WASHINGTON, May 17, 2025 (BSS/AFP) - The United States on Friday approved the first blood test for Alzheimer's, a move that could help patients begin treatment earlier with newly approved drugs that slow the progression of the devastating neurological disease.

The test, developed by Fujirebio Diagnostics, measures the ratio of two proteins in the blood. The rato is correlated with amyloid plaques in the brain -- a hallmark of Alzheimer's that, until now, has been detected only through brain scans or spinal fluid analysis.

"Alzheimer's disease impacts too many people -- more than breast cancer and prostate cancer combined," said Food and Drug Administration Commissioner Marty Makary.

"Knowing that 10 percent of people aged 65 and older have Alzheimer's, and that by 2050 that number is expected to double, I am hopeful that new medical products such as this one will help patients."

There are currently two FDA approved treatments for Alzheimer's: lecanemab and donanemab, which target amyloid plaque and have been shown to modestly slow cognitive decline, though they do not cure the disease.

Advocates for the intravenous antibody therapies, including many neurologists, say they can offer patients a few additional months of independence -- and are likely to be more effective if started earlier in the disease's course.

In clinical studies, the blood test produced results largely in line with positron emission tomography (PET) brain scans and spinal fluid analysis.

"Today's clearance is an important step for Alzheimer's diagnosis, making it easier and potentially more accessible for US patients earlier in the disease," said Michelle Tarver of the FDA's Center for Devices and Radiological Health.

The test is authorized for use in clinical settings for patients showing signs of cognitive decline, and results must be interpreted alongside other clinical information.

Alzheimer's is the most common form of dementia. It worsens over time, gradually robbing people of their memories and independence.