THURSDAY, Jan. 30, 2020 (HealthDay News) -- After four years of declines, life expectancy in the United States increased in 2018, health officials reported Thursday.

The jump in longevity comes as deaths from opioid overdoses dropped for the first time in 28 years, as did deaths from six of the 10 leading causes.

The new data could be a glimmer of good news for Americans' health, with recent declines in average lifespans initially casting doubt on progress made over the past decades.

"The three-year trend in life expectancy for the total population either decreasing or remaining steady has stopped, with the increase in life expectancy in 2018," said lead researcher Kenneth Kochanek, from the U.S. Centers for Disease Control and Prevention's National Center for Health Statistics (NCHS).

"The decrease in mortality from unintentional injuries in 2018 is a reverse from the 2014-to-2017 trend," he added.

"From 2014 to 2017, the increase in deaths from unintentional injuries contributed the most to the decrease in life expectancy, with decreases in cancer mortality offsetting this change in life expectancy," Kochanek said.

Between 2010 and 2014, life expectancy increased from 78.7 years to 78.9 years, then fell between 2014 and 2017 from 78.9 years to 78.6 years.

But in 2018, it went back to 78.7 years, which is still below the peak of 78.9 years in 2014, Kochanek said.

The 10 leading causes of death in the United States are heart disease, stroke, chronic respiratory disease, Alzheimer's disease, diabetes, flu, kidney disease, suicide, cancer and accidents.

Between 2017 and 2018, decreases in deaths from cancer and unintentional injuries contributed the most to the increase in life expectancy, with increases in mortality from influenza and pneumonia offsetting the change in life expectancy, Kochanek added.

According to Dr. Howard Koh, a professor at Harvard T.H. Chan School of Public Health in Boston, "After years of plateauing and declining U.S. life expectancy, this one-year uptick is certainly welcome news."

But more detailed evaluation over time is needed to judge whether declining trends are truly being reversed, he said.

Another expert agreed that the increase in life expectancy was welcome news, but must be taken with a grain of salt.

"It's good news U.S. life expectancy increased for one year, interrupting its fall over the past three years, but the overall picture remains bleak," said Dr. Steven Woolf, director emeritus and senior advisor at the Center on Society and Health at Virginia Commonwealth University School of Medicine, in Richmond.

For many years, life expectancy in other wealthy nations has been higher than in the United States, and their life expectancy rates have been climbing, Woolf said.

The increase in life expectancy between 2017 and 2018 is statistically significant, but time will tell whether it holds, he added. A similar increase occurred between 2013 and 2014 before falling the following year.

Other findings in the report include:

• Among the 10 leading causes of death, only deaths from suicide and flu-related pneumonia rose.
• More than half the increase in life expectancy in 2018 was from fewer deaths from cancer and accidents.
• Drug overdose deaths dropped 4% from 2017 to 2018, from about 70,200 in 2017 to nearly 67,400 in 2018. The majority of drug overdose deaths (90%) were unintentional.
• Drug overdose deaths in 2018 dropped in 14 states and the District of Columbia. Across the country, the overdose death rate was 20.7 per 100,000 in 2018 and 21.7 in 2017.
• The rate of drug overdose deaths from drugs such as fentanyl, fentanyl analogs and tramadol rose 10% from 2017 to 2018.
• Between 2012 and 2018, the rate of drug overdose deaths from cocaine more than tripled, and from drugs such as methamphetamine increased five times.

Koh pointed out that, "while the overall decline in drug overdose deaths is notable and must continue, rising mortality from synthetic opioids -- as well as from cocaine and methamphetamine -- represent the next disturbing wave of the nation's ongoing substance use challenge."

Woolf added that it's good news that the rate of fatal drug overdoses has decreased.

"But this, too, should be put in perspective," he said. "It's still higher than it was in 2016 and alarmingly higher than it's been in the past two decades."

The report was published Jan. 30 in the CDC's NCHS Data Brief.

More information

For more on life expectancy, head to the CDC's National Center for Health Statistics.