Opioid overdose deaths throughout Midwest most strongly linked to a lack of economic upward mobility, Boston College study finds

Chestnut Hill, Mass. (1/23/2025) – The unprecedented increase in drug overdose deaths in the U.S., long believed to be driven by access to legal and illegal opioids, is most closely tied to an equally dramatic decline in upward income mobility, according to a new analysis by Boston College researchers.

Reporting in the International Journal of Drug Policy, the researchers evaluated the possible influence of another major 21st century trend: growing income inequality, said Gene Heyman, a senior lecturer in BC’s Department of Psychology and Neuroscience.

“According to received opinion, the primary driver of opioid overdose deaths was increased access to opioids, particularly legal opioids prescribed for pain,” said Heyman. “But our analysis found the strongest predictor of overdose deaths was whether or not an individual was stuck in lower income brackets.”

The question the researchers set out to answer was, “what was making individuals increasingly susceptible to the lure of intoxicating drugs?”, according to the co-authors, who also included Boston College psychologists Ehri Ryu and Hiram Brownell.

“This had not been as thoroughly investigated as had the role of opioid prescriptions,” said Heyman. “Our analyses synthesized recent research on county-level variation in overdoses, income, education, and family structure. 

Following the lead of economists, the team created an index of growing income inequality centered on the degree to which individuals remained stuck in those lower income brackets, a measure referred to as “intergenerational income mobility.”

Overdose death rates and measures of income inequality vary markedly between states, counties, and even census tracts. An earlier report by the team looked at state-by-state differences. This time, the team examined overdose differences in the 1,056 counties of the 12 Midwest states. 

The team used statistical techniques to quantify the contribution of seven predictors: opioid prescription rates, income mobility, family structure, educational attainment, school class size, employment, and social networks.

“From all those predictors, we found intergenerational income mobility was the strongest predictor of drug overdose deaths each year between 2006 and 2021,” said Heyman “The less mobility in a county, the more overdose deaths. Moreover, it was two to three times as powerful a predictor as the next strongest predictor, either opioid prescription rates or unemployment.” 

A standard exponential equation accurately described the increasing trend in overdose rates from 2006 to 2021, he said. Remarkably, the same equation with virtually the same parameter values describes the increase in overdose rates for the entire U.S. from 1978 to the present, Heyman added.

Over this period, the drugs that were most toxic varied: cocaine, then prescription opioids, then fentanyl. In contrast, upward intergenerational income mobility steadily declined.

“We were surprised by the magnitude of county-by-county differences within states and that the sales of prescription opioids steadily declined from 2013 to 2021, yet overdose rates continued to increase at the pre-2013 rate.

Heyman said the findings don’t point to any simple solutions.

“However, other data, at both the individual and population level, reveal that if heavy drug users make it through their 20s, the majority find meaningful alternatives to drug use, particularly if they take advantage of self-help groups, find an occupation, and start raising a family: well-established but not widely known results,” Heyman said.

Heyman said the researchers have expanded the scope of their study and are now analyzing overdose predictors for the 3,109 counties in the 48 continental states. The results are similar to those for Midwest counties.

“The next challenge is to identify policies that can reverse susceptibility to intoxicating drugs,” Heyman said.