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Two studies published in The Lancet look at a blood test and new brain scan for detecting early biomarkers for Alzheimer’s Disease.
Prof Roslyn Bill, 50th Anniversary Professor of Biotechnology, College of Health & Life Sciences, Aston University, said:
(on brain scan) “Alzheimer’s disease remains incurable, and the development of effective new therapies depends upon identifying patients most likely to benefit from therapeutic intervention. Biomarker discovery is therefore an essential and rapidly advancing area of research that enables more accurate patient stratification for both clinical trials and clinical practice. This extensive study evaluated two PET tracers used to detect tau pathology, a hallmark of Alzheimer’s disease. One tracer, Tauvid, is already in clinical use, while the second, [18F]MK6240, remains investigational. Although both tracers detected tau accumulation, [18F]MK6240 identified tau pathology at earlier stages of disease progression. Earlier and more sensitive detection of tau pathology could improve patient selection for clinical trials, support earlier diagnosis, and facilitate more targeted therapeutic intervention. As such, this work represents an important advance for the Alzheimer’s disease field.
(on blood test) “Alzheimer’s disease remains incurable, and its symptoms develop over decades. Earlier identification of individuals at risk could therefore enable interventions aimed at slowing disease progression before significant cognitive decline occurs. In this study, the authors assessed blood-based biomarkers associated with Alzheimer’s disease and demonstrated that these biomarkers are detectable as early as midlife, where they are associated with measurable differences in cognitive performance. The ability to identify individuals with early Alzheimer’s-related pathology using accessible blood tests could facilitate the development of preventive strategies and improve recruitment into clinical trials aimed at delaying or preventing the onset of dementia.”
(on the blood test paper) Prof Paresh Malhotra, Head of the Division of Neurology in the Department of Brain Science, Imperial College London, said:
“The researchers have looked at what happens when testing 1350 people, with an average age of 61, with the new blood tests that pick up the underlying protein changes that occur in Alzheimer’s disease. A relatively small proportion of people without dementia (15% or less, depending on the particular test) tested positive on these blood tests and these individuals tended to do worse on some, but not all, tests of thinking.
“This study has used the new blood tests-that have started to enter clinical practice-in a relatively large number of people below the age where cognitive symptoms become most frequent. This adds to our knowledge about how many people will have abnormal Alzheimer’s blood results at this age, and provides further information about how common these changes are. Because it is at a single time point, it does not tell us how about how the proportions in this group will change over time. It also only tested people who had managed to continue to be part of a study for several decades, and we do not know how this will have affected the proportions.
“It is essential that we continue doing research like this and into the processes that lead to altered brain function in Alzheimer’s and other dementias. It is also critical that we keep in mind that having an abnormal blood test is not in itself a clinical diagnosis and does not mean that someone will inevitably get dementia. At the moment we only really understand what these tests mean when there is evidence of cognitive impairment, so they can be helpful where there has been a clinical assessment but we do not yet fully understand their implications when they have been done without any such assessment or in people where there is no objective evidence of cognitive difficulties.”
(on both papers) Prof Tara Spires-Jones, Professor of Neurodegeneration at the University of Edinburgh, Division Lead in the UK Dementia Research Institute, and Past President of the British Neuroscience Association said:
“In the study by Povala and colleagues, scientists compared two radioactive molecules that label tau pathology in the brain. They observed that in brain scans, the newer experimental compound MK6240 was better than the approved compound flortaucipir at detecting tau pathology. In the blood test study by Jiang and colleagues, data from blood samples from over 1300 people with an average age of 61 years showed that around 5% of cognitively normal people in midlife have signs of Alzheimer’s pathology. People with signs of Alzheimer’s disease in the blood test showed signs of cognitive decline. These are both well conducted studies that advance what we know about detecting the early brain changes associated with Alzheimer’s disease. It is important to note that while these are important scientific findings that will be very useful for research and clinical trials, neither the blood test nor the brain scans investigated are available for routine clinical use in the UK.”
Dr Jacqui Hanley, Head of Research Funding, at Alzheimer’s Research UK said:
“These two studies add to a growing body of evidence showing progress in detecting the biological changes linked to Alzheimer’s disease much earlier in life, using a range of biomarkers from blood tests through to advanced brain imaging.
“Being able to identify these changes sooner than we can now could be incredibly valuable. If we can identify Alzheimer’s disease earlier on, it would open up opportunities for people to take part in studies of new treatments. We could also identify people who might benefit from disease-modifying treatments that are indicated for early-stage disease.
“In the UK, many people wait far too long for a dementia diagnosis, meaning they often miss out on these opportunities. This is why there’s so much excitement around the potential for blood tests, alongside other assessments.
“Accurate blood tests could improve how a diagnosis is made, as they are less invasive, scalable and potentially more accessible than existing tools such as PET brain scans and lumbar punctures.
“Detailed brain imaging remains important for understanding the extent and stage of disease more precisely, which is critical for research and treatment decisions. The study of tau PET scans suggests newer methods might detect Alzheimer’s‑related changes earlier than existing techniques, which could enable earlier identification of disease and more precise selection of participants for clinical trials.
“As exciting as the results of these two observational studies are, we will need further research in larger and diverse groups of people before the approaches could be used routinely. We are still learning how these biomarkers behave over time, especially in people who are otherwise healthy, and we do not understand why some people can have these biomarkers yet not develop dementia.
“The Blood Biomarker Challenge* is looking at blood test use in a real-world setting. Its aim is to revolutionise dementia diagnosis and make blood tests available in the NHS by 2029. At Alzheimer’s Research UK we’re funding research into new accessible ways to improve diagnosis and ultimately get us closer to a cure.”
*The Blood Biomarker Challenge is a multi-million-pound research programme supported by Alzheimer’s Society, Alzheimer’s Research UK, the National Institute for Health and Care Research, Gates Ventures, and players of the People’s Postcode Lottery.
(on the blood test) Dr Richard Oakley, Associate Director of Research and Innovation at Alzheimer’s Society, said:
“Dementia is the UK’s biggest killer and early and accurate diagnoses have never been more important. Blood-based biomarkers offer a promising, cost-effective and less invasive way of detecting Alzheimer’s disease so it’s encouraging to see momentum in this area.
“Earlier diagnosis unlocks access to treatments, support and help sooner. This study suggests blood tests could help detect Alzheimer’s disease in people in their early 60s – a group largely overlooked in previous research, which focused on older adults. While we’re not yet at the point of screening people before symptoms appear, work like this suggests this may be a reality in the future.
“By looking at these biomarkers in a more diverse population, the study made an important step in understanding the potential use of these blood tests for everyone. However, more research is still needed to explore how results may differ depending on a person’s race, sex and genetics.
“Innovative approaches like this and the Blood Biomarker Challenge – led by Alzheimer’s Society, Alzheimer’s Research UK with Postcode Lottery funding – are critical to bringing blood tests for dementia to the NHS in the next five years.”
‘Comparison of [18F] flortaucipir and [18F]MK6240 for the detection of tau pathology in Alzheimer’s disease (HEAD): a multicentre, prospective, cross-sectional, within participant study’ by Guilherme Povala et al. will be published in The Lancet at 23:30 UK time on Thursday 28thMay, which is when the embargo will lift.
‘Alzheimer’s disease neuropathology plasma biomarkers and cognition in midlife: a community-based cohort study’ by Xiaqing Jiang et al. will be published in The Lancet at 23:30 UK time on Thursday 28th May, which is when the embargo will lift.
Declared interests
Prof Roslyn Bill: I am a founder and shareholder in Estuar Pharmaceuticals.
Prof Paresh Malhotra: National Specialty Lead for Dementia and Neurodegeneration, NIHR Research Delivery Network
Honorary Consultant Neurologist, Imperial College Healthcare NHS Trust
Group Leader, UK Dementia Research Institute
Serviced Practice Consultant Neurologist, Cleveland Clinic London
NHSE Working Group Member (Lecanemab and Amyloid PET)
Task and Finish Group, Modern Service Framework for Frailty and Dementia
Trustee, Alzheimer’s Society
Clinical Committee, ARUK
Recipient of ‘Drugs Only’ Grant for NIHR funded Trial, Shire/Takeda
Independent Data Monitoring Committee, J&J
Research funding from NIHR, ARUK, Alzheimer’s Society, MRC, DPUK, BHF, Lifearc, FIFA, FA, UK DRI
Prof Tara Spires-Jones: I have no conflicts with this study but have received payments for consulting, grant reviews, scientific talks, or collaborative research over the past 10 years from AbbVie, Sanofi, Merck, Autifony, Scottish Brain Sciences, Jay Therapeutics, Cognition Therapeutics, Ono, Novo Nordisk, Eisai, Boehringer Ingelheim, and Bristol-Meyers Squibb and direct a company Spires-Jones Neuroscience, Ltd to act as a consultant. I am also Charity trustee for the British Neuroscience Association and the Guarantors of Brain and serve as scientific advisor to several charities and non-profit institutions. My group receives grant funding for research from the UK Dementia Research Institute, Alzheimer’s Research UK, Alzheimer’s Society, Wellcome Trust, Medical Research Council, and the Foundations for the National Institutes of Health.
Dr Jacqui Hanley: “There are no conflicts of interest to declare.”
Dr Richard Oakley: No interests to declare.