Biochemical Markers of Alzheimer Disease and Dementia
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Defines coverage stance and limitations for biochemical biomarker testing (CSF, plasma/serum, urine, multianalyte assays) for diagnosis, prognosis, or management of Alzheimer disease and dementia for Blue Cross Blue Shield - Tennessee members. Specifies that coverage decisions depend on individual benefits and references Medicare/Medicaid specifications in a later section.
Policy adopted Avalon policy recommendation effective 7/1/2023.
Coverage Summary
This policy, effective 2023-07-01, addresses biochemical biomarker testing for Alzheimer disease and dementia and states that such testing is not covered (cosmetic) for the listed indications. The categories explicitly listed as not meeting coverage criteria include testing of CSF biomarkers (e.g., tau, amyloid beta peptides, α-synuclein, neural thread proteins), plasma/serum biomarkers (e.g., tau, amyloid beta peptides, ApoE/ApoE4), urine biomarkers (e.g., AD7c-NTP, amyloid peptides, urinary extracellular vesicle analysis), and the use of multianalyte/algorithmic assays for diagnosis, prognosis, or management.
Coverage decisions are dependent on an individual member's benefit plan and applicable government policy; if conflict exists with Medicare/Medicaid (LCD/NCD) or state Medicaid rules, the government policy governs determinations.
Medical Necessity and Diagnostic Criteria
Not meeting coverage criteria
The following tests DO NOT MEET COVERAGE CRITERIA due to lack of sufficient published evidence:
Explicitly listed as not meeting coverage criteria
Explicitly listed as not meeting coverage criteria
Explicitly listed as not meeting coverage criteria
Explicitly listed as not meeting coverage criteria
Definitions and evidence for in-vivo AD pathology (IWG)
The IWG describes specific biochemical evidence in their definitions of AD:
Situations where CSF analysis can be considered (guideline summaries)
Guideline-based conditional recommendations where CSF testing may be appropriate:
CCCDTD 2020
CCCDTD 2020
EFNS Level B; EFNS Good Practice Point
EFNS Good Practice Point
Provider Actions & Requirements
Benefit verification required
Application of coverage criteria is dependent upon an individual's benefit coverage at the time of the request; providers must verify member benefits and applicable Medicare/Medicaid specifications (referenced in Section VII).
- Verify member benefits and any Medicare or state Medicaid specifications referenced in Section VII before submitting requests.
Follow applicable government/local coverage
If there is a conflict between this policy and any relevant government policy (e.g., Local Coverage Determinations or National Coverage Determinations for Medicare, or state Medicaid coverage), the government policy governs determinations. Providers should reference CMS and state Medicaid coverage databases for the most up-to-date rules.
- Check LCD/NCD and applicable state Medicaid coverage databases for any conflicts or differing coverage rules.
Laboratory-developed tests (LDTs) regulatory status
Many laboratories develop specific tests that they validate and perform in-house as laboratory-developed tests (LDTs). LDTs are regulated by CMS under CLIA '88 as high-complexity tests and are not approved or cleared by the U.S. Food and Drug Administration for clinical use; labs must validate these in-house tests per CLIA requirements.
- Note that LDTs are regulated under CLIA '88 as high-complexity tests and are not FDA approved/cleared for clinical use.
Coding
| No codes listed |
| No codes listed |
Background and Evidence Summary
Alzheimer disease (AD) is a common neurodegenerative dementia with progressive cognitive decline and substantial public health burden. Biomarker research has focused on earlier detection and staging because pathological processes often precede symptoms; commonly studied markers include CSF Aβ42 (and the Aβ42/40 ratio), total and phosphorylated tau, and other CSF proteins that may reflect neuronal injury or disease progression.
Research extends beyond CSF to less invasive specimens: plasma/serum assays (Aβ42, Aβ42/40, P‑tau217/P‑tau181, total tau, NfL), urine biomarkers such as AD7c‑NTP and urinary extracellular vesicle proteomes, and exploratory media including saliva and exosomes. Meta-analyses and cohort studies report variable diagnostic performance (for example, higher concordance of CSF Aβ42/40 with amyloid PET than Aβ42 alone, and reported sensitivities/specificities for some blood and urine markers), indicating promising but heterogeneous results.
Limitations include substantial between-laboratory assay variability, lack of standardized techniques and uniform cutoff thresholds, and incomplete evidence that biomarker testing improves clinical outcomes—particularly given the current paucity of widely available disease‑modifying treatments. Guidelines therefore do not recommend routine biomarker testing for general clinical use and emphasize that biomarkers are currently of limited clinical utility outside specific research or select clinical scenarios.
| Label | Value |
|---|---|
| CSF Aβ42/40 vs Aβ42 concordance with amyloid PET | Aβ42/40 ratio showed higher concordance with PET (89.4%) than Aβ42 alone (74.9%); AUC 0.936 vs 0.814 |
| Urinary AD7c-NTP meta-analysis diagnostic performance | Sensitivity 0.87; Specificity 0.89; Positive LR 8.13; Negative LR 0.15 |
| Plasma biomarkers diagnostic performance (meta-analyses) | Various meta-analyses report plasma Aβ42, Aβ42/40, P-tau217, T-tau, NfL show diagnostic accuracy; reported sensitivities/specificities vary across studies |
| USPSTF 2020 statement | Current evidence insufficient to assess benefits/harms of screening for cognitive impairment in older adults |
| IWG in-vivo evidence | Decreased CSF Aβ1-42 with increased T-tau or P-tau; amyloid PET positivity; or autosomal dominant AD mutation |
Revision History
Policy adopted Avalon policy recommendation effective 7/1/2023.
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