The blood tests and brain scans that may be speeding up Alzheimer's detection

Embargoed until: Publicly released: 2026-05-29 08:30

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A blood test and a brain imaging scan may be two new methods to detect Alzheimer's disease early, according to two separate papers by international authors. The first study of 682 patients in the US and Canada tested a new type of brain scan to detect the build-up of tangled proteins in the brain that are associated with the start of Alzheimer's disease. The test was able to identify twice as many cases of tangled protein build-up than the current standard test. Early and accurate detection of these protein build-ups can help identify people who may benefit from treatment. The second paper used a blood test to detect signals of proteins in the blood of 1,350 dementia free adults in the US that are associated with Alzheimer's disease, and then monitored their mental performance over time. They found that the test could detect proteins associated with Alzheimer's in the blood of people without dementia, and that those people had worse mental performance and accelerated decline in mental performance compared to people who did not have those proteins.

News release

From: The Lancet

The Lancet:New brain scan detects Alzheimer’s Disease biomarkers earlier than current standard, study suggests

A new brain imaging test can detect tau protein tangles - a key biomarker of Alzheimer's Disease (AD) - before symptoms appear and earlier than the method currently used in clinical practice in the United States and Europe, suggests a study published in The Lancet.

AD is defined as a disease that begins with the accumulation of amyloid-beta (Aβ) protein plaques and phosphorylated tau protein tangles in the brain. Early and accurate detection of tau can identify people who are likely to benefit from an anti-amyloid treatment, or to avoid costly and burdensome procedures for people who are unlikely to develop behavioral symptoms of AD.

This study of 682 participants in the USA and Canada with varying ages compared tau PET brain scans, one using the standard tau tracer Flortaucipir and the other with MK6240, a newer tracer primarily used in clinical trial settings. In cognitively unimpaired, amyloid-β-positive participants aged 50-89 years old, MK6240 identified more than twice as many tau-positive cases as Flortaucipir in early tau regions: 54/362 cases for MK6240 (15%) vs 23/362 cases for Flortaucipir (6%). Among cognitively impaired participants, MK6240 also identified more tau involvement (80/282, 28%) than Flortaucipir (46/282, 16%) in late tau regions.

The authors conclude that tau-PET positivity may currently be underestimated, and that the use of more sensitive tau-PET biomarkers can improve detection of early tau pathology and better identify patients most likely to develop AD symptoms.

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The Lancet:Blood test can identify signs of Alzheimer’s Disease decades before symptoms, study suggests

Blood test can identify signs of the accumulation of Alzheimer Disease (AD)-associated proteins (biomarkers) in the brains of dementia-free middle-aged adults, suggests a study published The Lancet. The study also finds higher levels of the biomarkers are associated with worse cognitive performance and an accelerated decline in the adults.

AD is defined as a disease that begins with the accumulation of amyloid-beta (Aβ) protein plaques and phosphorylated tau protein tangles in the brain. Recently, measuring the levels of Aβ and tau proteins in blood has become a way to track changes in these proteins, and can be used as a diagnostic tool for AD. Research on these blood tests and biomarkers have mostly focused on older, white adults; little is known about whether AD-associated protein accumulation relates to cognition in midlife and in more diverse communities.

This study measured the levels of the biomarkers Aβ42, Aβ40, and p-tau217 in the blood of 1,350 dementia free adults in the US with an average age of 61 years. Standard high cut-off levels of Aβ and tau associated with AD were identified in 6% (86/1350) of the study participants. High levels of the biomarkers were associated with worse midlife cognitive performance on cognitive processing speed and executive function (brain function which enables planning, focusing attention, and adapting to new challenges) and higher rates of accelerated decline on verbal memory and processing speed tests taken five years apart.

Authors say the study findings demonstrate the potential of detecting early-stage AD among middle-aged adults using blood tests. Early identification of AD would provide an opportunity for the reduction of modifiable risk factors such as physical inactivity, smoking, poor sleep and untreated hearing loss, as well the provision of medication, potentially delaying the start of cognitive decline and development of AD symptoms.

In a Linked Comment, two experts who were not part of the study say that in younger populations with no cognitive impairments the AD-associated protein blood tests can lead to a higher rate of false positive results, therefore additional diagnostic criteria should always be used alongside the blood tests. The Linked Comment authors caution that ‘these blood biomarkers are not suitable for large scale, untargeted screening for Alzheimer’s disease pathology in cognitively unimpaired populations or in the community.’

Journal/
conference: The Lancet

Research: Link to Paper 1 | Paper 2

Organisation/s: University of Pittsburgh, USA, University of California San Francisco, USA

Funder: TAP serves on a data safety monitoring board for National Institutes of Health (NIH) award 5 R01 AG084834 based at the University of Cincinnati. He also has served on a scientific advisory board at Johnson & Johnson. TAP, BB, and GP have received support to attend meetings from the Alzheimer’s Association. PR-N serves as an advisory board member for Novo Nordisk, Eisai, and Eli Lilly. JF reports receiving personal fees for service on the advisory boards, adjudication committees, or speaker honoraria from AC Immune, Adamed, Alzheon, Biogen, Eisai, Esteve, Fujirebio, Ionis, Laboratorios Carnot, Life Molecular Imaging, Lilly, Novo Nordisk, Perha, Roche, and Zambón, outside the submitted work. He reports holding a patent for markers of synaptopathy in neurodegenerative disease (licensed to ADx, EPI8382175.0). DNS-M received a travel award from the Society of Nuclear Medicine and Molecular Imaging and an honorarium for grant review from the Alzheimer’s Drug Discovery Foundation. He serves on a research council for the Alzheimer’s Association and on a data monitoring committee for Eli Lilly. HO serves on a data safety monitoring board for NIH award 5 R01 AG068062 based at Massachusetts General Hospital. WJJ received a consulting fee from Eisai and participated on data safety monitoring committee for Eli Lilly. DLT participated on a data safety monitoring board for the DSMS REMBRANDT study. GP, BB, and TAP had full access to and verified the underlying data reported in the manuscript, and final responsibility for methodological decisions and submission for publication. The Coronary Artery Risk Development in Young Adults Study (CARDIA) is supported by contracts 75N92023D00002, 75N92023D00003, 75N92023D00004, 75N92023D00005, and 75N92023D00006 from the National Heart, Lung, and Blood Institute. The CARDIA Cognitive Function ancillary study is supported by the National Institute on Aging (NIA) R01AG063887 and R01AG091431. This work was supported by the Alzheimer’s Association Research Fellowship AARFD-23–1150636 and NIA R35AG071916, R01AG063887, R01AG091431, and K99AG083211.

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