PRB article on measuring population aging features researchers from Demography and Economics of Aging Centers at USC/UCLA and the University of Washington
Which country has the oldest population depends on how you measure 'old.' Eileen M. Crimmins of the University of Southern California finds biological evidence that Americans appear to be aging more slowly than they were two decades ago. Decelerating aging and postponing age-related disease and disability can improve individual quality of life and have profound economic implications.
However, a University of Washington study finds that a 30-year gap separates countries with the highest and lowest ages at which people experience the health problems of an average 65-year-old, reports Nicholas Kassebaum, Joseph Dieleman, and colleagues.