Over the past 15 years, the death rate for middle-aged white Americans has gone up, an effect public health experts have largely attributed to the ongoing U.S. opioid epidemic. However, a new analysis out of Princeton University suggests the recent increase in drug-related mortality may be a symptom of a much greater issue in this country, namely, how society seems to have left behind its working class, The Washington Post reports

The analysis is a follow-up to a 2015 study in which Princeton economists Anne Case and Angus Deaton highlighted three “diseases of despair”—drugs, drinking and suicide—that were leading to an increase in mortality among white people in the United States. Specifically, the report found that death rates from drug and alcohol poisonings, suicide, chronic liver disease and cirrhosis accounted for much of the increase in mortality.

However, this latest update suggests the problem of dying whites can’t be explained simply by the drug epidemic alone. “Ultimately, we see our story as about the collapse of the white, high school educated working class after its heyday in the 1970s and the pathologies that accompany that decline,” study authors wrote. 

For instance, the report shows that 15 years ago, middle-aged white Americans were tied with middle-aged Germans with regard to longevity. Now, they are 45 percent more likely to die than their foreign counterparts. Study authors found that the recent spike in drug use, drinking and suicides could explain 32 percent of the additional deaths among 45- to 54-year-olds in the United States. But what of the remaining nearly 70 percent? 

In the paper, Case and Deaton say heart disease is part of the problem, since cardiovascular issues are a top killer for white middle-aged people living in the United States. The report’s economic data also suggest income could be to blame, since most of the increase in white deaths appears to be concentrated among those who never finished college. However, take that with a grain of salt, since study authors also noted that the death rate among less-educated Black Americans over the last decade and a half has significantly decreased in the U.S. (despite the fact that their white counterparts still earn 36 percent more in the same jobs).

Ultimately, the analysis’s main theory comes back to despair. Case and Deaton believe that white Americans may be suffering a loss of hope, which is fueling both physical and mental health issues. If they’re right, solving the issue of increased white mortality will be much harder to solve than simply passing laws to keep opioids out of peoples’ hands or doling out hepatitis C virus (HCV) treatment.