WASHINGTON (AP) — A blood test may predict if apparently healthy older adults are likely to develop Alzheimer’s symptoms in the next five or 10 years, researchers reported Wednesday.
That information could be reassuring or terrifying, but for now it's a potential tool to speed drug development by helping to identify and enroll high-risk people into studies of possible Alzheimer's treatments or preventive strategies.
Already large clinical trials are testing if certain drugs could prevent or at least delay the disease — and if any of those pan out, doctors will need an easy way to tell who should try them.
The scientists behind the new study stress that it’s too soon for healthy people to seek out the so-called p-tau217 test, which is currently used to help diagnose whether people experiencing cognitive problems have Alzheimer’s or another disorder.
“Wait and get tested when you can potentially do something about it,” stressed Dr. Reisa Sperling of the Mass General Brigham Neuroscience Institute, the study’s senior author. “At this point it wouldn’t change what I would tell someone to do. I’d still tell them to eat well, sleep well, exercise a lot and stay engaged.”
The new findings showed that symptom-free older adults who harbored very high levels of p-tau217 had a 38% risk of developing cognitive impairment over five years. That risk grew to 78% by 10 years.
The research was published in JAMA and presented at the Alzheimer’s Association International Conference in London.
It’s not clear exactly what causes Alzheimer’s, but its telltale markers are brain-clogging amyloid plaques and neuron-killing tau tangles. The p-tau217 test measures a form of tau that correlates with how much plaque buildup someone has and gives a hint about tangles, Sperling said.
The Mass General Brigham team analyzed data from 2,684 older adults who were healthy when they’d joined some long-running Alzheimer’s studies, receiving the p-tau217 blood test at enrollment and yearly cognitive checkups. Between the earliest enrollment in 2004 and last year, about 478 had developed cognitive impairment.
Study participants with very low p-tau217 levels likewise had a low risk of developing cognitive impairment over the five- to 10-year period.
There’s a conundrum in predicting Alzheimer’s: Lots of people harbor high levels of amyloid plaques yet never get dementia. A leading theory is that at some point amyloid buildup triggers an abnormal type of tau to form tangles, leading to symptoms.
Sperling said the blood test data offers some new clues. While different intermediate levels of p-tau217 signaled progressive risk, only the very highest level seemed to correlate with other evidence about that tipping point.
“This is a gradual process where amyloid and tau build up in the brain and this blood-based biomarker is telling you how far you are in that process,” she said.
Scientists not involved in the study praised it but also offered some reasons to be cautious. One is that only a small fraction of study participants had been tracked for a full decade, so there's less confidence in the 10-year risk estimate than the five-year risk estimate.
Also, the predictions could be clouded by other factors — older people may be at risk of dying from something else, or have heart-related problems that can cause vascular dementia rather than Alzheimer’s, noted Drs. Suzanne Schindler of Washington University in St. Louis and David Wolk of the University of Pennsylvania in a commentary published in JAMA.
The blood tests “are not yet precise enough to guide individualized prognosis,” wrote Schindler, who also studies p-tau217’s prognostic potential, and Wolk. Still, they said the new work has “provided a crucial piece of the puzzle.”
Already “we have people coming saying, ‘I want this blood test. I have a family history of Alzheimer’s disease,’” said Jessica Langbaum of the Banner Alzheimer’s Institute in Phoenix, something she strongly discourages — for now.
“These findings are quite strong,” Langbaum added, and a predictive blood test would be “really important” — but only if ongoing studies eventually find a drug that could help people before symptoms begin.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.
FILE - A human brain affected by Alzheimer's disease is displayed at the Museum of Neuroanatomy at the University at Buffalo in Buffalo, N.Y., on Oct. 7, 2003. (AP Photo/David Duprey, File)
MONTREAL (AP) — Canadian Prime Minister Mark Carney said Friday he expects to conclude negotiations with the European Union in June to make Canada the bloc’s first “associate member,” as both sides forge an unprecedented alliance to protect their sovereignty in a changing world order.
U.S. President Donald Trump’s trade war and threats against traditional allies have accelerated efforts by Canada and Europe to reduce their dependence on Washington and strengthen their economic and security ties.
“What brings us together goes far beyond geography. We see the world through the same eyes,” European Commission President Ursula von der Leyen said. “These headwinds won’t stop blowing. This change is permanent.”
Carney said the alliance would help Canada and Europe withstand economic pressure and make their own decisions rather than be dictated to by more powerful countries.
Trump has suggested Canada’s proposed EU arrangement could be a “hostile act” and threatened tariffs on Europe if he considered it unfriendly.
Asked whether Trump could eventually be invited to join the alliance, Carney did not directly answer but insisted it was not aimed against any country.
“It is about reinforcing sovereignty. Why? So we can live our lives as we choose, our people can live their lives as they choose and have the full freedoms that people enjoy in the European Union and in Canada,” Carney said.
“It’s not against anything, it’s for,” he said.
Carney, von der Leyen and European Council President António Costa launched the “Alliance for the Future” at the end of a two-day summit in Montreal, announcing progress on digital trade, European investment in Canadian critical minerals and artificial intelligence.
“Today we move toward associate membership for Canada, and we launch a new alliance for the future,” Carney said.
But the joint declaration made no mention of associate membership, despite both Carney and von der Leyen championing the designation. Instead, the leaders agreed to define an “ever-closer association” by their next summit in 2027.
Carney said Canadian Cabinet ministers and European commissioners would meet in March before he attends European Council meetings in June, where he intends to conclude negotiations on the proposed relationship. Costa confirmed the invitation and said more details would be announced then.
Von der Leyen said Friday there was broad support for bringing Canada closer to the EU, despite disagreement over what to call the relationship.
“On one thing I’m absolutely sure, having spoken about it in the last weeks, is the broad support of having Canada much, much closer to the European Union,” she said.
Canada and the EU already have a free-trade agreement that eliminated most tariffs. They wrapped up negotiations Friday on a new digital trade agreement to make it easier for businesses to sell across the Atlantic.
Canada also signed an agreement allowing the European Investment Bank to finance Canadian critical minerals projects, potentially opening a new source of investment for the country’s mining industry.
Canada will also join a European supercomputing initiative that Carney said could transform research. He said Europe’s JUPITER supercomputer could complete in one day calculations that would take Canada’s most powerful research computer six months.
“A tech startup in Vancouver will have a smoother path to customers in Berlin,” Carney said. “Bottom line: less red tape, more growth, more opportunity.”
The two sides also concluded negotiations on a competition agreement intended to curb anti-competitive practices and lower prices for consumers. They will explore linking their instant-payment systems to make cross-border transfers faster and cheaper.
The broader Alliance for the Future could eventually include other like-minded countries, with Canada and the EU at its core.
Costa said the two sides wanted to create a relationship unlike any previous EU partnership with a country outside the bloc.
“Our relationship is so special that we want to create something new: to go beyond a simple association, everything short of full EU membership,” Costa said.
The leaders also agreed to study the feasibility of exporting Canadian liquefied natural gas to Europe and explore new undersea cables connecting Canada, Europe and Asia.
Canada and the EU will begin negotiations on expanding Canadian participation in Erasmus+, the European student exchange program, and explore ways to make it easier for young people to study and work across the Atlantic.
The two sides also agreed on a new border security arrangement and pledged closer cooperation on defense, cybersecurity, Arctic security and countering foreign interference.
The United States accounted for 71.7% of Canada’s merchandise exports in 2025. Carney wants to double exports to other countries over the next decade.
Prime Minister Mark Carney participates in a trilateral meeting during the EU-Canada summit in Montreal on Friday, Oct. 30, 2026. (Christinne Muschi /The Canadian Press via AP)
Prime Minister Mark Carney, right, gestures as he arrives with European Commission President Ursula von der Leyen and European Council President Antonio Costa for their closing press conference at the EU-Canada summit in Montreal on Friday, Oct. 30, 2026. (Christinne Muschi /The Canadian Press via AP)
Canadian Prime Minister Mark Carney, centre, arrives at the Canada-EU Summit with President of the European Council, Antonio Costa, left, and President of the European Commission, Ursula von der Leyen, in Montreal, Friday, Oct. 30, 2026. (Christopher Katsarov/The Canadian Press via AP)
Canada Minister of Foreign Affairs Anita Anand, right and High Representative of the European Union for Foreign Affairs and Security Policy Kaja Kallas pose after signing the Canada-EU Host Country Agreement in Montreal, Thursday, Oct. 29, 2026. (Christopher Katsarov/The Canadian Press via AP)
Signage for the Canada-EU summit, in Montreal, is seen on Thursday, Oct. 29, 2026. (Christopher Katsarov/The Canadian Press via AP)
Canada Minister of Foreign Affairs Anita Anand, right and High Representative of the European Union for Foreign Affairs and Security Policy Kaja Kallas sign the Canada-EU Host Country Agreement in Montreal, Thursday, Oct. 29, 2026. (Christopher Katsarov/The Canadian Press via AP)
Canada Prime Minister Mark Carney looks on during a roundtable meeting with business leaders during the Canada-EU Summit, in Montreal, Thursday, Oct. 29, 2026. (Christopher Katsarov/The Canadian Press via AP)
President of the European Commission Ursula von der Leyen, right, gives remarks alongside Canada's Prime Minister Mark Carney at a roundtable with business leaders during the Canada-EU Summit in Montreal, Thursday, Oct. 29, 2026. (Christopher Katsarov/The Canadian Press via AP)
