“Men and women with a high school degree or less are being hammered here,” she said. Patients are reporting higher levels of pain than they used to, and those who do also show greater social isolation.

What’s confounding researchers is that this is a uniquely American phenomenon. Europe’s economic woes haven’t had the same impact on life expectancy.

One result of diverging mortality is that wealthier Americans are reaping a greater share of the Social Security pie since they can afford to retire later, get larger checks and enjoy the program’s benefits further into their golden years. Poorer Americans have to tap it earlier, get smaller checks and don’t live as long to reap its benefits.

“They, unlike their more affluent compatriots, are not sharing in the gains in life expectancy,” said Gary Burtless, a senior fellow at Brookings. That should push the U.S. to weigh changes that would better preserve benefits for lower earners.