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. ||||| Researchers report that a spinal fluid test can be 100 percent accurate in in identifying a signature level of abnormal proteins in patients with significant memory loss who went on to develop Alzheimer’s disease . 
 
 Although there has been increasing evidence of the value of this and other tests in finding signs of Alzheimer’s, the study, which will appear Tuesday in the Archives of Neurology, shows how accurate they can be. The new result is one of a number of remarkable recent findings about Alzheimer’s. 
 
 After decades when nothing much seemed to be happening, when this progressive brain disease seemed untreatable and when its diagnosis could be confirmed only at autopsy, the field has suddenly woken up. 
 
 Alzheimer’s, medical experts now agree, starts a decade or more before people have symptoms. And by the time there are symptoms, it may be too late to save the brain. So the hope is to find good ways to identify people who are getting the disease, and use those people as subjects in studies to see how long it takes for symptoms to occur and in studies of drugs that may slow or stop the disease. 
 
 Researchers are finding simple and accurate ways to detect Alzheimer’s long before there are definite symptoms. In addition to spinal fluid tests they also have new PET scans of the brain that show the telltale amyloid plaques that are a unique feature of the disease. And they are testing hundreds of new drugs that, they hope, might change the course of the relentless brain cell death that robs people of their memories and abilities to think and reason. 
 
 “This is what everyone is looking for, the bull’s-eye of perfect predictive accuracy,” Dr. Steven DeKosky, dean of the University of Virginia medical school, who is not connected to the new research, said about the spinal tap study. 
 
 Dr. John Morris, a professor of neurology at Washington University, said the new study “establishes that there is a signature of Alzheimer’s and that it means something. It is very powerful.” 
 
 A lot of work lies ahead, researchers say — making sure the tests are reliable if they are used in doctors’ offices, making sure the research findings hold up in real-life situations, getting doctors and patients comfortable with the notion of spinal taps, the method used to get spinal fluid. But they see a bright future. 
 
 Although the latest PET scans for Alzheimer’s are not commercially available, the spinal fluid tests are. 
 
 So the new results also give rise to a difficult question: Should doctors offer, or patients accept, commercially available spinal tap tests to find a disease that is yet untreatable? In the research studies, patients are often not told they may have the disease, but in practice in the real world, many may be told. 
 
 Some medical experts say it should be up to doctors and their patients. Others say doctors should refrain from using the spinal fluid test in their practices. They note that it is not reliable enough — results can vary by lab — and has been studied only in research settings where patients are carefully selected to have no other conditions, like strokes or depression, that could affect their memories. 
 
 “This is literally on the cutting edge of where the field is,” Dr. DeKosky said. “The field is moving fast. You can get a test that is approved by the F.D.A., and cutting edge doctors will use it.” 
 
 But, said Dr. John Trojanowski, a University of Pennsylvania researcher and senior author of the paper, given that people can get the test now, “How early do you want to label people?” 
 
 Some, like Dr. John Growdon, a neurology professor at Massachusetts General Hospital who wrote an editorial accompanying the paper, said that decision was up to doctors and their patients. 
 
 Sometimes patients with severe memory loss do not have the disease. Doctors might want to use the test in cases where they want to be sure of the diagnosis. And they might want to offer the test to people with milder symptoms who want to know whether they are developing the devastating brain disease. 
 
 One drawback, though, is that spinal fluid is obtained with a spinal tap, and that procedure, with its reputation for pain and headaches, makes most doctors and many patients nervous. The procedure involves putting a needle in the spinal space and withdrawing a small amount of fluid. 
 
 Dr. Growdon and others say spinal taps are safe and not particularly painful for most people. But, he said, there needs to be an education campaign to make people feel more comfortable about having them. He suggested that, because most family doctors and internists are not experienced with the test, there could be special spinal tap centers where they could send patients. 
 
 The new study included more than 300 patients in their 70s, 114 with normal memories, 200 with memory problems and 102 with Alzheimer’s disease. Their spinal fluid was analyzed for amyloid beta, a protein fragment that forms plaques in the brain, and for tau, a protein that accumulates in dead and dying nerve cells in the brain. To avoid bias, the researchers analyzing the data did not know anything about the clinical status of the subjects. Also, the subjects were not told what the tests showed. 
 
 Nearly every person with Alzheimer’s had the characteristic spinal fluid protein levels. Nearly three quarters of people with mild cognitive impairment, a memory impediment that can precede Alzheimer’s, had Alzheimer’s-like spinal fluid proteins. And about a third of people with normal memories had spinal fluid indicating Alzheimer’s. Researchers suspect that those people will develop memory problems. 
 
 In checking their findings against data gathered in a separate study, the researchers found that among 57 patients with mild cognitive impairment who went on to develop Alzheimer’s within five years, 100 percent had the characteristic protein levels five years before. 
 
 The prevailing hypothesis about Alzheimer’s says that amyloid and tau accumulation are necessary for the disease and that stopping the proteins could stop the disease. But it is not yet known what happens when these proteins accumulate in the brains of people with normal memories. They might be a risk factor like high cholesterol levels. Many people with high cholesterol levels never have heart attacks. Or it might mean that Alzheimer’s has already started and if the person lives long enough he or she will with absolute certainty get symptoms like memory loss. 
 
 Many, like Dr. DeKosky, believe that when PET scans for amyloid become available, they will be used instead of spinal taps, in part because doctors and patients are more comfortable with brain scans. 
 
 And when — researchers optimistically are saying “when” these days — drugs are shown to slow or prevent the disease, the thought is that people will start having brain scans or spinal taps for Alzheimer’s as routinely as they might have colonoscopies or mammograms today. 
 
 For now, Dr. DeKosky said, the days when Alzheimer’s could be confirmed only at autopsy are almost over. And the time when Alzheimer’s could be detected only after most of the brain damage was done seem to be ending, too. 
 
 “The new biomarkers in CSF have made the difference,” Dr. DeKosky said, referring to cerebral spinal fluid. “This confirms their accuracy in a very big way.”
– 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.)