TUESDAY, April 6, 2004 (HealthDayNews) -- While it's long been known that Alzheimer's greatly reduces quality of life, a new study confirms that the disease also decreases the duration of life.
The researchers found the average survival after a diagnosis of Alzheimer's disease was 5.7 years for women and 4.2 years for men.
The study, which appears in the April 6 issue of Annals of Internal Medicine, also found that certain symptoms of the disease, such as problems walking and urinary incontinence, indicated a shorter life expectancy.
"People often wonder what the future will portend and make their plans based on how long they think they'll live," said study author Dr. Eric Larson, director of the Center for Health Studies at Group Health Cooperative in Seattle.
The study's finding that people with Alzheimer's disease have a shorter life expectancy is "something people can intuitively understand," he added.
This information, he said, may help people make plans for the long-term care of a loved one with Alzheimer's. The data may also be useful for refining public health policies and allocating limited health-care resources.
Approximately 4.5 million people in the United States have Alzheimer's disease, according to the Alzheimer's Association.
Larson and his colleagues gathered data on 521 people diagnosed with Alzheimer's disease between 1987 and 1996. All were from the Seattle area, and their ages ranged from mid-60's to late 80s.
The researchers collected information on other existing diseases (heart disease, high blood pressure, diabetes, stroke and depression); education; age; and Alzheimer's symptoms, including falls, wandering, paranoia and urinary incontinence. They also performed a "Mini-Mental State Examination" on each person.
They found that people with Alzheimer's have only about half the average life expectancy at the time they're diagnosed with the disease than people in the general population.
For instance, an American woman who lives to be 70 years old can normally expect to live another 15.7 years. But the study found a 70-year-old woman with Alzheimer's will only live another eight years.
And a 70-year-old American man typically lives another 9.3 more years, but a 70-year-old male with Alzheimer's will only live another 4.4 years, according to the study.
Not surprisingly, the older someone was at the time of the Alzheimer's diagnosis, the shorter the life expectancy was.
The presence of other medical conditions and more severe Alzheimer's symptoms indicated the likelihood of a shorter life expectancy.
"Certain people with Alzheimer's disease have a worse prognosis than others," said Larson. In particular, he said, people with heart disease, diabetes, poor cognitive function, wandering and walking problems don't do well.
He said the shorter life expectancy may not be directly related to Alzheimer's, but the disease may cause indirect consequences that decrease longevity. For example, people with Alzheimer's are less active, which may predispose them to heart disease or pneumonia. And they're less adaptable, which may make them more prone to falls and injuries, Larson said.
Katie Maslow, associate director for Quality Care Advocacy for the Alzheimer's Association, added, "For a family, while it's difficult to hear, it's good to understand what the likelihood of survival is when planning for the care of a person. And this information is particularly valuable for letting physicians know what factors influence how long a person might live."
Maslow noted that it was discouraging to see that about half the people in this study already had significant cognitive loss when they were diagnosed.
She pointed out that there are medications that may help if the disease is diagnosed earlier. And existing diseases, such as heart disease and diabetes, can be managed more effectively if family members know that dementia is present, she said.
Dr. Barry Reisberg, clinical director of the Silberstein Aging and Dementia Research Center in New York City, said this study "provides newer and additional information" on the Alzheimer's disease process.
It's important for people to realize that "patients with proper care need not suffer, and that caregivers with proper support can better cope with this condition," he added.
Knowing how long a person might live, he noted, could help families plan so they can be sure proper support is available.