April 4, 2004
How long can patients with Alzheimer's disease survive?
Researchers from Group Health and UW identify predictors
Seattle—How long can a patient newly diagnosed with Alzheimer's disease (AD) expect to live? This important question has been difficult to answer for patients, families, and health professionals planning care of this irreversible brain disorder. But a new study from Group Health Center for Health Studies and the University of Washington suggests that assessing several key clinical aspects of the disease soon after diagnosis can help.
The study, published in the April 6 issue of the journal Annals of Internal Medicine, included these key findings:
- People newly diagnosed with AD survived about half as long as those of similar age in the U.S. For instance, median survival was 8 years for women aged 70 diagnosed with AD, compared to 15.7 years for similarly aged American women who do not have the disease. Similar trends were found among 70-year old men with AD. They had a median survival time of 4.4 years compared with 9.3 years for men without the disease in the U.S. population.
- Women with AD tended to live longer than men, surviving an average of 6 years compared to men—who lived for an average of about 4 years after diagnosis. But this gender gap narrowed with age.
- Age at diagnosis was also a factor. Those who were diagnosed with AD in their 70s had longer survival times than those diagnosed at age 85 or older.
- Severity of AD and other medical conditions were stronger predictors of length of survival than social factors such as race or education.
"We've always known that Alzheimer's disease shortens patients' lives, but there have been few long-term studies that relate patient age and symptoms to length of survival," said Eric B. Larson, MD, MPH, director of the Group Health Center for Health Studies and principal investigator of the study, which was supported by the National Institute on Aging (NIA). Larson is the former medical director at the University of Washington Medical Center, where he and his colleagues began this line of research in 1987.
To conduct the study, Larson's team recruited 521 study participants from a population base of 23,000 people living in the Seattle Area, who were then added to an Alzheimer's disease patient registry. All 521 were Group Health Cooperative members aged 60 and older who had been recently diagnosed with Alzheimer's disease.
"One strength of the study is that it examined the experience of newly diagnosed patients just as they are typically found in everyday outpatient settings," said Larson. "Previous studies have relied on populations of more severe cases, such as those in nursing homes."
As patients entered the study, each person was evaluated for cognitive and memory problems and examined for other conditions including heart disease, heart failure, diabetes, stroke, depression, and urinary incontinence. They were also assessed for a history of agitation, wandering, paranoia, falls, and walking difficulties. Survival was measured from the time of initial diagnosis until death or when the study ended in 2001. The average follow-up period was about five years, with an approximate range from two-and-a-half months to 14 years.
The researchers found that:
- Survival was poorest among those aged 85 and older who wandered, had walking problems, and had histories of diabetes and congestive heart failure.
- The difference in the life expectancy between those who were diagnosed with AD and the general population progressively diminished with age. At 85, for example, median life expectancy for women with AD was 3.9 years after diagnosis compared to about 6 years for women who didn't have the disease. Similarly, 85-year-old men with newly diagnosed AD had a median life expectancy of 3.3 years compared to 4.7 for men of the same age who didn't have AD.
- Poor scores on the initial tests of memory and cognitive performance predicted shorter survival time after diagnosis. In fact, a five-point drop in one key test, the Mini-Mental State Exam, during the first year following diagnosis predicted up to a 66 percent increase in death after that initial year.
- Walking problems, congestive heart failure, and a history of falls, diabetes, and heart attacks were other important predictors of reduced life expectancy after AD diagnosis.
"Research that sheds light on the course of Alzheimer's disease is so important for physicians, patients, and families," said Neil Buckholtz, PhD, chief of the Dementias and Aging Branch at the NIA. "Having an idea of what to expect can hopefully be of some benefit in planning for what lies ahead."
The findings may also help public health officials refine cost projections and plan services for the growing number of older Americans at risk for AD, Larson says.
AD is an irreversible disorder of the brain that causes loss of memory and eventually overall mental and physical function, leading to death. It is the most common cause of dementia among people over age 65. Recent studies estimate that up to 4.5 million people currently have the disease, and the prevalence (the number of people with the disease at any one time) doubles every 5 years after the age of 65.
Other researchers who contributed to the study were the University of Washington's Marie-Florence Shadlen, MD; Li Wang, MS; Wayne C. McCormick, MD, MPH; James D. Bowen, MD; Linda Teri, PhD; and Walter A. Kukull, PhD.
Group Health Center for Health Studies
Group Health Research Institute does practical research that helps people like you and your family stay healthy. The Institute is the research arm of Seattle-based Group Health Cooperative, a consumer-governed, nonprofit health care system. Founded in 1947, Group Health Cooperative coordinates health care and coverage. Group Health Research Institute changed its name from Group Health Center for Health Studies in 2009. Since 1983, the Institute has conducted nonproprietary public-interest research on preventing, diagnosing, and treating major health problems. Government and private research grants provide its main funding.