Whether students misuse prescription stimulants because they are self-medicating attention-deficit hyperactivity disorder (ADHD) or because they have a substance use disorder (SUD) has been a question for years. A recent study, however, has shed light on the controversy, showing that half of these students actually have an SUD. In fact, the students who misuse these medications prefer immediate-release to extended-release stimulants, and use them repeatedly, not just once or twice, indicating addiction.

Nonmedical use of stimulants is misuse, and in the college setting, where students may be misusing these medications in order to stay up late and study, it turns out that most, compared to controls, actually have psychiatric disorders, including ADHD.

The study, “Nonmedical Stimulant Use in College Students: Association with Attention-Deficit/Hyperactivity Disorder and Other Disorders,” was published in the July issue of the Journal of Clinical Psychiatry. Lead author Timothy E. Wilens, M.D., told ADAW that self-medication does exist. “I believe that a group are self-medicating their ADHD,” said Wilens, noting that the risk for ADHD was twice as great for misusers as for controls. He noted that in analyses he and his colleagues will be presenting at the American Academy of Child and Adolescent Psychiatry meeting in October, there was also “higher risk for clinical and neuropsychologically derived executive function deficits in misusers relative to controls.” But the data also support other research in which high rates of SUDs are found in stimulant misusers, said Wilens, who is chief of the Division of Child and Adolescent Psychiatry and co-director of the Center for Addiction Medicine at Massachusetts General Hospital.

Background

Up to 8 percent of college students are estimated to have ADHD, and stimulant medications are among the first-line treatments for this disorder in adolescents and young adults. However, there are few studies specifically evaluating ADHD and other diagnoses in college students misusing stimulants. To examine the gaps in research, this study looked at a heterogeneous sample of college students, focusing on ADHD and psychiatric and substance use disorders, the type of stimulants misused and the context of the misuse.

The researchers hypothesized that the stimulant misusers, compared to controls, would have higher rates of ADHD symptoms, or an actual ADHD diagnosis; that the rates of SUDs would be higher in stimulant misusers than in controls; and that stimulant misusers would have higher rates of other psychopathology than controls. In addition, they hypothesized that there would be a greater use of immediate-release compared to extended-release stimulants.

Study details

The researchers recruited 100 college students who misused stimulants but were not receiving them pursuant to a diagnosis of ADHD, and 200 controls who were not being treated with stimulants and had never misused them but for whom a prior diagnosis of ADHD was not exclusionary. Stimulants included those with Food and Drug Administration indications for ADHD: amphetamine (dextroamphetamine, lisdexamfetamine, immediate- and extended-release mixed amphetamine salts and immediate- and extended-release methylphenidate) but did not include modafinil, armodafinil, methamphetamine or other stimulants (such as cocaine and 3,4-methylenedioxymethamphetamine).

Assessments were made using DSM-IV-based interviews by raters with training and supervision from the senior investigator. Raters and reviewers were blinded to status.

Results

The final sample included 100 misusers and 198 controls (two were dropped because it turned out they had possibly misused stimulants). Misusers were more likely to have ADHD (27 percent vs. 16 percent) and conduct disorder (10 percent vs. 3 percent).

Stimulant misusers were 2.9 times more likely than controls to have an SUD, and 5.4 times more likely to report a combined alcohol and drug use disorder.

Implications

The study partially supported the researchers’ hypotheses that misusers are at higher risk for ADHD and/or multiple SUDs. These misusers were also more likely to have a poorer quality of life related to controls.

Standard survey studies use a very different method of quantifying ADHD than the structured diagnostic interviews used for this study. Still, the results are consistent with survey studies, which also suggest a high rate of self-medication of ADHD.

“Some misusers may be driven to use stimulants in an effort to achieve better grades, increase productivity, and self-treat their threshold or subthreshold ADHD, which are motivations not typically associated with the abuse of alcohol or other drugs,” the researchers wrote. They speculated, however, that SUDs themselves can result in academic problems, which result in stimulant misuse to improve already failing performance.

The researchers in this study, however, did not suggest that stimulant misusers are all self-medicating for ADHD. Nearly half of stimulant misusers have an SUD, most commonly involving alcohol or marijuana, followed by prescription stimulant misuse. Previous research has found that the onset of an SUD precedes stimulant misuse. This study found that nonmedical use of stimulants may be associated with a separate SUD that necessitates referral to treatment. The researchers go on to suggest that stimulant use disorders may be unique among SUDs, because “the behaviors and causalities may be entirely unrelated” to other SUDs. “Regardless, given the high rates of substance use disorder in our groups, college students who misuse stimulants should be systematically screened for alcohol, stimulant, and other substance use disorders,” they said.

Despite limitations such as a small sample size, the fact that the sample (metropolitan Boston) may not generalize to other areas and interviews instead of biological testing to determine SUDs, the study shows that “college students who misuse prescription stimulants are clearly struggling” due to the high rates of ADHD and SUD and lower quality of life associated with stimulant misuse.

Wilens told ADAW that he was surprised that the rates of ADHD were so low. “I expected higher rates,” he said. “Probably most surprising was that of the subsample we intensely examined for stimulant use disorder, over one-half of misusers actually had a diagnosable stimulant use disorder,” he said. “In other words, it is not true that stimulant misusers only use once or twice. In fact, a sizeable number actually may have an addiction to the stimulant they are misusing — it may not be so benign.”

This is one of the few studies that has examined stimulant misusers in depth and in a controlled manner, noted Wilens. In particular, these misusers preferred immediate-release vs. extended-release stimulants, which suggests that practitioners should not prescribe immediate-release products to higher-risk groups.

Disentangling self-medication from addiction is particularly complicated with prescription stimulants, Wilens admits. However, ADHD does exist among misusers, and can’t be discounted. “Essentially every study I complete in which there is some instrument of self-medication shows a signal of self-medication,” Wilens said.