A couple of weeks ago President Obama mocked Republicans who are “down on America,” and reinforced his message by doing a pretty good Grumpy Cat impression. He had a point: With job growth at rates not seen since the 1990s, with the percentage of Americans covered by health insurance hitting record highs, the doom-and-gloom predictions of his political enemies look ever more at odds with reality.

Yet there is a darkness spreading over part of our society. And we don’t really understand why.

There has been a lot of comment, and rightly so, over a new paper by the economists Angus Deaton (who just won a Nobel) and Anne Case, showing that mortality among middle-aged white Americans has been rising since 1999. This deterioration took place while death rates were falling steadily both in other countries and among other groups in our own nation.

Even more striking are the proximate causes of rising mortality. Basically, white Americans are, in increasing numbers, killing themselves, directly or indirectly. Suicide is way up, and so are deaths from drug poisoning and the chronic liver disease that excessive drinking can cause. We’ve seen this kind of thing in other times and places – for example, in the plunging life expectancy that afflicted Russia after the fall of Communism. But it’s a shock to see it, even in an attenuated form, in America.

Yet the Deaton-Case findings fit into a well-established pattern. There have been a number of studies showing that life expectancy for less-educated whites is falling across much of the nation. Rising suicides and overuse of opioids are known problems. And while popular culture may focus more on meth than on prescription painkillers or good old alcohol, it’s not really news that there’s a drug problem in the heartland.