Aug. 18, 2008 -- If you make it to your 92nd birthday, your odds of staying spry as you head toward the century mark may be better than you expect.

That news comes from a study of 2,262 Danish adults starting at age 92. Everyone born in 1905 in Denmark and still living there was invited to participate, whether they lived at home or in an institution and needed someone to help them take part in the study. They were followed until they reached 100.

The study was all about seeing whether exceptional longevity came with high levels of disability. The short answer: It didn't. Extreme age didn't bring extreme disability, overall.

The elders did have a slight decline in their ability to perform routine activities, mental skills test scores, grip strength, and other measures, and fewer were independent at 100 than at 92.

"Nonetheless, our finding also suggests that individuals who survive into the highest ages have a health profile that is similar in many aspects to that of individuals who are seven or eight years younger," write the researchers, who included Kaare Christensen, MD, PhD, DMSc, of the Danish Aging Research Center at the University of Southern Denmark.

It's not that no one got sick, slowed down, or died -- only 166 people were still enrolled in the study at age 100. It's more that they didn't linger in what the researchers call a "frail... vegetative state."

"Even though individuals in this age range have an increased risk of disability for each additional year of life, the frailest and most disabled members of the cohort are those who are most likely to die at any given age," explain Christensen and colleagues.

Their bottom line: "Most individuals can expect to experience physical decline before they die, but the postponement of this individual decline makes it possible for us to live into a fourth age" stretching toward 100.

The study appears in this week's online early edition of Proceedings of the National Academy of Sciences.