FDA clears first Alzheimer's blood test for patients as young as 40

The U.S. Food and Drug Administration has cleared C2N Diagnostics' PrecivityAD2 blood test for use in patients aged 40 and older who are experiencing potential cognitive symptoms of Alzheimer's disease. It is the first FDA-cleared blood test for Alzheimer's available to people in this age group.

The test uses mass spectrometry to measure plasma ratios of Aβ42/40 and p-tau217/np-tau217, producing a score that classifies results as negative, likely positive, or positive for Alzheimer's pathology. In a clinical validation study of 1,142 symptomatic adults, the test accurately identified 97.6% of positive biomarkers, with consistent results even in patients with comorbidities such as chronic kidney disease and diabetes.

The technology was developed by researchers at Washington University School of Medicine in St. Louis, co-led by Randall J. Bateman, MD, and David M. Holtzman, MD. C2N Diagnostics, a WashU startup, acquired exclusive commercial license rights and further developed and validated the assay.

Previously, detecting brain amyloid plaques required either PET imaging or a lumbar puncture to obtain cerebrospinal fluid. The blood test is intended for patients already showing cognitive decline, not for general population screening.

According to the Alzheimer's Association, approximately 7.4 million Americans aged 65 and older are living with Alzheimer's disease, and an estimated 200,000 more have younger-onset disease. Earlier detection can allow patients to access treatments when they are most effective.

Isobel Coleman, CEO of the Alzheimer's Drug Discovery Foundation, noted that just over a year ago there were no FDA-cleared blood tests for Alzheimer's, and now there are three. She said the clearance demonstrates how sustained early investment in translational science moves promising ideas from the lab to patients.