Deyan Georgiev / EyeEm / Getty 
 
 A blood test can detect whether plaques of beta-amyloid are building up in a person’s brain – a sign that they may develop Alzheimer’s disease. 
 
 People with Alzheimer’s disease tend to have sticky clumps of beta-amyloid in their brains, although the part these plaques play in the condition is unclear. Until now, the only way to monitor plaque build-up in a person’s brain has been through expensive PET-scans, or by performing an invasive spinal tap procedure. 
 
 Now a team has developed a simple blood test that may make it possible for family doctors to screen for Alzheimer’s risk during health check-ups. “This kind of test could be used to screen many thousands of patients to identify those at risk for Alzheimer’s disease, and to start treatments before memory loss and brain damage,” says Randall Bateman, of Washington University in St Louis, who unveiled the test at the Alzheimer’s Association International Conference in London today. 
 
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 When will we cure Alzheimer’s and Parkinson’s? Learn more at New Scientist Live in London 
 
 Bateman says the test could be used in a similar way to annual checks on cholesterol. The test works by measuring the relative amounts of different forms of beta-amyloid, a sign of whether plaques are likely to be building in a person’s brain. They developed the test by comparing ratios of beta-amyloid types in 41 people’s blood with PET scans showing how much beta-amyloid had aggregated in their brains. 
 
 Early detection 
 
 The hunt for a drug that can effectively treat Alzheimer’s disease continues, but in the meantime, evidence is growing that healthy lifestyle interventions – such as exercise and healthy diet – can reduce the risk of developing the disease by as much as 30 per cent. In theory, the blood test could reassure some people that they are not at risk of developing the condition, while identifying others who might benefit from further tests and lifestyle changes. 
 
 Amyloid plaques start developing 15 to 20 years before the symptoms of Alzheimer’s disease start to show, and testing positive wouldn’t mean that a person is definitely going to develop the condition. 
 
 “I’m very positive about the test, but would like to see it validated,” says Dean Hartley of the Alzheimer’s Association. “It was a very small sample, and they’re trying to confirm it in an additional 180 people.” 
 
 “But in time, if we can get a blood test, it will take us further, just as cholesterol tests did in the cardiovascular field,” says Hartley. ||||| A significant portion of people with mild cognitive impairment or dementia who are taking medication for Alzheimer’s may not actually have the disease, according to interim results of a major study underway to see how PET scans could change the nature of Alzheimer’s diagnosis and treatment. 
 
 The findings, presented Wednesday at the Alzheimer’s Association International Conference in London, come from a four-year study launched in 2016 that is testing over 18,000 Medicare beneficiaries with mild cognitive impairment (MCI) or dementia to see if their brains contain the amyloid plaques that are one of the two hallmarks of the disease. 
 
 So far, the results have been dramatic. Among 4,000 people tested so far in the Imaging Dementia-Evidence for Amyloid Scanning (IDEAS) study, researchers from the Memory and Aging Center at the University of California at San Francisco found that just 54.3 percent of MCI patients and 70.5 percent of dementia patients had the plaques. 
 
 A positive test for amyloid does not mean someone has Alzheimer’s, though its presence precedes the disease and increases the risk of progression. But a negative test definitively means a person does not have it. 
 
 The findings could change the way doctors treat people in these hard-to-diagnose groups and save money being spent on inappropriate medication. 
 
 (National Institute of Biomedical Imaging and Bioengineering) 
 
 “If someone had a putative diagnosis of Alzheimer’s disease, they might be on an Alzheimer’s drug like Aricept or Namenda,” said James Hendrix, the Alzheimer Association’s director of global science initiatives who co-presented the findings. “What if they had a PET scan and it showed that they didn’t have amyloid in their brain? Their physician would take them off that drug and look for something else.” 
 
 For decades, diagnosing Alzheimer’s has been a guessing game, based on looking at a person’s symptoms rather than testing for definitive evidence of the brain disorder. A firm diagnosis was not possible until an autopsy was performed. 
 
 Now, a spinal tap or PET scan can detect the telltale amyloid deposits, and researchers are trying to develop a simple blood test that would do so. PET imaging can quantify the amount of amyloid and also show where it is in a person’s brain. 
 
 But spinal taps are invasive, and PET scans cost $3,000 to $4,000 and are typically not covered by insurance. In 2013 the Centers for Medicare & Medicaid Services (CMS) declined to cover the tests, citing insufficient evidence that they would make a difference for patients with a disease for which there is no cure and limited treatment available. 
 
 But CMS agreed to fund the bulk of the $100 million IDEAS study by reimbursing participants for their PET scans, and researchers hope positive results will persuade them to cover it in the future. 
 
 Over 400 physicians enrolled their patients in the study, and they initially filled out forms describing how they would care for them based on their clinical symptoms. After seeing the PET imaging results, they changed their care plans for two-thirds of the patients in the study. 
 
 “We thought we would be able to see about a 30 percent change, but we’re getting a 66 percent change, so it’s huge,” Hendrix said. “We see high percentages of people who are on a drug and didn’t need to be on those drugs.” 
 
 (Gillian Brockell/The Washington Post) 
 
 Also on Wednesday, the Alzheimer’s Association announced the launch of a $20 million two-year clinical trial to see if lifestyle changes can prevent cognitive decline. 
 
 Modeled after a larger 2014 study in Finland that showed positive results, the U.S. POINTER study will work with 2,500 older adults at risk for cognitive decline. It will test whether two years of intervention that includes physical exercise, nutritional counseling, social and cognitive stimulation, and improved self-management will help cognitive function in participants 60 to 79 years old. 
 
 Similar studies are also underway in Singapore and Australia. 
 
 Research has shown that each of these factors contributes to cognitive health, but researchers believe that, as with heart disease, combating Alzheimer’s is likely to require a multipronged, or “cocktail” approach combining drugs and lifestyle changes. ||||| In this photo taken July 12, 2017, Cynthia Guzman plays dominoes at her home in Napa, Calif. Guzman underwent a special kind of PET scan that can detect a hallmark of Alzheimer’s and learned she didn’t... (Associated Press) 
 
 WASHINGTON (AP) — Does it really take an expensive brain scan to diagnose Alzheimer's? Not everybody needs one but new research suggests that for a surprising number of patients whose memory problems are hard to pin down, PET scans may lead to changes in treatment. 
 
 The findings, reported Wednesday, mark a first peek at a huge study under way to help determine if Medicare should start paying for specialized PET scans that find a hallmark of Alzheimer's — a sticky plaque called amyloid. 
 
 Alzheimer's is the most common form of dementia, and classic symptoms plus memory tests often are enough for a reliable diagnosis. But unusual symptoms could mark another form of dementia that, while there are no cures, could require different symptom care. And on the other end of the spectrum, it's hard to tell if mild memory loss might be an early Alzheimer's signal, a more treatable condition such as depression, or even age-related decline. 
 
 "We're not accurate enough," said Dr. Gil Rabinovici of the University of California, San Francisco, who is leading the new research. 
 
 "Patients know there's something wrong. Often they can sense in their gut that it's not normal aging," he added. Without a clear-cut test, "doctors are very reluctant to make the diagnosis in many cases." 
 
 Until a few years ago, amyloid build-up could only be seen during autopsies. Older types of PET scans show what region of the brain appears most affected, of limited help. 
 
 Yet it's not clear how best to use the new amyloid-detecting scans, which can cost up to $6,000. They can rule out Alzheimer's if there's little amyloid. But cognitively healthy seniors can harbor amyloid, too, and Medicare won't pay for the new scans outside of a few research studies. 
 
 One of those is the IDEAS study, which is testing the impact of amyloid-detecting PET scans in more than 18,000 Medicare beneficiaries. To enroll, patients either must have atypical dementia with an unclear cause — or have particularly puzzling "mild cognitive impairment," or MCI, early memory problems that raise the risk of later developing dementia. Researchers check if doctors' initially recorded treatment plans — medications, counseling or additional testing — were altered by patients' PET results. 
 
 That happened in about two-thirds of the cases, according to preliminary findings from nearly 4,000 patients who were the first to enroll. 
 
 Most changes involved medications that can temporarily ease Alzheimer's symptoms, said Rabinovici, who presented the findings at the Alzheimer's Association International Conference in London. The PET scans found 70 percent of the dementia patients indeed had amyloid build-up, pointing out those who might benefit from those drugs and those who won't. 
 
 More intriguing, just 54 percent of the MCI patients had amyloid build-up, putting them at higher risk for later Alzheimer's. For the rest, "Alzheimer's disease was effectively ruled out, so it's something else," Rabinovici said. 
 
 The early findings don't prove PETs affect health outcomes. 
 
 But the Centers for Medicare and Medicaid Services helped plan the research and insisted on this midpoint check to be sure the study should continue, said Maria Carrillo, the Alzheimer's Association's chief medical officer. Researchers also will compare the 18,000 study participants with Medicare records of similar patients who didn't get PET scans, seeking final evidence of benefit. 
 
 "To get that right diagnosis, that's really important," said Cynthia Guzman of Napa, California, whose initial Alzheimer's diagnosis was ruled out in an earlier PET scan study. 
 
 Guzman had unusual fluctuating memory problems. Some days she functioned normally. Others, she'd stop her car at a stop sign without knowing how she got there or where she was going. Eventually, tremors and hallucinations led specialists to conclude she has Lewy body dementia. Knowing, Guzman said, has allowed her to avoid a list of common medications that could worsen her symptoms. 
 
 While any treatment changes today may be modest, researchers are hunting drugs that eventually might at least slow Alzheimer's rather than just treat symptoms, more impetus for a precise diagnosis. 
 
 "We all hope for a day when this will be critically important," said Dr. Richard Hodes, director of the National Institute on Aging, who wasn't involved with the IDEAS study. 
 
 For now, in addition to people who qualify for the IDEAS study, the Alzheimer's Association and Society of Nuclear Medicine and Molecular Imaging say: 
 
 —Unusually young dementia patients, younger than 65, also might be candidates for a PET scan. 
 
 —The scans shouldn't be used as a screening tool for people without symptoms or who worry they're at risk. 
 
 —Nor are they for people who can be diagnosed by standard means, or to determine disease severity.
– Diagnosing Alzheimer's is a guessing game—and many doctors are guessing wrong, according to early results from a new study presented Wednesday in London. The Washington Post reports doctors tested 4,000 Medicare patients with mild cognitive impairment or dementia and discovered many of them definitively do not have Alzheimer's. Using PET scans, the study revealed only 54.3% of mild cognitive impairment patients and 70.5% of dementia patients had brains containing amyloid plaques. These plaques can be a sign of Alzheimer's. The patients who had them may or may not have Alzheimer's; the remaining percentage definitely don't have the disease. "To get that right diagnosis, that's really important," one woman, whose Alzheimer's diagnosis was ruled out by a PET scan, tells the AP. The findings show many people are potentially taking unnecessary Alzheimer's medication, and doctors may want to change their treatment to something cheaper or more effective. Unfortunately, the only ways to test for amyloid plaques while a patient is alive are expensive PET scans, which aren't usually covered by insurance, or invasive spinal taps. Or are they? Another study presented at the same London conference revealed a new blood test that could potentially reveal the plaques, New Scientist reports. The tests are easy and cheap enough that doctors could administer them to patients during regular checkups. Since plaques start showing up 15 to 20 years before Alzheimer's symptoms, patients could use the results to change certain lifestyle habits to decrease their risk. (This startup buys young blood, injects it into older people.)