to predict progression in patients with mild cognitive impairment (MCI). Clinicians should counsel patients and families that biomarkers are not established for routine prognostication and that the evidence base remains evolving.
The United States Preventive Services Task Force concluded that current evidence is insufficient to assess the balance of benefits and harms of screening for cognitive impairment in older adults, and therefore does not support routine population screening using biomarkers or other means at this time.
Several cited bibliographic entries provide background, methodological discussion, or consensus recommendations but do not themselves state explicit Not Medically Necessary or coverage-denial determinations; the policy synthesizes these sources to reach coverage conclusions.
Provider Requirements, Authorization, and Documentation
Prior Authorization for Biomarker Testing
Prior authorization may be required for biomarker testing. Note that this policy indicates CSF, plasma/serum, urine, and multianalyte/algorithmic tests for Alzheimer disease do not meet coverage criteria; providers should obtain prior authorization when required by the member's benefit plan and submit documentation supporting medical necessity and clinical context.
- Excluded tests: CSF biomarkers (tau, amyloid beta, α‑synuclein, neural thread proteins)
- Excluded tests: Plasma/serum biomarkers (tau, amyloid beta, ApoE/ApoE4, neural thread proteins)
- Excluded tests: Urinary biomarkers and extracellular vesicle analysis
- Excluded tests: Multianalyte assays/algorithmic tests
CSF Testing Indicated for Select Clinical Scenarios
CSF biomarker testing is indicated only for select clinical scenarios per specialty guidance. The Alzheimer's Association recommends CSF testing as appropriate for specific indications (eg, persistent/progressing unexplained MCI, suspected AD symptoms, early-onset onset <65, and certain SCD or high‑risk situations) and inappropriate for routine use in cognitively unimpaired individuals or certain other scenarios. Use CSF testing as an add‑on to clinical evaluation rather than as a standalone diagnostic test.
- Appropriate indications include: persistent/progressive unexplained MCI, symptoms suggestive of AD, MCI or dementia with early onset (<65), meeting core clinical criteria for probable AD with typical onset
- Inappropriate: routine testing in cognitively unimpaired individuals, APOE ɛ4 carriers without impairment, using LP solely to determine disease severity
Confirm Coverage and Prior Authorization per Government and Payer Rules
Confirm coverage and prior authorization requirements per applicable government and payer rules. If there is any conflict between this policy and an applicable government determination (LCD/NCD) or state Medicaid rule, the government policy governs the coverage decision.
- Verify Medicare LCDs/NCDs and state Medicaid policies prior to ordering
- Follow payer-specific prior authorization processes when required
Prior Authorization Not Specified in References
The references cited in this policy do not by themselves specify prior authorization procedures. Providers should not assume lack of a stated prior authorization requirement in the bibliography means prior authorization is not required by the payer or by applicable government programs.
- Bibliographic references (guidelines, systematic reviews) generally do not include payer-specific prior authorization directives
- Check the member's benefit plan and payer portals for operational prior authorization instructions
Use CSF Biomarkers Only with Clinical Context
Do not use CSF or other biomarker assays as standalone diagnostic tests. CSF biomarkers must be interpreted within the full clinical context (clinical evaluation, imaging, comorbidities) due to between‑laboratory variability and lack of universally accepted cutoffs.
- CSF Aβ1‑42 with elevated T‑tau or P‑tau supports AD pathology but must be integrated with clinical findings
- Large between‑laboratory variability and absent standard cutoffs limits standalone interpretation
Documentation Expectations
Document clinical rationale and laboratory method when ordering or submitting claims for biomarker tests. Include clinical presentation, objective testing results, specific indication (per specialty criteria), expected impact on management, and whether the assay is a laboratory‑developed test (LDT) or FDA‑cleared/approved.
- Clinical documentation: symptoms, objective cognitive testing results, differential diagnosis, and how results will influence management
- Laboratory documentation: test method, vendor/assay name, LDT status (if applicable), and quality control participation
Need for Standardization and Quality Control
Address standardization and quality control concerns: confirm that laboratories participate in quality control or standardization programs (eg, Alzheimer's Association CSF QC initiatives) and be aware of between‑laboratory variability that can affect interpretation.
- Prefer labs participating in recognized QC/standardization efforts
- Note potential variability and request method‑specific reference ranges or cutoffs
Consider Less Invasive Blood‑Based Biomarkers First
Consider using less invasive blood‑based biomarkers as an initial step in a multi‑stage diagnostic process, reserving CSF testing or PET confirmation for when blood biomarkers are positive or when additional confirmation is needed.
- Blood biomarkers can serve as first‑step screening in a multi‑stage process
- CSF or PET may be used to confirm results when clinically necessary
No Step Therapy Directives in References
There are no step‑therapy directives or required prior diagnostic steps specified in the cited references. Payers may still impose step edits or clinical prerequisites; verify payer rules before ordering.
- Guidelines/reviews do not mandate step therapy for biomarker testing
- Check the member's benefit plan for any payer‑level step edits or prerequisites
Clinical and Evidence Background
Alzheimer disease is a progressive neurodegenerative disorder characterized by cognitive decline associated with amyloid plaques and neurofibrillary tangles. Biomarkers such as CSF Aβ42, Aβ42/40 ratio, total tau, phosphorylated tau, plasma p‑tau species, neurofilament light (NfL), and other candidate measures have been studied to detect pathology, predict progression, or correlate with imaging. However, clinical utility is limited by variable sensitivity and specificity across studies, between‑laboratory variability, and lack of standardized methods; accordingly, many guideline groups recommend restricted or research‑focused use rather than routine clinical application.
Terms and Abbreviations
Billing and Code Considerations
| Measurement of cerebrospinal fluid biomarkers (e.g., tau, amyloid beta peptides, α-synuclein, neuronal thread proteins) DOES NOT MEET COVERAGE CRITERIA | |
| Measurement of plasma and/or serum biomarkers (e.g., tau, amyloid beta peptides, neural thread proteins, ApoE/ApoE4) DOES NOT MEET COVERAGE CRITERIA | |
| Measurement of urinary biomarkers (e.g., neuronal thread proteins, amyloid beta peptides, urinary extracellular vesicle analysis) DOES NOT MEET COVERAGE CRITERIA | |
| Use of multianalyte assays, algorithmic analysis, and other tests not specifically listed DOES NOT MEET COVERAGE CRITERIA |
| Alzheimer's Association: CSF biomarker testing recommended for selected clinical indications (e.g., subjective cognitive decline at increased risk, persistent/progressive unexplained MCI, symptoms suggesting possible AD, early-onset <65, meeting core clinical criteria for probable AD with typical onset) — guidance only | |
| Alzheimer's Association: CSF testing inappropriate for cognitively unimpaired individuals with normal testing and no risk, unimpaired at risk based only on family history, for determining disease severity after AD diagnosis, APOE ɛ4 carriers without impairment, and use of LP in lieu of genotyping for ADAD mutation carriers | |
| JPND BIOMARKAPD: In MCI, CSF biomarkers may be used as an add-on to clinical evaluation to predict progression to AD dementia (recommendation for predictive use, not routine clinical replacement) |
Document Revision History
Shaw et al. published Appropriate Use Criteria for lumbar puncture and CSF testing in Alzheimer's disease, providing indications and inappropriate uses informing policy guidance.
Policy cites 2018 Alzheimer's Association Appropriate Use Criteria (Shaw et al.) and incorporates recommendations limiting routine use of CSF biomarkers and specifying select clinical indications.
JPND BIOMARKAPD expert working group issued recommendations supporting use of CSF biomarkers as an add-on in MCI to predict progression, informing the policy's guidance on appropriate use.
NIA-AA guidance (original framework published 2011) describing biomarker staging for preclinical and symptomatic phases cited as foundational evidence for biomarker interpretation.
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