Green Light for First Blood Test to Diagnose Alzheimer’s Disease in the USA
The U.S. Food and Drug Administration (FDA) recently approved the first test to use a blood sample to diagnose Alzheimer’s disease. [1] The earlier Alzheimer’s disease can be diagnosed, the earlier the access to intervention. However, it can be hard to detect the disease in its earliest stages. The imaging test most often used is a positron emission tomography (PET) scan, which shows the presence of amyloid plaques—a hallmark of Alzheimer’s—in the brain. The scan is costly, not universally available and exposes patients to radiation. Another option is to test fluid from a spinal tap or lumbar puncture – an invasive procedure that doctors and patients often try to avoid. Thus, this new blood test could be a changer in the way providers diagnose Alzheimer’s disease. The test, called Lumipulse, is for adults aged 55 and older who are showing indications of Alzheimer’s disease. It is not intended to be a general screening test for asymptomatic people; nor is it designed to diagnose other dementia types, such as vascular, Lewy Body or frontotemporal dementias.
A ratio of brain proteins
The Lumipulse test is a simple blood draw which looks at the ratio of two proteins that build up in the brains of people with Alzheimer’s – beta-amyloid and phosphorylated tau. The detection of these proteins correlates with the presence of amyloid plaques in a person’s brain, which can cause the decline of healthy brain cells, a key sign of Alzheimer’s. During review of the Lumipulse test, the FDA evaluated data on 499 plasma samples from adults aged 52 to 93 years, who were cognitively impaired and who had amyloid pathology confirmed by a PET scan or cerebrospinal fluid (CSF) testing. About 92% of individuals with a positive Lumipulse result were found to have amyloid plaques by PET scans or CSF testing. Meanwhile, about 97% of individuals with a negative Lumipulse result were found to have amyloid plagues by PET scan or CSF testing. Fewer than 20% of patients received an indeterminate Lumipulse result.
People want to know if they have Alzheimer’s disease
The Lumipulse test means that people could get diagnosed with Alzheimer’s disease sooner. This is important because the approved medications for Alzheimer’s disease are geared towards slowing the progression of the condition in its early stages. A blood biomarker could also mean more testing of people in rural or underserved areas, due to it being cheaper and more accessible than other tests. A survey conducted by the Alzheimer’s Association earlier this year indicated that 4 in 5 Americans would want to know if they had Alzheimer’s disease before it interfered with their daily activities; and 9 out of 10 Americans said they would want to take a simple test—such as a blood biomarker test—if it were available. [2]
Potential for well-intentioned misuse
The FDA details that the Lumipulse test risks false positive and false negative results. Indeed, whilst dementia experts applaud the first blood biomarker test, they have raised concerns around the potential for overdiagnosis and misdiagnosis. To minimise misuse, the first iteration of clinical practice guidelines for blood biomarkers was recently presented at the Alzheimer’s Association International Conference. [3] Certainly, accompanied by the right regulations, Lumipulse—and other blood biomarkers to follow—have an incredible possibility for good. We wait to hear how other countries, including Australia, respond to the new development.
[1] https://www.fda.gov/news-events/press-announcements/fda-clears-first-blood-test-used-diagnosing-alzheimers-disease
[2] https://www.alz.org/alzheimers-dementia/facts-figures
[3] https://aaic.alz.org/releases-2025/clinical-practice-guideline-blood-based-biomarkers.asp