The emergence of extremely old people: the case of Japan.

It is acknowledged today that the number of oldest old persons, nonagenarians and centenarians, is increasing rapidly. Analysis of data from Japan, where female life expectancy at birth approaches the assumed limit of 85 years, can provide unique information on whether the rate of these demographic changes is accelerating. Adjusted for the size of the birth cohorts, the centenarian doubling time (CDT i.e. the number of years needed to double the number of centenarians), halved in 29 years. Moreover death rates at 100 years and above show a clear decrease if we exclude males at age 105 and over.