One in 10 people in the UK aged 70 and older could have Alzheimer’s-like changes in their brain, according to the clearest, real-world picture of how common the disease’s brain changes are in ordinary, older people.
The detection of the proteins linked with the disease is not a diagnosis. But the findings indicate that more than 1 million over-70s would meet Nice’s clinical criteria for anti-amyloid therapy – a stark contrast to the 70,000 people the NHS has estimated could be eligible if funding were available.
Experts, including those from Alzheimer’s Research UK, have said the findings from the first-ever population-based research into the disease have huge potential for early and accurate diagnosis.
“High-quality studies like this are crucial to enhancing our understanding of how blood tests for Alzheimer’s could be used in clinical practice,” said David Thomas, the head of policy and public affairs at Alzheimer’s Research UK. “We need to generate more evidence so we can use these tests in the NHS.”
The lead author of the research, conducted by King’s College London, Stavanger University hospital and the University of Gothenburg, said the findings could be a “gamechanger in the understanding of the disease”.
The findings also challenge some long-held assumptions about dementia, including the idea that it is mainly a disease that mainly affects women.
Dag Aarsland, a professor of old age psychiatry at the Institute of Psychiatry, Psychology and Neuroscience at King’s College London and the study’s lead author, said: “In an ageing global population, the assessment and treatment of dementia presents a significant challenge. Our study used a simple blood test to establish changes that contribute to cognitive impairment in those with dementia
Previous estimates have relied on small clinic-based samples or research cohorts, leaving uncertainty about how common these brain changes are in the general population. But the new study, published on 17 December in Nature, used blood biomarker data from almost 11,500 people drawn at random.
The p-tau217 blood test used was recently cleared by regulators and can identify Alzheimer’s much earlier than previously possible.
The study measures only current brain changes and so does not show who will develop dementia. Aarsland said this would be his next area of research. He also wants to work with GPs to find out how these tests, which are not available on the NHS, can be used in primary care.
“This data is very interesting, strong and accurate, and is an important extension to what we know,” said Tara Spires-Jones, a professor of neurodegeneration and the director of the Centre for Discovery Brain Sciences at the University of Edinburgh.
“Treatment are currently not available on the NHS because they’re so expensive and risky. But as these get better over the next few years it’s important that we can find people with amyloid in their brain using an easy test,” she said.
Eric Brunner, a professor of social and biological epidemiology at University College London, said the research showed scientists were “entering a new era when dementia is no longer something where we’re powerless to treat”.
“The paper is very valuable, because it shows that we can identify people before they develop clinical dementia,” he said. “But the sheer numbers emphasise the fact that the NHS can in no way afford to treat all those who could benefit at the current cost.”
The study is the first to provide direct, real-life numbers for how common Alzheimer’s changes are by age. Fewer than 8% of people in their 50s and 60s carry the marker, just over a third of those in their 70s, and about two-thirds of people over 90.
Currently, nearly 1 million people in the UK live with dementia, and about one in 14 of those are 65 and over. That number is expected to rise to about 1.4 million by 2040. This figure does not include people with early Alzheimer’s brain changes who have not yet developed dementia.
