FDA clears blood test to aid evaluation for Alzheimer's disease
A newly FDA-cleared blood test for Alzheimer’s, based on the p-tau217 biomarker, is prompting debate over its high cost, modest predictive power, and how much value early risk information provides when treatments remain limited. Commenters weigh potential medical benefits—such as earlier use of anti-amyloid drugs and lifestyle changes—against psychological impacts and the financial and caregiving burdens of dementia. The conversation also touches on the contentious science around amyloid-targeting therapies, the role of regulation in approving diagnostics, and the importance of planning and support for families facing cognitive decline.
Test characteristics and cost
- PrecivityAD2 is a blood test based on the p‑tau217 biomarker.
- In one cited study, high p‑tau217 implied ~38% 5‑year risk of cognitive impairment vs ~12% for low levels.
- Test cost (~$1,400–1,500) is seen as high compared to other $200–300 Alzheimer’s blood tests; many argue it only makes sense for people with established or strong suspicion of disease.
- Some point out APOE4 status and rare genetic tests like PSEN1 (for early-onset cases) as other high-precision but niche tools.
Clinical usefulness and treatments
- Supporters say early detection matters because new anti‑amyloid drugs (e.g., lecanemab, donanemab, Kisunla, Leqembi) can modestly slow progression, especially if started early.
- Skeptics argue the benefits are small (e.g., ~35% slowing over 18 months), sometimes clinically imperceptible, with serious side‑effect risks, especially in APOE4 carriers.
- There is disagreement over the amyloid hypothesis: some view amyloid as a flawed target; others defend it as still plausible but incomplete.
- Non‑drug interventions mentioned: managing cholesterol, blood pressure, diabetes, sleep apnea; multi‑factor lifestyle programs (e.g., FINGERS); exercise, diet; experimental ideas like creatine and B‑vitamins, with mixed confidence.
Personal, ethical, and caregiving issues
- Many stress the value of knowing early to arrange finances, powers of attorney, and care plans, and to reduce chaos later.
- Others fear increased anxiety, over‑interpretation of minor lapses, and “more time to worry and despair.”
- Multiple accounts describe devastating caregiver burdens, high institutional costs, poor care quality, and family conflict; some mention euthanasia as a hoped‑for option.
- Some note that everyone should periodically put affairs in order, regardless of testing.
Regulation, FDA, and insurance
- One view: tests are not harmless; they drive major medical and financial decisions, so FDA oversight is needed to ensure accuracy and prevent “Theranos‑style” fraud.
- Counter‑view: regulatory throughput is too slow and should rely more on physician judgment, with stronger penalties for outright fraud.
- FDA clearance is also seen as a gateway to insurance reimbursement.
Research and trial impact
- Several see the test’s main current value as research infrastructure: cheaper, earlier screening for trial candidates and better longitudinal data.
- Concerns are raised about potential p‑hacking and the need to verify that predictive claims hold in real-world populations.