Blood Tests at Last

If you want to receive one of the monoclonal antibody treatments for Alzheimer’s disease, you need a formal diagnosis. A formal diagnosis will certainly begin with neurological tests of your memory and cognition as well as interviews with friends and family that know you. But it should also include biomarker evidence. Currently, the gold standard biomarkers are tests of your cerebrospinal fluid via a spinal tap and a PET scan of your brain. The spinal tap is a bit uncomfortable, and the PET scan is expensive.  

But something else is now here, and it’s much simpler, cheaper, and less invasive.  

Consistent with what we’ve said in the past, it’s one of the new blood tests. These tests are very sensitive and comparatively inexpensive. Some researchers claim they identify Alzheimer’s many years before the first symptoms, and, even without insurance, they may cost only a few hundred dollars.  

But until now, insurance wouldn’t cover them, and they couldn’t be used to justify a prescription for the two prominent monoclonal antibody treatments, Leqembi and Kisunla. Why not? Because, up to now, blood tests have not been approved by the FDA for diagnosing Alzheimer’s.  

But that was then, this is now. As of May 16, 2025, the FDA has approved a blood test for Alzheimer’s diagnosis. It is the The Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio (Lumipulse G) test. The test measures the ratio of specific species of tau protein and beta amyloid in the blood that would be anticipated in someone with Alzheimer’s. Lumipulse G was developed by the Japanese medical research and development company, Fujirebio Diagnostics, Inc. (The word “Lumipulse” is a registered trademark of Fujirebio.) Here’s the FDA’s press release on the topic.  

Readers of this blog know that we’ve been following development of these tests since 2018, and this test isn’t the only one out there. It’s just the first to gain FDA approval. So expect more in the future.  

Readers will also know that I believe these tests will be a blow to the long-term care insurance industry if they’re allowed to be a qualification factor for enrollment in one the insurance programs. If, on the one hand, the insurance company knows that you’re already developing Alzheimer’s, will they insure you? If so, at what price? If you learn that you don’t have Alzheimer’s and are unlikely to develop it in the future, will you still be interested in insurance? If so, how much would you be willing to pay? If some people know that they are developing Alzheimer’s, but this is hidden from the insurance companies, won’t they flood the insurance companies with demands for enrollment? And won’t those who learn they don’t have it decide not to enroll in much larger numbers? This will surly skew the actuarial numbers the insurance companies apply in setting their rates.

So, who knows? If nothing else, the tests will help people better understand how to navigate their personal situations.  

Thanks to my friend Mike in Virginia (a high school classmate) for prompting me to write on this topic.