Dec. 8, 2016 -- Life expectancy for Americans declined last year, the first time that's happened in more than two decades, according to a National Center for Health Statistics report released Thursday.
It said the decrease was due to rising rates of death for eight of the top 10 leading causes of death, including heart disease and stroke, diabetes, drug overdoses, and accidents, the Washington Post reported.
Life expectancy in the U.S. fell from 78.9 in 2014 to 78.8 in 2015. The last decline was in 1993, when it decreased from 75.6 to 75.4.
The overall death rate rose 1.2 percent last year, the first increase since 1999. In 2015, more than 2.7 million people died, and about 45 percent of those deaths were due to heart disease or cancer, the Post reported.
"This is unusual, and we don't know what happened," report lead author and epidemiologist Jiaquan Xu said. "So many leading causes of death increased."
Some experts say the findings are cause for concern.
The report shows increases in "virtually every cause of death. It's all ages," David Weir, director of the health and retirement study, Institute for Social Research, University of Michigan, told the Post.
He pointed out that over the past five years, improvements in death rates were among the smallest of the past four decades. "There's this just across-the-board [phenomenon] of not doing very well in the United States," Weir said.
However, other experts advised against interpreting too much from one year of data, saying there could be a reversal next year, the Post reported.