ALZHEIMER DISEASE BURDEN

A new analysis shows that upwards of 500,000 deaths a year, or more than a third in older adults, are due to Alzheimer's disease (AD), making it the third leading cause of death after heart disease and cancer.

That's a far cry from the just over 80,000 deaths that the Centers for Disease Control and Prevention (CDC) attributed to AD in 2010.

It's important to know "the actual toll" of AD from both a scientific and a public policy standpoint, lead author Bryan D. James, PhD, assistant professor, Rush Alzheimer's Disease Center, Chicago, Illinois, told Medscape Medical News.

It has been difficult to estimate mortality truly due to AD because, for example, a death certificate may have pneumonia or some other disorder as a cause of death when in fact AD was the real cause.

"What's horrible about AD is that you lose your personality and your memory slowly over time, and eventually, your brain will shut down and this can lead to your death," said Dr. James. "This is a 100% terminal disease; no one has ever been cured of Alzheimer's."

The study was published online March 5 in Neurology.

Population Attributable Risks

The researchers used data from 2 well-known cohort studies: the Religious Orders Study of older Catholic nuns, priests, and brothers from across the United States and the Rush Memory and Aging Project of older persons living in Illinois. Both studies require brain and tissue donations, with the autopsy rate being almost 90%. For the most part, therefore, the ascertainment of mortality is complete and dates of death accurate, according to the authors.

The pooled analysis included 2566 persons who did not have dementia at baseline.

Over an average 8.0 years of follow-up, AD dementia was diagnosed in 21.8% of the participants. The mean age of incident AD dementia diagnosis was 86.53 years. Also during follow-up, 72% of those who developed AD died, as did 34.5% of those who didn't develop AD.

The chart below shows AD mortality relative to other causes of death according to death certificates in 2010 (Data from CDC). The red star indicates the new number from this study.