Alzheimer's shortens the average lifespan of persons diagnosed at a relatively young age by a greater percentage than those diagnosed late in life, according to researchers at Johns Hopkins University in Baltimore, Maryland.

Investigators conducted a study to determine the effect of Alzheimer's disease on a patient's life span. Study participants were from the Baltimore Longitudinal Study of Aging and were all over age 55.

The average survival times ranged from 8.3 years for those diagnosed with Alzheimer's disease at age 65 years to 3.4 years for persons diagnosed with Alzheimer's disease at age 90 years.

Diagnoses of Alzheimer's disease at ages 65 and 90 years were associated with approximately a 67 percent and 39 percent reduction in average life span, respectively.

There were no significant differences between men and women in survival after receiving a diagnosis of Alzheimer's disease, according to the report in the Archives of Neurology.

Caregivers, patients and their families could plan on an average life span as long as seven to ten years for patients whose conditions are diagnosed when they are in their 60s and early 70s, to only about three years or less for patients whose conditions are diagnosed when they are in their 90s, according to the researchers.

Other sources: Archives of Neurology