While the study authors can’t say that it was the laid-off autoworkers, specifically, who died of overdoses, the findings gave the researchers the sense that declining economic opportunities are a big part of what drove the opioid epidemic. After all, there are a number of potential connections between joblessness and addiction, says Atheendar S. Venkataramani, an assistant professor of health policy at the University of Pennsylvania and the lead author of the study. Losing a job might mean losing access to health insurance. It could lead to isolation and loneliness, or a sense that there’s little left to live for. “If you feel like the American dream is no longer accessible,” Venkataramani says, “then one may also feel that, Well, it’s not really worth investing in myself ... because investing in yourself is one way to access the fruits of the American dream.”

Venkataramani’s study can be read as yet another sign that Americans are dying “deaths of despair”—that the reason the life expectancies of poor Americans are stagnating or declining is that their dwindling economic opportunities spur them toward drugs, alcohol, and suicide. Many other studies have also found connections between different types of job loss and different types of drug abuse. One 2017 paper, which I wrote about at the time, found that with each percentage-point increase in the unemployment rate, the death rate from opioids rises by 3.6 percent. Another found that economic downturns that lower housing prices, such as the Great Recession, are associated with more opioid-related deaths. A meta-analysis published in the International Journal of Drug Policy examined 28 studies published from 1990 to 2015 in 12 different countries and found that both economic recessions and individual unemployment increases illegal drug use of various kinds. And late last year, another paper found that a rise in manufacturing-related job loss corresponded with an increase in opioid-related deaths.

The authors of these studies tend to speculate that as people lose their jobs, they grow depressed, and they turn to opioids to cope. Opioids can, for some people, provide a soothing, antidepressive effect in addition to pain relief.

A social problem that has, since 1999, killed more than 700,000 Americans—about the population of Boston—has more than one cause. Rich people die from opioids, and so do college kids. In fact, these unemployment studies are tempting precisely because they provide an easy explanation for why so many people became opioid addicts all at once. Job loss is terrible—of course it could make you do something terrible. It’s harder to explain addiction that strikes you down in your prime.

Read: Physicians get addicted too

In fact, some researchers say widespread job loss is far from the only—or even the main—force that inflamed the opioid epidemic. That argument, they say, might let Big Pharma off the hook too easily.