The $499 Alzheimer’s blood test — and the other half of the story

This month, mailboxes across Vero Beach started receiving offers for a $499 “Alzheimer’s” blood test — a p-tau217 biomarker test, age 55 and up, no referral needed, results by mail in about two weeks. A $75-off promotion followed two weeks later. These tests will show up in your inboxes and social media feeds. Expect more of this, not less: these tests were everywhere at this summer’s international Alzheimer’s conference in London, and given the demographics of the Treasure Coast, this market is arriving here first.

The other half of the same market is the self-administered digital “brain test” — an app-based cognitive test a person takes alone, at home or on a tablet in a waiting room. One product measures biology. The other measures thinking. Neither provides an answer on its own.

Start with the blood test. P-tau217 is a real scientific advance — but the result arrives with no cognitive baseline and no one to interpret it. In a person with no symptoms, amyloid pathology is common enough that a positive result on its own says very little about whether that person will ever develop symptoms. Reduced kidney function can elevate the marker independent of anything happening in the brain. And a result in your record can raise long-term-care insurance underwriting questions most people don’t consider until after they’ve tested. The New York Times reported in August on exactly this: people with normal cognition and an elevated result, left with confusion and distress — information without a plan.

Now the brain tests. A review I co-authored, published in Alzheimer’s & Dementia in August, examined every self-administered digital cognitive test with published validation evidence. Of 79 tools identified, only four had enough real-world evidence to evaluate at all, and none fully met the standard for use as a cognitive evaluation. Several correctly identified only a quarter to under half of people who actually had mild cognitive impairment — a “normal” result is weaker than it sounds. And almost none were checked against biology: not one study in the review used a blood biomarker to connect the score to what is happening in the brain.

Notice what is missing from both products: what happens after the result arrives. An abnormal result becomes proof that decline has started and is coming fast. A normal one becomes permission to stop paying attention. Both conclusions are wrong — and the first one changes how a person lives while they wait for something that may not be happening.

Here is the context that is left out. Mild cognitive impairment describes how someone is functioning now. It is not a forecast, and it is not a synonym for early Alzheimer’s or Parkinson’s or any other cognitive or neurodegenerative disorder — roughly half of the people who meet criteria for it don’t have Alzheimer’s biology behind it at all. Sleep, medications, thyroid, depression, and hearing loss can all produce similar pictures, and some of that is treatable. Depending on the underlying pathology and disease(s), it can move far more quickly or slowly than the version people picture.

The two halves only become useful together. A biomarker without a cognitive baseline is a number without context. A cognitive screen without biology is a snapshot without a cause. What turns either into something a family can act on is the pairing — interpreted by someone who knows the person. That is the work: sit down with a family, put the result in the context of how the person is actually functioning, and turn a number into a plan.

If one of these mailings has reached your house or your inbox or social media, or you are holding a result you don’t know what to do with, call me directly: (772) 202-0486. I have also written two short plain-language guides — one on the blood test, one on the digital brain tests. Email luke@treasurecoastcognition.com and I will send you both.