TWO DATA points, it is often said, do not make a trend. Researchers studying America’s dismal life expectancy now have three. After climbing gradually over the past half century, life expectancy in America reached a plateau in 2010 and then fell for three consecutive years from 2015 to 2017, the latest for which data are available. An American baby born today can expect to live 78.6 years, on average, down from 78.9 in 2014. A new paper by researchers at Virginia Commonwealth University, published in the Journal of the American Medical Association, attempts to explain why.

The prevailing wisdom is that rising mortality in America can be blamed in large part on a handful of causes, including drug overdoses, alcohol-related illnesses and suicides. Such “deaths of despair”, the argument goes, are concentrated mainly among whites living in economically depressed regions. Indeed the authors of the paper estimate that mortality from drug overdoses among adults aged 25 to 64 increased by 386.5% between 1999 and 2017. Deaths from alcoholic liver disease jumped by 40.6% during this period, while suicides rose by 38.3%. But the authors note that mortality has increased across 35 causes of death, suggesting that the problem is systemic. Moreover, all racial and ethnic groups have been affected.

Some groups have been affected more than others, however. Young people have been hit especially hard. Between 2010 and 2017, the mortality rate increased by 6% among all working-age adults (from 328.5 to 348.2 deaths per 100,000 population). Among those aged 25 to 34, it jumped by 29% (from 102.9 to 132.8). Adults with less education have also experienced a big rise in mortality. Geography provides another clue. Of the 33,000 “excess deaths” that occurred in America between 2010 and 2017—defined as the deaths attributed to the change in the mortality rate each year—a third happened in Ohio, Pennsylvania, Indiana and Kentucky, even though those four states are home to just a tenth of the national population.

Such regional disparities suggest that not all Americans are doomed to live shorter lives. Indeed life expectancies in the country’s most populous states (California, Texas, and New York) have changed little since 2010. In coastal areas, they have improved at roughly the same rate as in Canada. Still, many of the underlying causes of higher mortality in America, such as economic distress, are likely to persist. The current trend in Americans’ life expectancy may continue for many data points to come.