A lumbar puncture is not something anyone signs up for lightly - a needle in the spine to confirm a diagnosis families are already dreading. For years, that's what an Alzheimer's diagnosis in Ireland has often meant. New Irish research suggests a simple blood test could do much of that job instead, and it's already moving from the lab towards the clinic.
The diagnosis gap this is trying to close
The scale of the problem is bigger than most people realise. Over 60,000 people live with dementia in Ireland, with Alzheimer's disease accounting for about 70% of cases, according to Trinity College Dublin research published in February 2025. Up to half of people living with Alzheimer's in Ireland remain without a formal diagnosis, the same research found.
That study, run by researchers at Trinity College, the Tallaght Institute of Memory and Cognition and St James's Hospital, examined the blood test plasma p-tau217 in 148 patients attending Tallaght University Hospital who donated both blood and cerebrospinal fluid samples. It was one of the first studies in Europe to assess the test's 'real-world' performance in patients with mild symptoms attending a specialist memory service, and was published in the journal Alzheimer's & Dementia: Diagnosis, Assessment and Disease Monitoring.
Crucially, the 2025 study found the blood test performed strongly even in this 'real-world' group of patients with only mild memory symptoms - the setting where diagnosis is hardest, and where a reliable blood test could have the biggest impact, since these are exactly the patients who might otherwise wait months for a specialist appointment and a lumbar puncture before receiving an answer.
That said, the team was careful about the test's limits: it performed best as a way to rule Alzheimer's in or out at a broad level, while a smaller group of patients with results in a middle, less certain range still needed a follow-up lumbar puncture or brain scan to confirm the diagnosis. The test, in other words, is a powerful first step, not a complete replacement for existing tools in every case.
A second, bigger finding: predicting who declines faster
The same team has since gone further. In February 2026, the Tallaght University Hospital and Trinity College Dublin group published a follow-up finding from one of the largest studies of its kind: tracking more than 300 people with mild-to-moderate Alzheimer's disease across nine European countries over 18 months. They found that two blood-based biomarkers, p-tau217 and GFAP (a marker of brain inflammation), were strongly linked to faster loss of memory, thinking ability and independence.
Notably, these two biomarkers proved more informative than a wider panel of commonly-measured blood inflammation markers, which did not predict disease progression once Alzheimer's had already been established. Episodes of delirium were also linked to more rapid decline.
Dr Seán O'Dowd, a Consultant Neurologist involved in the research, noted that identifying delirium as a marker of faster decline gives clinicians another practical, low-cost signal to watch for in patients already diagnosed with Alzheimer's, alongside the two blood-based markers - since delirium episodes are often flagged during unrelated hospital admissions and can prompt earlier follow-up with a memory service.
The biomarker measurements were made possible using advanced technology at the Trinity Translational Medicine Institute (TTMI). Standardised laboratory assays for using these markers in Alzheimer's diagnosis are currently under review with the European Medicines Agency for clinical use.
Professor Seán Kennelly, Consultant Geriatrician and Director of the Institute of Memory and Cognition at TUH, said the development is 'genuinely transformative' for patients and families, according to an HSE report on the programme published in July 2026. 'Earlier and more accurate diagnosis enables better planning, better access to supports, and more personalised treatment decisions,' Kennelly said, adding that the ability to deliver blood-based biomarker testing nationally could reshape how memory services operate across the country.
From research to routine care
What's striking is how quickly this is moving from paper to practice. Tallaght University Hospital said it anticipates p-tau217 testing becoming available within its specialist memory services later in 2026, which would let doctors integrate the blood test into standard diagnostic pathways sooner rather than waiting years for full rollout.
In June 2026, TUH launched a National Alzheimer's Biomarker Programme, formally starting a validation programme for blood-based biomarker testing. This builds on TUH's existing role as a national referral centre: its National Neurochemistry Laboratory already provides specialist biomarker analysis to 12 hospitals nationwide, processing around 1,000 cerebrospinal fluid samples a year.
Eoin Begley, Chief Medical Scientist in the National Neurochemistry Laboratory at TUH, called it 'a milestone for Alzheimer's diagnostics in Ireland', adding that 'moving from CSF-only testing to validated blood-based biomarkers will enable us to support far more patients, far earlier in their diagnostic journey'. The programme is also linked to the TUH Institute of Memory & Cognition Biobank for Aging & Neurodegeneration, co-led by Dr Antoinette O'Connor, who also co-leads the Dementia Research Network Ireland All-Island Biobank initiative supporting national biomarker research infrastructure.
What families notice on the ground
For families, the practical difference is about time and comfort rather than technology alone. A lumbar puncture typically requires a hospital day-case appointment, a period of lying flat afterwards to avoid headache, and a wait of some weeks for results, whereas a blood draw can be taken during a routine memory clinic visit alongside other tests. Catriona Duffy, Senior Medical Scientist in the National Neurochemistry Laboratory at TUH, is among the team members named by the HSE as running the day-to-day validation work behind the new programme, alongside colleagues including Dr Aoife Fallon, Consultant Geriatrician, and Professor Gerard Boran, Consultant Chemical Pathologist.
The Dublin Gazette reported in June 2026 that the arrival of a new state-of-the-art analyser at TUH, combined with recent European regulatory approvals for blood biomarkers of Alzheimer's, was what allowed the formal validation programme to begin, marking what the hospital called 'a significant milestone in Ireland's preparedness for emerging Alzheimer's therapies and precision-medicine approaches'. That preparedness matters: a number of new Alzheimer's drugs designed to slow the disease, rather than just treat its symptoms, have been approved internationally in recent years, and doctors typically need a confirmed biomarker diagnosis before prescribing them.
The scale of the problem the test is aimed at
Zoom out, and the need for faster, easier diagnosis only gets more urgent. Roche, whose analysers already run in over 50 Irish hospitals with around 86 systems in place, estimates that 64,000 people in Ireland currently have dementia, a figure it projects could more than double over the next 25 years, reaching over 150,000 by 2045. In May 2026, Roche's Elecsys pTau217 test, developed with Eli Lilly, received a CE mark as the first Alzheimer's blood test intended to both rule in and rule out amyloid pathology across primary and specialist care, offering an alternative diagnostic pathway that runs on equipment many Irish hospitals already have installed.
That combination - growing patient numbers and a technology base already present in Irish hospitals - is part of why the Tallaght-led validation work is being watched closely nationally rather than treated as a single-hospital pilot. If p-tau217 testing proves reliable enough for routine use, the infrastructure to run it at scale in other hospitals may already be closer to ready than a brand-new diagnostic technology would normally be.
The Alzheimer Society of Ireland has separately highlighted that faster, less invasive diagnosis matters most in primary care, where GPs are often the first point of contact for a worried family but have historically had limited tools beyond memory questionnaires and a referral letter. A validated blood test that a GP could eventually order, rather than one confined to hospital memory clinics, would shorten the path for many patients well before they ever reach a specialist waiting list.
The Bottom Line
In the space of a year, Irish researchers at Trinity College Dublin and Tallaght University Hospital have gone from proof-of-concept blood testing to a large European study identifying which patients are likely to decline faster, and are now standing up a national validation programme. With EMA review of the assays under way and TUH aiming to offer p-tau217 testing in its memory clinics before the end of the year, thousands of Irish patients could soon be spared the wait, and the needle, that a lumbar puncture requires.
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