Blood test to diagnose Alzheimer's gets approval in US

The US approved the first blood test for Alzheimer's on Friday, potentially allowing patients to begin treatment sooner using newly approved medications that slow the spread of the terrible neurological illness.

Fujirebio Diagnostics created the test to assess the ratio of two proteins in the blood. The rato is associated with amyloid plaques in the brain, a hallmark of Alzheimer's that has thus far been diagnosed exclusively by brain imaging and spinal fluid research.

"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."

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While they do not cure Alzheimer's, lecanemab and donanemab, two FDA-approved therapies that target amyloid plaque, have been demonstrated to somewhat moderate cognitive deterioration.

Advocates of intravenous antibody treatments, including many neurologists, claim they can provide patients a few more months of independence and are more likely to be beneficial if begun earlier in the disease's course.

In clinical trials, the blood test showed results that were mostly consistent with positron emission tomography (PET) brain scans and spinal fluid analyses.

"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.