Alzheimer 's disease ravages the brain , robbing its victims not only of their memories but often their ability to do things as basic as swallowing . Now , a study of aging patients suggests its true toll may top half a million lives a year -- a figure that would put Alzheimer 's just below heart disease and cancer on the list of America 's top killers . The incurable , degenerative brain disease was blamed for 83,000-plus U.S. fatalities in 2010 , making it the sixth-leading cause of death that year . But its true toll may be as much as six times that , said Bryan James , an epidemiologist at the Rush Alzheimer 's Disease Center in Chicago . `` Death certificates are well known to underreport deaths from Alzheimer 's and other types of dementia , '' said James , the lead author of the study published Wednesday . `` The more immediate causes of death , such as pneumonia or heart attack , are usually listed , and the underlying causes of death are usually left off . '' The eight-year study , published in the peer-reviewed journal Neurology , followed more than 2,500 people over 65 . Of those , nearly a quarter developed Alzheimer 's , and the disease was the cause of death in about 400 people , James said . Overwhelming burden , cost of Alzheimer 's to triple , report says . James and his colleagues -- co-workers at Rush University in Chicago and at two California institutions , the University of California-San Francisco and the Veterans Affairs Medical Center there -- then statistically extrapolated their results to arrive at their estimate of 503,000 Alzheimer 's deaths a year . By comparison , heart disease was blamed for nearly 600,000 deaths in 2010 and cancer about 575,000 -- but those numbers are going down , while deaths from Alzheimer 's are going up . `` I could n't say when , but in the next 20 years , it could catch up to cancer , '' James said . The study was funded by the National Institute on Aging and the Illinois Department of Public Health . Dallas Anderson , who oversees population studies of Alzheimer 's and dementia at the NIA , called the findings `` eye-catching . '' `` People who I think are knowledgeable about the death registration system in the U.S. would not be surprised that the official number is low , but it is somewhat of a surprise to see that kind of a difference , '' Anderson told CNN . Similar studies are under way , and similar results would bolster the findings of James and his colleagues , he said . In the meantime , the results might encourage more doctors to note Alzheimer 's when filling out death certificates -- something an increasing number of physicians have been doing already . `` It 's just another reminder that Alzheimer 's is really an important public health problem , and we need to work on it , '' Anderson said . The 10 warning signs of Alzheimer 's . Keith Fargo , the science program director of the Alzheimer 's Association , said the new study 's mortality estimate is `` much closer to the true number . '' `` The Alzheimer 's Association has been saying for a long time that that 80,000 figure is a gross undercount , '' Fargo said . The new figures may help Americans realize that Alzheimer 's is n't `` just about forgetfulness , '' but `` a universally fatal brain disease . '' `` We think this is a solid paper that really puts the true impact of the disease into perspective , '' he added . The Alzheimer 's Association , which supports more research into causes and treatments , estimates that 5.2 million Americans had Alzheimer 's disease in 2013 . Alzheimer 's deaths went up by 68 % over the past decade as mortality from other major diseases declined , and the association expects the number of people over 65 with the disease to climb to 7.1 million by 2025 . In 2012 , the Obama administration announced plans to pour another $ 156 million into Alzheimer 's research . The National Institutes of Health has about $ 560 million currently budgeted for the work . But the Alzheimer 's Association estimates the disease costs more than $ 200 billion per year -- and since the patients are mostly elderly , much of that is paid by the federal health programs Medicare and Medicaid . The promised increase in research funding is `` a step in the right direction , '' but not enough , Fargo said . `` Scientists have told us we need to invest $ 2 billion a year for 10 years if we are truly going to move the needle on Alzheimer 's disease , '' he said . Alzheimer 's disease fast facts .
A new study suggests Alzheimer 's may be the third - leading leading cause of death . Current figures are ` ` a gross disaster , '' Alzheimer 's Association says . The study followed 2,500 patients for 8 months ; 400 died of Alzheimer 's . Advocates hope the findings will create momentum for more research .