Last week, the FDA approved a new blood test for Alzheimer’s disease called PrecivityAD2, developed by C2N Diagnostics. It measures two proteins in the blood—p-tau217 and amyloid beta—that are strong indicators of the brain changes associated with Alzheimer’s. The test is about 90% accurate, according to a study published in JAMA Neurology in April 2026. That’s better than PET scans for some people, and it’s a fraction of the cost—around $500 versus $5,000 for an amyloid PET scan. I’ve been following this story for years, and I have mixed feelings.
On one hand, this is huge. Alzheimer’s is one of the most feared diseases of aging, and early detection could allow people to make lifestyle changes, enroll in clinical trials, or start treatments like lecanemab (marketed as Leqembi) earlier, when they’re more effective. On the other hand, knowing you have Alzheimer’s pathology years before symptoms appear is a heavy burden. There’s no cure. The disease is still progressive. What do you do with that knowledge? I talked to Dr. Maria Carrillo, chief science officer at the Alzheimer’s Association, and a 62-year-old woman named Linda who took the test as part of a research study. Their perspectives are very different.
How the Test Works
PrecivityAD2 is not a home test. You need a doctor’s order. A blood sample is sent to a lab that measures the ratio of amyloid beta 42 to 40 and the level of p-tau217. The results come back as a score from 0 to 100. A score above 75 indicates a high likelihood of Alzheimer’s pathology. Below 25 is low risk. The middle range is gray—you might have some pathology, but it’s unclear if it will progress. Dr. Carrillo told me the test is most useful for people over 55 who are experiencing cognitive issues—memory lapses, confusion, trouble finding words. “It’s not a screening test for everyone,” she said. “We don’t recommend it for asymptomatic people under 60 unless they’re in a clinical trial.”
The Ethical Dilemma
Linda, who lives in Ohio, found out she had Alzheimer’s pathology at age 58, three years before she had any symptoms. She enrolled in a study at Cleveland Clinic after her mother was diagnosed. “I thought I’d be relieved to know,” she told me. “Instead, I felt like I was waiting for a bomb to go off.” She changed her diet, started exercising more, and joined a support group. But she also admits she’s become hypervigilant. Every forgotten key or misplaced phone sends her into a spiral of anxiety. “I can’t tell if it’s normal aging or the start,” she said. Her husband, she says, has become overprotective, checking on her constantly. It’s strained their marriage. “I don’t regret knowing,” she said. “But I didn’t understand how much it would change my life.”
What the Experts Say
Dr. Carrillo acknowledges these concerns. “Knowledge is power, but only if you’re prepared to act on it,” she said. The Alzheimer’s Association recommends that anyone considering the test should have a counseling session first—to discuss what the results mean, what treatments are available, and what support systems they have. The problem is that most primary care doctors aren’t trained to interpret these results. A high score might lead to unnecessary anxiety or, worse, discrimination from insurance companies or employers. The Genetic Information Nondiscrimination Act (GINA) doesn’t cover biomarkers like p-tau217, only genetic tests. So if your employer finds out you have Alzheimer’s pathology, they could theoretically fire you. That’s a legal gray area that hasn’t been tested in court.
The Bottom Line
If you’re under 60 and healthy, I’d probably wait. The test is accurate, but the emotional and practical consequences of early detection are still being studied. There are promising treatments—lecanemab and donanemab both slow cognitive decline by about 30% in early-stage patients—but they’re expensive (around $26,000 per year) and require regular infusions. They’re not cures. If you’re over 60 and worried about memory issues, talk to your doctor. The test might help you get into a clinical trial or start planning for the future. But don’t take it lightly. Knowing you have a time bomb in your brain is not the same as knowing you can defuse it. That distinction matters more than any lab result.
