Prescription drug misuse later in life greatly increases risk for substance use disorder

Nearly half of people in a large U.S. study reported misusing prescription drugs between ages 18-50, which made them more likely to develop substance use disorder symptoms as adults––especially those whose misuse peaked later in life.

The new study from University of Michigan School of Nursing researchers recommends screening for prescription drug misuse and substance use disorder from adolescence through middle adulthood. Currently, the recommendation is to screen adults for unhealthy drug use in some instances, but not adolescents.

"The findings of the current study add to growing evidence that prescription drug misuse at any age, including adolescence, is a strong signal for substance-related problems, and that screening during adolescence can identify high-risk individuals before they develop more severe substance-related problems," said Sean Esteban McCabe, professor and director of the Center for the Study of Drugs, Alcohol, Smoking and Health at the U-M School of Nursing.

The study is the first known to examine prescription drug misuse over a 32-year period, McCabe said. It focuses on opioids, stimulants and sedatives/tranquilizers, which are among the most misused prescription drugs. They're most often misused during young adulthood but in recent years, prescription drug misuse has increased among older adults.

It's important to look at prescription drug misuse trajectories because there is wide variation and many reasons and patterns associated with this behavior over time. Studies that examine this behavior at one point in time do not adequately detect these variations, McCabe said.

"For example, some people experiment with prescription drugs and never use them again," he said. "Some misuse prescription drugs more frequently and develop problems and stop due to their consequences. Others misuse prescription drugs and develop consequences that last for decades."

Researchers identified unique prescription drug misuse trajectories associated with each drug class, and found that the risk for developing substance use disorder symptoms (cannabis, alcohol, opioids, stimulants, or other drugs) between ages 35-50, varied considerably across these trajectories.

"For example, we found that almost every individual (94%) in the group that misused prescription drugs frequently for a sustained period, and 70% of those in the trajectories that peaked in middle adulthood, had two or more substance use disorder symptoms between ages 35-50," McCabe said. "This is a very important finding. Clinicians and researchers are very interested in identifying subgroups of individuals with increased risk of developing substance-related problems."

By contrast, only 26% of people in the trajectory that didn't misuse prescription drugs frequently had two or more substance use disorder symptoms between ages 35-50.

Binge drinking, cigarette smoking and marijuana use were all associated with increased odds of belonging to a prescription drug misuse trajectory group. Black (non-Hispanic) adolescents and adults had lower risk of belonging to a trajectory group than white adolescents.

Researchers used data from 11 groups (26,575) of adolescents ages 18-50 who participated in the Monitoring the Future study. The study, "Trajectories of prescription drug misuse among U.S. adults from ages 18 to 50," appears in JAMA Network Open.