December 17, 2008
People with Alzheimer's disease who also have diabetes or high blood pressure are more likely to die sooner than people without such disorders. The impact of these diseases may be especially pronounced in Whites who are diagnosed with Alzheimer's, compared to Blacks or Hispanics with the disease. The findings appeared in Neurology, the medical journal of the American Academy of Neurology.
Earlier studies have shown that people with Alzheimer's disease tend to live, on average, from three to nine years after they are diagnosed with the disease. But there is wide individual variation, with some patients living for 10 years or longer. Coexisting diseases in elderly patients, including diabetes and heart disease, can complicate the picture, since some people may die of ailments other than Alzheimer's disease.
In the current study, researchers followed 323 people who had no memory problems when first tested but later developed dementia. Their average age was 83 at the time they were diagnosed with Alzheimer's disease.
The study found that after an Alzheimer's diagnosis was made, people with diabetes were twice as likely to die sooner than those without diabetes who had Alzheimer's disease. People with Alzheimer's disease who had high blood pressure were two-and-a-half times more like to die sooner than those with normal blood pressure.
"Here we have two controllable factors that may drastically affect how long a person with Alzheimer's can survive," said study author Yaakov Stern, Ph.D., of Columbia University Medical Center in New York.
The study also looked at how race could affect how long a person lives with Alzheimer's disease. Although some trends were noted, it could not be determined whether race affects the survival of people living with Alzheimer's. However, it is possible that socioeconomic factors like income and education may cause differences in survival.
Other studies have shown that Hispanics and Blacks tend to live longer after a diagnosis of Alzheimer's. This may be due, in part, to an earlier age at diagnosis for minority groups in the United States. [See the ALZinfo.org story, "Alzheimer's May Hit Minorities Especially Hard,"] For example, one earlier study found that, on average, Hispanics began to show symptoms of Alzheimer's nearly seven years earlier than their White counterparts. Another reported that middle-aged blacks are much more likely to suffer from the disease than whites of the same age.
Studies have also shown various trends relating to Alzheimer's and survival.
Women with Alzheimer's tend to live longer than men.
Overall, women who had Alzheimer's tended to live longer than men with the disease. In one large study, women survived an average of about 6 years after they were diagnosed, versus 4 years for men. However, there is considerable variation from person to person.
Alzheimer's cuts life expectancy.
Americans with Alzheimer's survived about half as long as those of similar age who did not have the disease. A woman who is diagnosed with Alzheimer's at age 70, for instance, would be expected to live on average for about eight more years. The typical 70-year-old woman without the disease, on the other hand, would be expected to live another 16 years. The figures are smaller for American men, who tend to have shorter life expectancies in general: 4.4 years for a 70-year-old man diagnosed with Alzheimer's, versus 9.3 years for a man without the ailment.
The older the age at diagnosis, the shorter the life expectancy.
The older a man or woman is when they were told they have Alzheimer's, the less gap there was in life expectancy between men and women. At age 85, women diagnosed with Alzheimer's have a median life expectancy of almost 4 years, versus 6 years for women who didn't have the illness. Men newly diagnosed at age 85 have a life expectancy of 3.3 years, compared to 4.7 years for those without Alzheimer's.
The more severe the symptoms at the time of diagnosis, the shorter the survival.
Someone who has more severe symptoms when they are told they have Alzheimer's would not be expected to live as long as someone who has milder disease. Important predictors of diminished life expectancy include behaviors like wandering, falls, or a history of diabetes or heart disease.
E.P. Helzner, Ph.D.; N. Scameas, M.D.; S. Cosentine, Ph.D., et al: "Survival in Alzheimer's Disease: A Multiethnic, Population-Based Study of Incident Cases." Neurology, Volume 71, November 5, 2008, pages 1489-1495.