Number of Alzheimer’s deaths found to be underreported

May 22, 2014

Official mortality figures may have substantially underreported deaths due to Alzheimer’s disease in 2010 show two recent studies supported in part by NIA. Underreporting of Alzheimer’s as a cause of death on death certificates is a well-known phenomenon. Some people with the disease never receive a diagnosis. Many others have dementia-related conditions, such as aspiration pneumonia, listed as the primary cause of death while the underlying cause, Alzheimer’s, is never reported.

When a person dies, the cause or causes of death are listed on death certificates, typically by a physician, and filed with the state’s Bureau of Vital Statistics. This information is then forwarded to the National Center for Health Statistics of the Centers for Disease Control and Prevention (CDC), which compiles and reports the totals each year as the official U.S. mortality figures and leading causes of death. The CDC’s tally of 83,494 Alzheimer’s deaths in 2010, based on death certificates, ranks the disease as the sixth leading cause of death.

Two groups of investigators at Rush University, Chicago, wanted to examine this phenomenon to gain a clearer picture of the full burden of Alzheimer’s disease now and in the decades to come. While their estimates of deaths due to Alzheimer’s in 2010 vary slightly, both groups determined that Alzheimer’s-related mortality rates were several times higher than the official figure.

In one study, the researchers combined data from the Chicago Health and Aging Project (CHAP) with U.S. census data to estimate the number of deaths of older Americans with Alzheimer’s (Weuve et al., 2014). In a random sample of 1,913 CHAP participants age 65 and older, 990 people died over the course of 6 years. Data from this sample were used to calculate national Alzheimer’s mortality rates.

These findings, reported in the March 2014 issue of Alzheimer’s and Dementia, showed that an estimated 600,000 people age 65 and older with Alzheimer’s died in 2010. The researchers estimate that this number will rise to 900,000 in 2030 and to 1.6 million by 2050. This is an increase from 32 percent of deaths in people age 65 and older attributed to Alzheimer’s in 2010 to an estimated 43 percent in this population in 2050.

The second study, published online on March 5, 2014, in Neurology, found that the number of deaths due to Alzheimer’s disease in people 75 and older could be six times higher than the official count (James et al., 2014). Researchers’ estimate of 503,400 deaths due to Alzheimer’s in 2010 among people in that age group would have made the disease the third leading cause of death in 2010, behind heart disease and cancer.

Researchers followed 2,566 participants in the ongoing Religious Orders Study and the Rush Memory and Aging Study for 8 years. All participants, age 65 and older, were cognitively normal when they entered the studies. Over the course of the research, 22 percent of the volunteers developed Alzheimer’s dementia. About 72 percent of the people with Alzheimer’s disease died during that timeframe, compared with 34 percent of those who remained symptom-free. Based on autopsy findings, the researchers concluded that death certificates do not reflect the large number of Alzheimer’s-related deaths.