Life expectancy in the United States has dropped for the second time in two years due to a large rise in young deaths from drug overdoses, new figures show.
Average life expectancy in the US in 2016 was 78.6 years, a decrease of 0.1 year from 2015, when it dropped 0.1 year from 2014's 78.8 years, according to the Centers for Disease Control and Prevention (CDC).
It has also released drug overdose death statistics which reveal 21% more people died in 2016 than in 2015, with a total of 63,600 drug overdose deaths in the US last year.
Drug overdose deaths involving synthetic opioids other than methadone, such as fentanyl and tramadol, doubled between 2015 and 2016 from 3.1 to 6.2 per 100,000.
Multiple years of decline in life expectancy are usually associated with AIDS epidemics in Africa or wars in Syria and Afghanistan, Maji Ezzati, professor of public health at Imperial College London said.
"The story does come down to young people. It's the overdose story, to a large extent," he told the Washington Post.
The last time the United States experienced two years of declining life expectancy was in 1962 and 1963 because of an influenza epidemic.
In 1993 the figure dropped for a year due to the AIDS epidemic.
Of the 63,600 drug overdose deaths last year, more than 42,000 were due to opioids.
Of those opioid deaths 19,413 people died from synthetic opioids, up from 9,580 in 2015.
President Donald Trump declared in October the US opioid crisis was a "national public health emergency".
Keith Humphreys, an addiction specialist at Stanford University said the figures are "even worse than it looks" as research has shown the actual number of opioid deaths could be 20% higher.
In 2016 the number of deaths in younger people, aged 15 to 44, rose while those aged 75-84 declined.
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In correlation with 2016's life expectancy numbers, adults aged 25-54 had the most amount of drug overdose deaths.
The number of deaths from all drug overdoses has increased more than three times the rate in 1999.