One in 10 people in the UK aged 70 and over could have Alzheimer's-like brain changes, according to the clearest, real-life picture of how common brain changes caused by the disease are in ordinary older people.
Finding proteins associated with a disease does not constitute a diagnosis. But the results show that more than 1 million people over 70 meet the Nice clinical criteria for anti-amyloid therapy – a stark contrast to the 70,000 people the NHS estimates would be eligible for treatment if funding were available.
Experts including Alzheimer's Research UK said: conclusions The results of the first ever population-based study of this disease have enormous potential for early and accurate diagnosis.
“High-quality research like this is critical to improving our understanding of how blood tests for Alzheimer's disease can be used in clinical practice,” said David Thomas, head of policy and public affairs at Alzheimer's Research UK. “We need to gather more evidence so we can use these tests in the NHS.”
The lead author of the study, led by King's College London, Stavanger University Hospital and the University of Gothenburg, said the findings could be a “game-changer in understanding the disease.”
The findings also challenge some long-held assumptions about dementia, including the idea that the disease primarily affects women.
Dag Aarsland, Professor of Old Age Psychiatry at the Institute of Psychiatry, Psychology and Neurology from King's College London and lead author of the study said: “With an aging global population, the assessment and treatment of dementia poses a major challenge. Our study used a simple blood test to identify changes that contribute to cognitive impairment in people with dementia.”
Previous estimates were based on small samples in clinics or research cohorts, leaving uncertainty about how common these brain changes are in the general population. But the new study, published Dec. 17 in the journal Nature, used blood biomarker data from nearly 11,500 randomly selected people.
The p-tau217 blood test used was recently approved by regulators and can detect Alzheimer's disease much earlier than previously possible.
The study only measures ongoing changes in the brain and therefore does not show who will develop dementia. Aarsland said this will 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.
“These data are very interesting, compelling and precise and are an important extension of what we know,” said Tara Spiers-Jones, professor of neurodegeneration and director of the Center for Brain Research at the University of Edinburgh.
“The treatment is not currently available on the NHS because it is so expensive and risky. But as the situation improves over the next few years, it is important that we can find people with amyloid in the brain with a simple test,” she said.
Eric Brunner, professor of social and biological epidemiology at University College London, said the study showed scientists are “entering a new era where dementia is no longer something we are powerless to cure.”
“The work is very valuable because it shows that we can identify people before they develop clinical dementia,” he said. “But the figures themselves highlight the fact that there is no way the NHS can afford to treat all those who could benefit at current costs.”
The study is the first to provide direct, real-world numbers on how common Alzheimer's disease changes are as a function of age. Less than 8% of people aged 50 to 60 carry this marker, just over a third of people aged 70 and about two thirds of people over 90.
Almost 1 million people in the UK are currently living with dementia. This number is expected to rise to approximately 1.4 million by 2040. This figure does not include people with early brain changes caused by Alzheimer's disease who have not yet developed dementia.
