An automotive assembly plant closing in a US county has been associated with 85% higher opioid overdose death rates among working-age adults in that county after five years, according to a study published in the medical journal JAMA Internal Medicine on Monday.

“Relative to the trends in manufacturing counties where an automotive plant did not close, having a plant closure meant that your opioid overdose death rate was 85% higher after five years than it otherwise would have been — and that was a large number to us,” said Dr. Atheendar Venkataramani, assistant professor at the University of Pennsylvania Perelman School of Medicine, who was first author of the study.

“The study is important because it shows that when economic opportunities collapse, it not only has consequences for people’s economic wellbeing but it might adversely affect their health too,” Venkataramani said. “Economic opportunity matters for our health, and as the forces that are shifting economic opportunities for people are continuing to evolve, we have to think about how policies can both make people resilient — from a health sense — to the negative changes that might happen, and we also have to think about what types of policies on the economic side may actually give people opportunities, which may also bolster their health.”

The study involved a database of automotive assembly plants in operation as of 1999, which researchers built using data from industry trade publications, automotive company websites and newspaper articles.

The researchers took a close look at the location of each plant and dates of closure. They examined the database at the county level and identified 112 manufacturing counties where the percentages of employed residents working in manufacturing were in the top quintile nationwide. The counties were primarily in the Midwest and the South. Twenty-nine of the 112 counties had closures between 1999 and 2016.

The researchers also examined opioid overdose death rates among adults ages 18 to 65 within those counties, using data from death certificates between 1999 and 2016.

After comparing data, the researchers found that countywide opioid overdose deaths increased in each of the first five years after a plant had closed in a county, and plateaued thereafter.

The data suggested that five years after a plant closure, opioid overdose death rates increased by 8.6 deaths per 100,000 people in a county, representing an 85% increase relative to counties that did not experience closures, according to the study’s findings.

The researchers also found that the magnitude of that association between plant closures and opioid overdose deaths was largest among white men.

The study had some limitations, including that it found only an association between plant closures and opioid overdose death rates, not a causal relationship. More research is needed to unpack the complexities of the association.

In the United States, where it’s estimated that more than 130 people die every day as the result of an opioid overdose, deaths due to drug overdose, alcohol and suicide have been called “deaths of despair” — and those deaths have been largely responsible for rising mortality rates among middle-age white Americans.

The economy and other social factors may be playing roles in those deaths — and these factors may include a shortage of steady jobs for people without a college degree.

“And when the jobs just aren’t there, they sink into depression or that feeling of general hopelessness,” Shannon Monnat, a professor of rural sociology from Penn State University, previously said in 2017. Monnat was not involved in the new study.

Increases in these deaths of despair have been so significant in recent years that they are major drivers in reducing American life expectancy.

A report issued in September by the US Congress Joint Economic Committee titled “Long-Term Trends in Deaths of Despair” noted, “Mortality from deaths of despair far surpasses anything seen in America since the dawn of the 20th century. … The recent increase has primarily been driven by an unprecedented epidemic of drug overdoses.”