The proportion of inmates in jails with a moderate to severe stimulant use disorder—including addiction to methamphetamine—has surged in recent years, a study presented at the recent American Society of Addiction Medicine annual meeting suggests.

The study of inmates in two jails in rural North Carolina found over seven times more inmates with a substance use disorder met criteria for addiction to stimulants, including methamphetamine, in 2016 compared with 2008.

“These findings confirm anecdotal reports we were hearing from county sheriffs and correctional officers that they had noticed a considerable increase in meth-related crimes and meth lab seizures in rural areas,” said lead researcher Dr. Steven Proctor, Senior Research Professor and Associate Director of the Institutional Center for Scientific Research at Albizu University in Miami, Florida. “We don’t know whether a change in crime prevention strategy is driving law enforcement to prioritize meth-related crimes, leading to more arrests of people with stimulant use disorders, or whether increased use of meth is leading to an increase in meth-related crimes.”

Proctor said that although prevalence estimates of substance use disorders are provided annually for the non-institutionalized U.S. general population through nationally representative surveys, such methods are absent for correctional populations.

The study included data from 176 inmates in 2008 and 149 inmates in 2016. Proctor found alcohol was the most prevalent substance use disorder diagnosis in 2008, followed by cannabis and cocaine. Substance use disorders related to opioids and stimulants were relatively infrequent in 2008.

In sharp contrast, the substance use disorder category involving stimulants was the most prevalent diagnosis in 2016, followed by alcohol and opioids. The proportion of inmates with a moderate-severe opioid use disorder in 2016 was twice that of the prevalence of dependence in 2008.

The prevalence of cannabis use disorder remained relatively constant, but there was a dramatic drop in alcohol and cocaine use in 2008 and 2016.

Proctor noted these findings cannot be applied to the population at large. “It is difficult to track patterns of illicit meth use in the general population over the same period, because until 2015 the National Survey on Drug Use and Health only included questions about prescription stimulants, and didn’t ask about illicit meth use,” he said. “Further research is needed to determine whether these findings are applicable to non-correctional populations.”