India,China account for one-third of world's ageing population

"The 65-and-older population in China and India alone numbered 166 million in 2008, nearly one-third of the world's total," said the report "An Aging World: 2008" of the US' NIA.

"Issues related to population aging in the world's two most populous nations will be accentuated in the coming decades as the absolute number climbs to 551 million in 2040 (329 million in China and 222 million in India)," it said.

Director of NIA's Division of Behavioral and Social Research Richard Suzman said for the first time in human history, within 10 years, there will be more people above 65 years of age and older than children under five in the world.

According to the report, while developed nations have relatively high proportions of people above 65 years of age and older, the most rapid increases in the older population are in the developing world.

The current rate of growth of the older population in developing countries is more than double that in developed countries, and is also double that of the total world population. "As of 2008, 62 percent (313 million) of the world's people were 65 years of life and older lived in developing countries. By 2040, today's developing countries are likely to be home to more than 1 billion people 65 and over, 76 percent of the projected world total," the NIA report said.

It said the oldest of the old, people above 80 years of age and older, are the fastest growing portion of the total population in many countries.

Globally, the oldest old population is projected to increase 233 percent between 2008 and 2040, compared with 160 percent for the population 65 and over and 33 percent for the total population of all ages.

"The world's population of people over age 65 is growing rapidly, and with it will come a number of challenges and opportunities," said NIA Director Richard J Hodes.

"NIA and our partners at the Census Bureau are committed to providing the best data possible so that we can better understand the course of population ageing and its implications," he said.

Suzman said: "Ageing is affecting every country in every part of the world."

"While there are important differences between developed and developing countries, global ageing is changing the social and economic nature of the planet and presenting difficult challenges."

"The fact that, within 10 years, for the first time in human history there will be more people 65 and older than children under five in the world underlines the extent of this change," Suzman said.

The report examines nine international population trends identified in 2007 by the NIA and the US Department of State ("Why Population Aging Matters: A Global Perspective").

The report also contains detailed information on life expectancy, health, disability, gender balance, marital status, living arrangements, education and literacy, labor force participation and retirement and pensions among older people around the world.