Alzheimer’s is a fatal disease. Over 5 million people in the U.S. currently live with Alzheimer’s, and most have a life expectancy of 3 to 10 years after diagnosis. With that number in mind, how were only 83,494 deaths attributed to Alzheimer’s in 2010? The numbers just don’t add up.
That’s because we’ve been counting incorrectly all along, according to a new study published Wednesday in the journal Neurology. Alzheimer’s is so dramatically underreported as “cause of death” on death certificates, the study says, that it estimates 503,400 people actually died of the disease in 2010, six times more than the official figure. To put that in perspective, 597,689 people in the U.S. died of heart disease that year, and 574,743 died of cancer, according to the CDC. Those are currently the leading and second-leading causes of death in the country.
The disparity lies with how death certificates are filled out: if an Alzheimer’s patient dies of pneumonia, the death certificate will likely only state “pneumonia” as the cause of death. But that doesn’t take into account Alzheimer’s may have made it impossible for that person to recover from the pneumonia.
“Many people unfortunately think that people suffer through Alzheimer’s and then they eventually die of old age,” Dr. Bryan D. James, an epidemiologist at Rush University Medical Center in Chicago and lead author of the study, tells Newsweek. “In actuality, Alzheimer’s starts in the part of the brain that controls your memory and thinking. Over years it moves to other parts of the brain that affects breathing, swallowing, and heart rate. That’s the piece that many people don’t get. They don’t think that it’s a killer.”
The study’s researchers followed 2,566 people aged 65 and older for eight years. The found death rate over that period was more than four times higher for people who developed Alzheimer's among those age 75 to 84, and nearly three times higher in people age 85 and older. More than one-third of all deaths for those age groups were due to Alzheimer’s.
“I don’t think many people in the Alzheimer’s world will be that surprised by this number,” James says. “Most people recognize that the number of deaths are drastically under-recorded for this disease.”
The diseases that are known as the largest killers tend to get the most research funding, James says. So at sixth place in terms of mortality rates, Alzheimer’s is relatively underfunded compared to cancer and heart disease.
“One of the motivations for writing this is just for that reason, to open the public’s eye, and the government’s eye, and maybe to shape some priorities for funders.”
The new estimated death rate for Alzheimer’s would make the disease the third most deadly in the United States.
“Every little scoop of water that adds to the wave builds the momentum” for more Alzheimer’s funding, James says.