YOSEMITE, CALIF. – Will my child become a dope fiend?
That's a common question Robert S. McKelvey, M.D., fields from parents of children who are prescribed a class II stimulant for attention-deficit hyperactivity disorder (ADHD).
“The answer is 'no,'” Dr. McKelvey said at a pediatric conference sponsored by Symposia Medicus. “The risk of kids who have properly diagnosed ADHD taking stimulants and becoming dope fiends is no different than [it is for] kids who do not have ADHD. The kids at risk are those who have ADHD” and are not on a prescribed drug treatment. “They have three times the likelihood of developing substance abuse problems,” he said.
Nonstimulant medications are an option for antisocial teens with ADHD, “although, at least in my view, they're not as effective as stimulants,” noted Dr. McKelvey, director of child and adolescent psychiatry at Oregon Health and Science University, Portland. Nonstimulant choices include atomoxetine, bupropion, clonidine, guanfacine, and the tricyclic antidepressants imipramine and nortriptyline.
Another question he commonly fields from parents is the effect of stimulants on children who have a chronic tic disorder such as Tourette's syndrome. “When I was in training, if you had tics, you had a history of tics, or even a family history of tics, we didn't start you on stimulant medication,” he said. “Now there are a couple of studies that show that if you have tics and you take stimulants, it's probably OK as long as the tics don't worsen. In many cases, the tics seem to [decrease in severity].”
Drug preparations in the stimulant class are derived from methylphenidate or dextroamphetamine. Methylphenidate is more widely used in the United States, but Dr. McKelvey noted that both agents are equally effective.
“You can't yet predict response, but it's possible that pharmacogenetics studies will give us a hand on that,” he said. “If one of them doesn't work, you try the other.”
A key point to remember about both agents is that they have very short half-lives. Maximal benefit on behavior occurs in 1–2 hours for agents derived from methylphenidate and 3–4 hours for agents derived from dextroamphetamine.
The sustained-release formulations appear to be as effective as the standard short-term formulations. The doses vary with the individual. There is some thought that academic performance (such as that associated with inattention) may respond to a lower dose than do restlessness and impulsivity, he said.
New, long-acting preparations enable once-daily dosing. These include Concerta, Metadate CD, Adderall XR, MethyPatch, and Focalin.
The most common adverse effect of stimulants is decreased appetite, which occurs in about 80% of children who take them. “The decreased appetite and weight loss can be stunning in some kids,” he remarked. “I've seen some very skeletal-looking little boys, and it can make you quite nervous.”
Long-term stimulant use may result in about a 1-cm decrease in height per year during the first 3 years of use, “but some of that is caught up,” Dr. McKelvey said. “More recent studies suggest there is perhaps a 1-cm decrease [in height] overall if you take stimulants long term.”
Insomnia is another common side effect, “so you tend to give it earlier in the day. You have to monitor heart and blood pressure. The things you're monitoring are height, weight, and blood pressure. It's pretty straightforward, but yearly, I usually check the white blood cell count,” he said.
He also warned against unproven therapies for ADHD, including megavitamins, biofeedback, sensory integration training, and optometric vision training. “There's a lot of malarkey out there.”