Alzheimer's deaths much more common than realized: study
NEW YORK - Nearly half a million elderly Americans likely died from Alzheimer's disease in 2010, a figure almost six times higher than previous estimates of annual deaths, according to a new study released Wednesday.
"Many people do not realize that Alzheimer's is a fatal disease," said lead author Bryan D. James of the Rush Alzheimer's Disease Center in Chicago.
"Alzheimer's disease starts in the part of your brain that controls your memory and thinking, but over years it spreads to the parts of your brain that control more basic functions such as breathing and swallowing," he said.
Current national estimates - 83,000 Alzheimer's deaths a year - are based on death certificates, which tend to underestimate deaths from dementia, James' team writes in the journal Neurology.
They analyzed data from two existing studies - one involving nuns and priests, the other residents of housing for seniors and retirees - that followed people age 65 and older, starting before they had any symptoms of Alzheimer's. The participants were tracked an average of eight years, with annual checkups and brain donation in the case of death.
Overall, 559 of the 2,566 participants developed Alzheimer's, living an average of four years after diagnosis; 1,090 died.
People with Alzheimer's were more than three times as likely to die as those without it, and more than four times as likely among ages 75 to 84.
Applying these figures to U.S. deaths in 2010, when the data in the two studies were collected, the authors estimate that about 500,000 people over age 75 died from Alzheimer's disease that year.
"There's no doubt that if you have Alzheimer's disease, it increases mortality risk," said James Leverenz of the Cleveland Clinic Lou Ruvo Center for Brain Health in Ohio.
Although current national estimates are definitely low, he said, the two study groups were healthier than most Americans and may have been less likely to die from other causes. So a higher proportion might have died from Alzheimer's, skewing the findings upward.