The life expectancy of Americans has not kept pace with that of other wealthy countries and is now decreasing.

According to a study published Tuesday in the Journal of the American Medical Association, drug overdose, suicide, and alcohol abuse were among the reasons why life expectancy was shortening for Americans.

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Adults ages 25-64 of all racial groups have seen an increase of 6% in mortality rates, which is the largest increase among groups studied. The largest increase has been in the Ohio Valley and New England.

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The United States had been making steady progress, with life expectancy increasing to 78-years-old over the last half-century, but the pace slowed over time and began to decline in 2014 and has continued to decline in the three years that followed.

“The implications for public health and the economy are substantial, making it vital to understand the underlying causes,” the researchers said.

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The researchers found that other high-income countries continue to see a steady rise in life expectancy.