While most Americans enjoy longer and healthier years of living, youth continues to struggle with anxiety and fitness, according to a paper co-written by professor of applied economics David M. Cutler ’87.

Using collected government-issued surveys and national morality data, researchers found improvements in the length and quality of life for the average American after examining trends in quality-adjusted life expectancy from 1987 to 2008. The findings were published last Thursday in the American Journal of Public Health.

“I think that the innovation of this study is that we worked with a lot of national data sources to really try to bring information together about as much of the population as we could,” said Allison B. Rosen, a professor at the University of Massachusetts Medical School who co-wrote the paper. “We found that health has improved. Both life-expectancy has improved and the quality of life in those extra years has improved.”

Improvements in health, however, were not the same among all age groups. While anxiety declined significantly during the 2000s for the elderly, young adults—those around 25 years of age—did not exhibit a similar decrease.

“In our minds that’s an important trend to notice, but we haven’t gotten to a point where we can say what’s causing that yet,” Rosen said. “We haven’t seen similar increases of anxiety among the elderly, so it’s definitely something that’s occurring in the younger generation.”

Youth also showed impairments in physical fitness. Co-writer Susan Stewart, a researcher at the National Bureau of Economic Research, cited walking as one of the main problems faced by youth.

“We think it’s probably related to sedentary lifestyle and fitness, but these are speculative,” Stewart said.

S. Jay Olshansky, a professor at the University of Illinois at Chicago, remarked on the study’s innovative methodology, adding that the study “makes a valuable contribution to the literature by providing a level of detail in the analysis of life-expectancy that has not been done before.”

“I think a lot of people think when they see this study, it is a message that health is getting better in the nation,” Rosen said. “While that can be one message, I think the most important message is that we are actually capable of using existing national data of measuring the health of the nation and tracking it over time.”

This article has been revised to reflect the following correction:

CORRECTION: Sept. 20, 2013

An earlier version of this article incorrectly named a fourth co-author on a recent paper on lifespan, anxiety, and fitness written by three researchers. In fact, the paper was not written by Otto Eckstein, who was a Harvard economics professor for several decades in the latter half of the 20th century. The article also misquoted co-author and National Bureau of Economic Research researcher Susan Stewart. In fact, Stewart said that walking problems among youth are likely related to “sedentary,” not “sanitary,” lifestyle and fitness.