A staggering 1 in 3 seniors dies with Alzheimer's disease or other types of dementia, says a new U.S. report that highlights the impact the mind-destroying disease is having on the rapidly aging population.

Dying with Alzheimer's is not the same as dying from it. But even when dementia isn't the direct cause of death, it can be the final blow — speeding someone's decline by interfering with their care for heart disease, cancer or other serious illnesses. That's the assessment of the report released Tuesday by the Alzheimer's Association, which advocates for more research and support for families afflicted by it.

The Alzheimer's Society of Canada projects that the number of cases will more than double to 1.25 million by 2038. (Enrique Castro-Mendivil/Reuters)

"Exacerbated aging," is how Dr. Maria Carrillo, an association vice president, terms the Alzheimer's effect. "It changes any health care situation for a family."

In fact, only 30 per cent of 70-year-olds who don't have Alzheimer's are expected to die before their 80th birthday. But if they do have dementia, 61 per cent are expected to die, the report found.

Already, 5.2 million Americans have Alzheimer's or some other form of dementia. Those numbers will jump to 13.8 million by 2050, Tuesday's report predicts. That's slightly lower than some previous estimates.

Count just the deaths directly attributed to dementia, and they're growing fast. Nearly 85,000 people died from Alzheimer's in 2011, the U.S. Centers for Disease Control and Prevention estimated in a separate report Tuesday. Those are people who had Alzheimer's listed as an underlying cause on a death certificate, perhaps because the dementia led to respiratory failure. Those numbers make Alzheimer's the sixth leading cause of death.

That death rate rose 39 per cent in the past decade, even as the CDC found that deaths declined among some of the nation's other top killers — heart disease, cancer, stroke and diabetes. The reason: Alzheimer's is the only one of those leading killers to have no good treatment. Today's medications only temporarily ease some dementia symptoms.

But what's on a death certificate is only part of the story.

Consider: Severe dementia can make it difficult for people to move around or swallow properly. That increases the risk of pneumonia, one of the most commonly identified causes of death among Alzheimer's patients.

Likewise, dementia patients can forget their medications for diabetes, high blood pressure or other illnesses. They may not be able to explain they are feeling symptoms of other ailments such as infections. They're far more likely to be hospitalized than other older adults. That in turn increases their risk of death within the following year.

"You should be getting a sense of the so-called blurred distinction between deaths among people with Alzheimer's and deaths caused by Alzheimer's. It's not so clear where to draw the line," said Jennifer Weuve of Chicago's Rush University, who helped study that very question.

The Chicago Health and Aging Project tracked the health of more than 10,000 older adults over time. Weuve's team used the data to estimate how many people nationally will die with Alzheimer's this year — about 450,000, according to Tuesday's report.

That's compatible with the 1 in 3 figure the Alzheimer's Association calculates for all dementias. That number is based on a separate analysis of Medicare data that includes both Alzheimer's cases and deaths among seniors with other forms of dementia.

Last year, the Obama administration set a goal of finding effective Alzheimer's treatments by 2025, and increased research funding to help. It's not clear how the government's automatic budget cuts, which began earlier this month, will affect those plans.