The FDA cleared C2N Diagnostics' PrecivityAD2 blood test Thursday for adults 40 and older showing signs of cognitive impairment, the youngest clearance any Alzheimer's blood test has received. [1] It is also the third blood-based biomarker test cleared in just over a year. Isobel Coleman, chief executive of the Alzheimer's Drug Discovery Foundation, noted that count stood at zero twelve months ago. [1]

The science is the easy part. Alzheimer's pathology can begin 15 to 20 years before symptoms appear, which is why the age-40 floor matters and why the ADDF, which seeded C2N in 2008 and pushed $7 million more through its Diagnostics Accelerator, framed the decision as precision medicine arriving early. [1]

The money is not easy. The announcement release runs long on amyloid probability algorithms and names no price and no payer. [1] Clearance tells clinicians the test works. It does not tell a 46-year-old with a worried spouse whether an insurer reimburses the draw, or what a positive result obliges anyone to do next. Alston & Bird's weekly regulatory roundup logged the clearance among the week's Federal Register notices, precisely where payment questions get lost. [2]

Those questions start now, in primary-care offices the blood test is supposed to reach. The gap between cleared and covered is where access actually gets decided, and the parties who decide it have not spoken yet.

-- NORA WHITFIELD, Chicago