Stimulant Medication Misuse 'Starts Earlier Than Thought'

Liam Davenport

June 16, 2015

The misuse of stimulant medications typically prescribed to treat attention-deficit/hyperactivity disorder (ADHD) and other similar prescription drugs starts earlier than previously thought, new research shows.

Investigators found that the peak age of initiation of these medications is from 16 to 19 years and that females are more likely to misuse stimulants, particularly diet pills, than males, with a peak incidence at age 18 years, twice that of their male counterparts.

Study author Elizabeth Austic, PhD, a postdoctoral fellow in the Injury Center, Department of Emergency Medicine, University of Michigan Health System, writes: "These results draw attention to the timing of potential school-based and practice-based initiatives."

"If these initiatives are started in early adolescence, it may become possible to reduce the risks associated with youths starting to misuse someone else's prescription or misuse their own prescription without a physician's knowledge."

The study was published in the July issue of Drug and Alcohol Dependence.

Sex Difference Surprising

Having previously identified the peak ages for starting the nonmedical use of prescription opioids to be age 16 years, which was earlier than expected, Dr Austic examined data from the National Surveys on Drug Use and Health 2004-2012, which is a nationally representative series of cross-sectional surveys.

Pooled across the years of the survey were 250,910 respondents aged 12 to 21 years. Among other things, they had answered questions about their nonmedical use of three classes of stimulants: methamphetamine; prescription diet pills, such as amphetamines; and methylphenidate. They were also asked about their usage of a series of stimulants.

A meta-analytic approach was then used to produce age-, year-, and cohort-specific risk estimates at the population level of the first-time, nonmedical use of prescription stimulants.

Dr Austic found that the risk of starting the nonmedical use of prescription stimulants was between ages 16 and 19 years, with approximately 0.7% to 0.8% of young people reporting have used these medicines for the first time in the past 12 months. Ages 12 to 15 years and 20 to 21 years were associated with smaller risk estimates, ranging from 0.1% to 0.6%.

Interestingly, females were more likely to start the nonmedical use of prescription stimulants than males (odds ratio [OR], 1.35; P = .001). At 18 years of age, the peak annual incidence of initiation was almost twice as high among females as among males, at 1% vs 0.5%.

Dr Austic was surprised that rates of initiation were higher among females, because males are more often diagnosed with ADHD and are prescribed ADHD medication more often. "But as to why it's higher, I can only speculate," she told Medscape Medical News.

Further analysis indicated that females were almost twice as likely to initiate the nonmedical use of diet pills than males, at 24.1% vs 12.8% (OR, 2.17; P = .001). Males were more likely to initiate use of Adderall (a combination of amphetamine aspartate, amphetamine sulfate, dextroamphetamine saccharate, and dextroamphetamine sulfate manufactured by Shire and Teva), at 25.9% vs 18.5% (OR, 1.55; P = .021).

Finally, Dr Austic found that non-Hispanic white and Native American individuals were more likely to start the nonmedical use of stimulant medicines (OR, 2.15 [P < .001] and 2.31 [P = .035], respectively).

No Academic Boost

One crucial aspect is that many adolescents are misusing these drugs in the mistaken belief that doing so will help them to perform better at school.

"It's coming out in the research literature, but it's not really common knowledge yet that the way that young people misuse prescription stimulants does not help them study," she said.

"It doesn't help improve their grades.... Mostly, young people who are misusing these medications actually have lower grades than people who don't," Dr Austic added.

She explained: "They are often using it to cram to the last minute or make up for poor study skills, or maybe they have a hangover in the morning and they want to get up and be able to go take a test or focus in school."

"So the way that young people actually tend to misuse prescription stimulants is not giving a big academic boost."

Dr Austic noted that the misuse of prescription stimulants on college campuses is "commonplace and accepted." However, the current findings indicate that prevention programs could be successfully targeted at younger individuals.

"Some of the most effective interventions have been timed around the years leading up to your first-time use," she said. "So you identify in the population when most people are starting to experiment with something for the first time, and then you design your intervention for the 2 or 3 years leading up to those years."

She added: "Then if you can convince young people to not misuse for the first time, you can often prevent a lot more misuse in the long run than if you wait until the freshman year of college."

Important Implications

Welcoming the findings, Sherry H. Stewart, PhD, professor in the Department of Psychiatry and the Department of Psychology and Neuroscience at Dalhousie University, Halifax, Canada, said the study has "some pretty important clinical implications."

"It clarifies a few things, because prior to this study, we assumed that the peak age was in the college years...due to the relatively high prevalence among college students. This study takes a different tack because they're not looking for the prevalence but instead looking for the incidence," she told Medscape Medical News.

"That's an important distinction, because, when you look at incidence, it can really tell you when you want to time your prevention programming. So if you know where the peak age at which people are starting for the first time, you can target your programming."

However, Dr Stewart believes that the study has a few limitations, saying: "It makes suggestions about the why's, but it really doesn't address the why's."

Nevertheless, it is possible to detect some patterns from the findings, such as the differences among the sexes in initiating misuse.

"If you take a look at these patterns, it can start to tell you some information that makes suggestions about their motivations," she said.

"So it looks like girls at that particular age using that particular type of stimulant is probably around weight loss concerns."

"But I would suggest probably the motivations are changing across development.... There is work showing that one of the main motivations is around study aid...and [age 16 to 19 years] may be an age where there's an onset of that particular motive."

Dr Stewart also said that another reservation about the study is with regard to the use of the term "misuse," because there are a number of different definitions that term.

"In this particular article, they talk about use without prescription from a physician for nonmedical use, and also they included use for the feeling, like the high," she stated. "But there's a number of other potential definitions or things that can be considered."

For example, misuse may include use with alcohol or with other drugs, as well as polydrug use. Another definition relates to an individual's having a prescription for a drug but using it at a different dose. Misuse may also involve the route of administration, such as intranasal use.

The development of this article was supported by National Institute on Drug Abuse grants and a National Institutes of Health grant. The authors have disclosed no relevant financial relationships.

Drug Alcohol Depend. 2015:152;224-229. Abstract


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