Boston—Pharmacists, who spend a relatively large percentage of their time dispensing stimulants for attention-deficit/hyperactivity disorder (ADHD), may wonder how effective the medications really are.

A new study in the Journal of Adolescent Health sought to answer that question, determining that stimulants have significant protective effects on functional outcomes in children and young adults with ADHD—and gender doesn’t appear to make any difference.

In fact, Massachusetts General Hospital–led researchers suggest that their results underscore the critical importance of early identification and treatment of ADHD in children of both sexes. The study team conducted an analysis of three previous studies of children and young adults to reach their conclusions on how stimulants reduce the development of mood disorders, school problems, conduct disorders, substance-use disorders, and other problems.

“Our study documents that early treatment with stimulant medication has very strong protective effects against the development of serious, ADHD-associated functional complications like mood and anxiety disorders, conduct and oppositional defiant disorder, addictions, driving impairments and academic failure,” explained lead author Joseph Biederman, MD, chief of the Pediatric Psychopharmacology and Adult ADHD Program at MGH and MassGeneral Hospital for Children. “In quantifying the improvement seen with stimulant treatment, it measures its potency in mitigating specific functional outcomes.”
Researchers identified limitations in previous studies of stimulant treatment for ADHD, including investigating outcomes only in boys or not calculating the magnitude of the protective effects of treatment.

For this study, participants were drawn from three independent samples—two similarly designed case–control, 10-year prospective follow-up studies of boys and girls with and without ADHD, and a cross-sectional randomized clinical trial of lisdexamfetamine’s effect on driving performance and behavior. All patients were evaluated with structured diagnostic interviews.

To measure psychopharmacologic treatment in the follow-up studies, the study team compiled information about each participant’s stimulant-medication use, age at onset, and age at termination of treatment. Patients in the driving study, meanwhile, underwent two driving-simulation assessments conducted premedication and after 6 weeks of treatment with lisdexamfetamine or placebo.

Researchers determined that the numbers needed to treat (NNTs) were very low, ranging from three to 10. They also identified no interaction effects for gender, and found that the adjusted NNTs mostly remained the same with the exception of any substance-use disorder, which increased after age was controlled for.

Specifically, the study found:
• Three participants with ADHD needed to be treated to prevent one from repeating a grade or developing conduct disorder, anxiety disorders, or oppositional-defiant disorder
• Four participants with ADHD needed to be treated to prevent one from developing major depression or experiencing an accident during the driving simulation
• Five participants with ADHD needed to be treated to prevent one from developing bipolar disorder, six to prevent one from smoking cigarettes, and 10 to prevent one from developing a substance-use disorder.

“Now we have the evidence allowing us to say that stimulant treatment of ADHD prevents the development of several very serious functional outcomes,” pointed out Biederman, who also is a professor of psychiatry at Harvard Medical School. “However, the impact on other serious outcomes—such as post-traumatic stress disorder, traumatic brain injury, suicide risk and employment success—still needs to be investigated.”

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