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In developed countries, the increasing number of elderly people will be the trend to watch. In developing ones, though, there could be an important impact from a growing working-age population.

People are living longer and having fewer children, but the impact of this differs among nations. This difference is linked to the state of health, as well as age-structure profiles, in developed and developing nations.

In developed countries such as the United States, vaccinations, antibiotics, and improved sanitation long ago reduced high infant and child death rates. People over 60 years of age account for three-quarters of all deaths in these nations. Treatment of adult conditions, especially chronic diseases, will have the most impact in reducing mortality.

In low-income, developing nations, the child death rate remains high. Infants and children up to age 4 account for nearly a third of all deaths, compared with only about 1 percent in developed nations. Measures to prevent or treat childhood infectious diseases will have the greatest impact in reducing overall mortality in these nations.

U.S. Heart Disease Deaths to Rise More Rapidly Than Cancer Deaths

The leading cause of death in the United States is heart disease, followed by cancer, according to the Centers for Disease Control and Prevention. The risk of dying from heart disease rises sharply after age 65, and the risk of cancer rises more slowly.

Thus, deaths from heart disease are predicted to rise more rapidly than those from cancer in coming years, partly because of population aging. The national heart disease rate had been declining for 40 years, but recently leveled off.

Unless risk factors such as obesity are reduced, those deaths are predicted to nearly triple from 2000 to 2050, from 740,000 to 2.1 million. Cancer deaths are forecast to slightly more than double during that same time period, from 560,000 to nearly 1.3 million.

Developing Countries Could Have a Temporary Demographic Bonus

In developing nations, steps to address high infant and child death rates will ripple upward through the population in coming decades. At first, there will be a baby boom. Eventually, as more children survive, people will have fewer children.

For a time, there could be more people in their working years in these countries than children or the elderly. This predicted change, by increasing the size of the labor force, would create the potential for economic growth that is sometimes called the “demographic dividend.”

Under this scenario, healthier children would eventually become healthier workers. School attendance would improve, creating higher education levels and an incentive to invest in education. People would live longer, so would have more time to save money over their lifetimes. This creates a “virtuous circle” in which higher income feeds health improvements and vice versa.

But this dividend is not automatic, warn economists David Bloom and David Canning. If businesses are not given policy incentives to use this new labor, high unemployment and rising crime rates could result. Their prescriptions include openness to international trade, flexible labor laws, and incentives for businesses to invest.

Long-Term Impact of Chronic Diseases

A major shift in the pattern of causes and transmissions of diseases, due in part to the aging of the population, means that chronic diseases are predicted to cause more illness and death than infectious and parasitic diseases in coming decades. As more people survive into adulthood and old age, unhealthy habits such as smoking and environmental factors such as pollution will catch up with them and contribute to chronic conditions.

One question for the future is whether chronic conditions such as diabetes, cancer, and heart disease will progress into disability. The prognosis is mixed. In some developed nations, such as the United States, Denmark, Finland, Italy and the Netherlands, longevity has increased and disability levels have dropped. Disability rates have remained stable as the population has aged in Australia, Canada and France. Severe disability rates have risen in Belgium, Japan, and Sweden.

D’Vera Cohn is senior editor at the Population Reference Bureau.

Marlene Lee is a senior policy analyst at the Population Reference Bureau.

Funding for this article was provided by the National Institute on Aging.