Two new FDA-cleared blood tests can now help doctors evaluate Alzheimer’s-related biomarkers without a spinal tap or PET scan.
In the span of one week this month, the FDA cleared two new blood tests that help doctors evaluate Alzheimer’s disease — on August 20, C2N Diagnostics’ PrecivityAD2, and on August 24, Roche’s Elecsys pTau217. That brings the total to four FDA-cleared Alzheimer’s blood biomarker tests in a field that had none until May 2025. For Orange County families who have spent years watching a parent’s memory slip without a clear answer, this isn’t a lab-industry footnote. It’s a real, practical shift in how — and how early — a diagnosis can happen, and it changes the conversation to have with a primary care doctor this fall.
What Actually Changed on August 20 and 24
Until May 2025, there was no FDA-cleared blood test for Alzheimer’s disease at all. A conclusive answer required a PET scan (expensive, not always covered, and not offered everywhere) or a spinal tap to sample cerebrospinal fluid (invasive, and understandably something many older adults and their families want to avoid). In just over a year, that has changed twice in one week and four times total. PrecivityAD2 measures the ratio of amyloid proteins (Aβ42 and Aβ40) along with two forms of tau protein in the blood, using high-resolution mass spectrometry, and is cleared for use in adults as young as 40 — the youngest age range of any cleared test so far. Elecsys pTau217 measures a single biomarker, phosphorylated tau 217, and is built to run on Roche’s cobas laboratory platform, which is already installed in more than 4,500 locations across the United States, making it one of the more widely accessible of the four tests on a practical, where-can-I-actually-get-this-done basis.
PrecivityAD2 vs. Elecsys pTau217, Side by Side
| Detail | PrecivityAD2 | Elecsys pTau217 |
|---|---|---|
| Maker | C2N Diagnostics | Roche, developed with Eli Lilly |
| FDA clearance date | August 20, 2026 | August 24, 2026 |
| Cleared for ages | 40 and older | 55 and older |
| What it measures | Amyloid ratio (Aβ42/Aβ40) plus tau217/total-tau217 ratio | Single biomarker: phosphorylated tau 217 (p-tau217) |
| Order in FDA clearance timeline | 3rd cleared blood-based Alzheimer’s test | 4th cleared blood-based Alzheimer’s test |
| Lab platform | Send-out mass spectrometry lab | Roche cobas — 4,500+ US instruments already installed |
| Intended use | Aid in evaluating adults with signs of cognitive impairment | Rule amyloid pathology in or out for symptomatic adults, primary or specialty care |
Both tests share the same core limitation, and it’s the one detail worth remembering above all others: neither is approved as a screening test for someone who feels fine and simply wants reassurance. Both are cleared for adults who are already showing clinical signs of cognitive decline — noticeable memory lapses, confusion, or difficulty with familiar tasks — and both are meant to be interpreted by a clinician alongside a full evaluation, not read on their own like a home pregnancy test.
A blood biomarker test is ordered as part of a clinical evaluation with a doctor — not taken on its own like an at-home screening kit.
Why This Matters More in Orange County Than the Headlines Suggest
A faster, less invasive path to a biomarker result changes three things that matter directly to local families. First, it can shorten the gap between “something feels different” and an actual answer — a gap that today often stretches into months of waiting for a neurology referral and a PET scan slot. Second, an earlier, better-documented diagnosis is often the gatekeeper for programs families in Orange County are already trying to access. The federal GUIDE Model, for example, which offers structured dementia care coordination and a respite benefit, requires a documented dementia diagnosis before a family can enroll — something we’ve covered in detail in our guides to GUIDE Model respite renewal and memory care eligibility rules. A quicker path to that diagnosis is a quicker path to that support. Third, for families managing IHSS, Medi-Cal, or private home care planning, an earlier diagnosis gives everyone — the family, the doctor, and a home care team like ours — more runway to plan a safe, dignified care approach instead of reacting to a crisis.
What a Positive Result Can and Can’t Tell You
- Can: Show a doctor that amyloid or tau biomarkers consistent with Alzheimer’s disease are present, supporting a clinical diagnosis
- Can: Help rule amyloid pathology out when a doctor is trying to distinguish Alzheimer’s from other causes of memory changes
- Can’t: Serve as a stand-alone diagnosis without a doctor’s clinical evaluation
- Can’t: Predict exactly when or how severely symptoms will progress
- Can’t: Be used as a general screening test for someone with no symptoms, under current FDA clearance
What These Tests Cost, and Where Medicare Stands
Coverage is the part families ask about first, and it’s also the part where the rules are narrower than the headlines imply. Medicare Part B has generally paid for Alzheimer’s blood biomarker testing only when a doctor orders it as part of a diagnostic workup for a patient who is already showing symptoms of cognitive decline — not as a preventive or screening test for someone without symptoms, which currently falls outside what Medicare covers. When a test is covered, families should still expect the standard Part B deductible and 20% coinsurance to apply unless a supplemental plan picks up the difference. When a test isn’t covered — because it’s ordered for screening rather than diagnosis, or because a specific Medicare Advantage or commercial plan hasn’t added it to their covered-test list yet — out-of-pocket costs have run anywhere from roughly $50 into the hundreds of dollars depending on the lab and the plan. The honest first step for any Orange County family considering one of these tests is a direct call to the insurance plan before scheduling, not an assumption either way.
Once a diagnosis is documented, families gain access to structured resources — from GUIDE Model respite benefits to home care planning.
What to Do If You’re Considering One of These Tests
Start with the primary care doctor, not a lab website. Bring specific, concrete examples of what’s changed — missed bill payments, repeating the same question, getting lost on a familiar drive — rather than a general sense that “something’s off.” A doctor experienced in evaluating cognitive impairment can determine whether a blood biomarker test is appropriate, order it, and interpret the result alongside a full cognitive assessment. If the doctor isn’t familiar with either test yet, that’s not unusual this soon after clearance; ask whether a referral to a memory specialist, geriatrician, or neurologist makes sense. And regardless of what a test shows, a documented diagnosis is worth pursuing on its own merits — it’s the key that unlocks GUIDE Model support, more targeted Medi-Cal and IHSS planning conversations, and a clearer roadmap for the family.
Before You or a Loved One Gets an Alzheimer’s Blood Test: Checklist
Click each item as you work through it.
- Write down specific examples of memory or thinking changes you’ve noticed, with approximate dates
- Schedule an appointment with the primary care doctor and describe the changes directly, not vaguely
- Ask whether PrecivityAD2 or Elecsys pTau217 is available through the doctor’s affiliated lab or health system
- Call your Medicare plan or insurer to ask directly whether the specific test is covered for diagnostic use
- Ask what the out-of-pocket cost will be if the test isn’t fully covered
- Confirm who will explain the result — the ordering doctor, not just a lab portal notification
- Ask whether a referral to a neurologist, geriatrician, or memory specialist is appropriate either way
- If a diagnosis is confirmed, ask the doctor about GUIDE Model dementia care coordination eligibility
- Start a conversation with family about care planning, regardless of the result
- Keep a copy of the test result and doctor’s notes for any future benefits or program applications
Test What You Know
1. As of the Elecsys pTau217 clearance on August 24, 2026, how many blood-based Alzheimer’s tests has the FDA cleared in total?
2. What is the minimum age Roche’s Elecsys pTau217 test is cleared for?
3. What do these blood tests actually measure?
4. Are PrecivityAD2 and Elecsys pTau217 approved as general screening tests for people with no symptoms?
5. Why does a documented Alzheimer’s diagnosis matter for Orange County families beyond the test result itself?
Frequently Asked Questions
The One Thing to Take From This
Two blood tests being cleared four days apart isn’t a coincidence of timing so much as a sign of how fast this field is moving — four FDA-cleared options now exist where there were none a little over a year ago. For an Orange County family who has been putting off a hard conversation about a parent’s memory, that’s a real, practical reason to stop waiting. The path to an answer is shorter and less invasive than it used to be, and a documented diagnosis opens doors to real support, not just more uncertainty.
Navigating a New Diagnosis?
At Home VA Staffing helps Orange County families build safe, dignified dementia and memory care plans at home — whether you’re just starting to ask questions or already have a diagnosis in hand.
This article is provided for general informational purposes and reflects publicly available information from the FDA, Alzheimer’s Association (alz.org), and manufacturer announcements regarding PrecivityAD2 and Elecsys pTau217, current as of August 28, 2026. It is not medical, diagnostic, or insurance advice. Test availability, clinical guidance, and coverage policies can change; confirm current details with a physician and your insurance plan before making testing or care decisions. At Home VA Staffing is a home care staffing agency, not a medical or diagnostic provider.
