A team of researchers at New York University (NYU) says a blood test can detect the earliest biological signs of Alzheimer’s disease up to 10 years before the condition’s most noticeable symptoms appear.
The findings come from work led by Professor Allal Boutajangout, a Moroccan neurologist and neuroscientist, and Professor Thomas Wisniewski at the NYU Grossman School of Medicine. The researchers say the test could help identify people at risk earlier, allowing doctors to begin treatment before dementia develops.
In an interview with Morocco’s state news agency MAP, Professor Boutajangout said the approach analyses several biomarkers in blood plasma that are linked to Alzheimer’s disease.
The test measures amyloid beta protein ratios (Aβ42/Aβ40), phosphorylated tau proteins (p-tau181 and p-tau217), neurofilament light chain (NfL), which indicates nerve cell damage, and glial fibrillary acidic protein (GFAP), a marker of brain inflammation.
The researchers compared blood samples from three groups: people with no cognitive impairment, people with subjective cognitive decline whose memory complaints could not be detected through clinical examinations, and patients with mild cognitive impairment.
The results showed more than 90% agreement with amyloid PET brain scans and cerebrospinal fluid tests obtained through lumbar punctures. The blood tests also distinguished different stages of Alzheimer’s disease with high accuracy.
According to Professor Boutajangout, the biomarkers can reveal the disease’s earliest biological changes eight to 10 years before memory loss or other clinical symptoms become apparent. “These biomarkers offer the capability to highlight the initial mechanisms of the disease eight to ten years before the emergence of primary clinical signs.”
During that period, he said, brain damage develops gradually but often remains undetected using conventional diagnostic methods.
Professor Boutajangout said the findings represent “a major step toward targeted preventive medicine”, allowing doctors to intervene before clinically apparent dementia develops and helping speed up care for vulnerable patients.
He added that incorporating the blood test into screening programmes could make it easier to identify people at risk, ensure approved treatments are given at the most effective stage of the disease, rule out reversible causes of cognitive decline, and improve long-term patient monitoring.
The research is being carried out at the NYU Grossman School of Medicine’s Center for Cognitive Neurology and Biomarkers Core Platform, where Professor Boutajangout serves as Associate Professor of Neurology and Neuroscience. Professor Wisniewski directs the Pearl I. Barlow Center for Memory Evaluation and Treatment.
The team is also studying blood biomarkers for other neurological disorders, including Parkinson’s disease, frontotemporal dementia, traumatic brain injury, stroke, autism and amyotrophic lateral sclerosis (ALS).
Professor Boutajangout said blood testing offers a simpler, cheaper and more accessible alternative to PET scans and lumbar punctures. While PET scans typically cost between $3,000 and $5,000, blood-based tests generally range from $400 to $1,200.
Researchers say blood tests could be used as a first-line screening tool in primary care, with more complex procedures reserved for cases requiring confirmation.
Earlier detection could also support access to disease-modifying Alzheimer’s treatments such as Leqembi (lecanemab), developed by Eisai and Biogen, and Kisunla (donanemab) from Eli Lilly. Both drugs target amyloid plaques in patients with early-stage Alzheimer’s disease and require confirmation of brain amyloid pathology before treatment begins.
The market for blood-based Alzheimer’s diagnostics is expanding as healthcare systems increasingly adopt early screening. The global market is estimated to have grown from $169.2m in 2025 to $194.8m in 2026 and is projected to reach $529.9m by 2033, representing a compound annual growth rate of 17.4%. North America accounts for more than 43% of global revenue, reflecting its established clinical networks and widespread use of screening programmes.
