Image copyright SPL 
 
 A blood test can accurately predict the onset of Alzheimer's disease, according to US researchers. 
 
 They showed that testing levels of 10 fats in the blood could predict - with 90% accuracy - the risk of the disease coming on in the next three years. 
 
 Their findings, published in Nature Medicine, will now be tested in larger clinical trials. 
 
 Experts said the results needed to be confirmed, but such a test would be "a real step forward". 
 
 The number of people living with dementia stands at 44 million around the globe and is expected to treble by 2050. 
 
 The disease silently attacks the brain for more than a decade before any symptoms emerge. Doctors think drug trials are failing because patients are simply being treated too late to make a difference. 
 
 This is why discovering a test that predicts the risk of dementia is a major priority for the field. 
 
 Image copyright SPL Image caption Loss of tissue in a demented brain compared with a healthy one 
 
 Blood clues 
 
 Scientists at Georgetown University in Washington DC analysed blood samples from 525 people over the age of 70 as part of a five-year study. 
 
 They took 53 of them who developed Alzheimer's or mild cognitive impairment and compared their blood with 53 who stayed mentally agile. 
 
 They found differences in the levels of 10 lipids, or fats, between the two groups. 
 
 And when the research team looked in the other blood samples, those 10 markers of Alzheimer's could predict who was likely to enter mental decline in the following years. 
 
 Media caption Dementia specialist Dr Iracema Leroi explains the significance of the research 
 
 Howard Federoff, professor of neurology at Georgetown University Medical Center, told the BBC: "I think there is a huge need for a test. 
 
 "But we must look at larger numbers of people before this could be used in clinical practice." 
 
 The full power of the test has not been investigated either. So far they know a diagnosis of dementia can be predicted three years ahead of time, but the researchers are now investigating whether the test works even earlier. 
 
 It is not clear exactly what is causing the change in fats in the blood, but it could be a residue of the early changes in the brain. 
 
 Dementia across the globe 44 million globally have dementia 
 
 135 million will have the disease in 2050 
 
 By then 71% will be poor and middle income 
 
 $600bn global cost of dementia 
 
 In the UK, cancer research gets 8x as much funding as dementia Source: Alzheimer's Society 
 
 A successful test for Alzheimer's could transform medical research and treatment drugs could be tested at a much earlier stage in the disease. 
 
 Prof Federoff said slowing the pace of the disease could have a huge impact: "Even a short delay of symptoms will have a tremendous economic benefit just in terms of the cost of care." 
 
 Media caption Alzheimer's Research UK's Dr Simon Ridley: Blood test claims "too optimistic" 
 
 Dr Simon Ridley, from the charity Alzheimer's Research UK, said the findings were "encouraging" and that a blood test would be a "real step forward". 
 
 What is dementia? It is an umbrella term that describes about 100 diseases in which brain cells die on a huge scale 
 
 All damage memory, language, mental agility, understanding and judgement 
 
 Alzheimer's disease is the most common form, affecting 62% of those living with dementia 
 
 It gets worse with time and eventually people are left completely dependent on carers 
 
 It is incurable World dementia cases 'set to treble' The dementia timebomb 
 
 He added: "To test the effectiveness of potential new drugs, it's important to be able to recruit people to clinical trials in the early stages of the disease, when such treatments are most likely to be effective. 
 
 "If confirmed, these results could also aid efforts to develop better tools for diagnosing Alzheimer's - allowing people with the disease to access crucial support and existing treatments sooner." 
 
 The Alzheimer's Society's Dr Doug Brown said the test needed to be investigated further, but could pose ethical challenges. 
 
 "If this does develop in the future people must be given a choice about whether they would want to know, and fully understand the implications." 

 Your Health 
 
 Alzheimer's Blood Test Raises Ethical Questions 
 
 itoggle caption iStockphoto 
 
 An experimental blood test can identify people in their 70s who are likely to develop Alzheimer's disease within two or three years. The test is accurate more than 90 percent of the time, scientists reported Sunday in Nature Medicine. 
 
 The finding could lead to a quick and easy way for seniors to assess their risk of Alzheimer's, says Dr. Howard Federoff, a professor of neurology at Georgetown University. And that would be a "game changer," he says, if researchers find a treatment that can slow down or stop the disease. 
 
 But because there is still no way to halt Alzheimer's, Federoff says, people considering the test would have to decide whether they are prepared to get results that "could be life-altering." 
 
 The idea of predicting Alzheimer's isn't new. It's already possible to detect signs of the disease long before symptoms like memory loss begin to appear. But the tests require either a spinal tap, which is painful, or an MRI scan, which is time consuming and expensive. 
 
 So Federoff and a team of researchers set out to find something better. They took blood samples from 525 people ages 70 and older. Then, he says, they looked to see who developed Alzheimer's in the next five years. 
 
 The goal was to find some difference between the blood of people who developed Alzheimer's and the blood of people who remained "cognitively normal," Federoff says. And after sifting through more than 4,000 potential "biomarkers," he says, "We discovered that 10 blood lipids [fats] predicted whether someone would go on to develop cognitive impairment or Alzheimer's." 
 
 The results need to be confirmed, and the approach still needs to be tried in people of different ages and from different racial groups, Federoff says. Even so, he says, it raises the possibility that in the not too distant future, many more people will know their risk of Alzheimer's. 
 
 That knowledge can be a good thing, says Dr. Jason Karlawish, a professor of medicine, medical ethics and health policy at the University of Pennsylvania. That's been shown among people who chose to be tested for a gene that increases the risk of Alzheimer's, he says. 
 
 "Knowing their risk of developing cognitive impairment is very relevant to making plans around retirement and where they live," he says. "So there is certainly a role for knowing that information." 
 
 On the other hand, people who have the Alzheimer's gene and know it tend to rate their own memories as worse than people who have the gene but don't know it, he says. Knowing you carry the gene also seems to hurt people's performance on memory tests. 
 
 But the biggest concern about Alzheimer's testing probably has to do with questions of stigma and identity, Karlawish says. "How will other people interact with you if they learn that you have this information?" he says. "And how will you think about your own brain and your sort of sense of self?" 
 
 The stigma and fear surrounding Alzheimer's may decrease, though, as our understanding of the disease changes, Karlawish says. Right now, people still tend to think that "either you have Alzheimer's disease dementia or you're normal, you don't have it," he says. 
 
 But research has shown that's not really true, Karlawish says. Alzheimer's is a bit like heart disease. It starts with biological changes that occur years before symptoms appear. And there is no bright line separating healthy people from those in early stages of the disease.
– A simple blood test can spot Alzheimer's disease years before symptoms develop, researchers say—though it's a breakthrough some may choose to ignore. A Georgetown University team says its "highly sensitive and specific test" can identify people in their 70s who are likely to develop Alzheimer's in the next two to three years, reports the BBC. They tested levels of 10 fats in the blood to get results they say are 90% accurate. It's already possible to spot the disease early with MRI scans or spinal taps, but the researchers say a quick and easy test could be a "game changer" that will help efforts to find ways to slow down or stop the disease. If larger-scale tests confirm the breakthrough, many seniors will have to ask themselves whether they are prepared to face what the lead researcher calls test results that "could be life-altering," NPR finds. No cure for Alzheimer's exists, and while knowing they will soon develop the disease would help people plan ahead for their needs, they would face major questions of stigma and identity, medical ethicist notes. "How will other people interact with you if they learn that you have this information?" he says. "And how will you think about your own brain and your sort of sense of self?"