“I think we should be very concerned,” said Princeton economist Anne Case, who called for thorough research on the increase in deaths from heart disease, the No. 1 killer in the United States. “This is singular. This doesn’t happen.”

A year ago, research by Case and Angus Deaton, also an economist at Princeton, brought worldwide attention to the unexpected jump in mortality rates among white middle-aged Americans. That trend was blamed on what are sometimes called diseases of despair: overdoses, alcoholism and suicide. The new report raises the possibility that major illnesses may be eroding prospects for an even wider group of Americans.

Its findings show increases in “virtually every cause of death. It’s all ages,” said David Weir, director of the health and retirement study at the Institute for Social Research at the University of Michigan. Over the past five years, he noted, improvements in death rates were among the smallest of the past four decades. “There’s this just across-the-board [phenomenon] of not doing very well in the United States.”