Youth who take Ritalin, Adderall or other stimulant medications for ADHD over an extended period of time early in life are no more at risk for substance abuse in later adolescence than teens without ADHD, according to a University of Michigan study.

The findings also show that teens who start using stimulant medications for attention deficit hyperactivity disorder for a short time later in adolescence — during middle or high school — are at high risk of substance use.

The U-M research is believed to be the first national study to compare early-use and longer-duration stimulant medication therapy with nonstimulant therapy for ADHD.

A large sample size of high school seniors also meant researchers could separate doctor-prescribed ADHD medication use by gender. The results show no gender differences in the overall associations between stimulant medication therapy for ADHD and risk of substance use, said Sean Esteban McCabe, a research professor at the U-M Institute for Research on Women and Gender.

More than 40,000 individuals from 10 cohorts nationwide between 2005 to 2014, answered questions about ADHD medication use and recent substance use as part of the Monitoring the Future study.

Among the findings:

• Nearly one in eight high school seniors in the United States have used stimulant or nonstimulant medication therapy for ADHD.

• Males are more likely to use stimulant medication therapy for ADHD, while no gender differences were found for nonstimulant medication therapy.

Given that higher substance-use behaviors are associated with later initiation of stimulant medications for ADHD during adolescence, the researchers recommend monitoring this later initiation subgroup carefully for pre-existing risk factors or the onset of substance use behaviors.

McCabe collaborated with Kara Dickinson, former intern at the U-M Institute for Research on Women and Gender; Brady West, research associate professor at the U-M Institute for Social Research; and Dr. Timothy Wilens of Massachusetts General Hospital and Harvard University.

The findings appear in the current issue of the Journal of the American Academy of Child & Adolescent Psychiatry. The National Institute on Drug Abuse and National Institutes of Health supported research grants for the study.