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    Effects of ADHD Treatment May Vary Over Time

    ADHD Medications Effective, but May Also Stunt Growth

    Explaining the Truth Behind the Numbers continued...

    "At 24 months after the start of treatment, the effects of various treatments seem to be coming together," says Swanson.

    But researchers say changes in medication use such as starting and stopping medication may explain the changes seen over time with the treatments.

    "We don't think that treatments become ineffective over time," says Swanson. "What we see is that a lot of people stop treatment, and then the efficacy is not permanent and it tends to go away when the treatment stops."

    Swanson says many of the children who were initially assigned to treatment with ADHD drugs stopped taking them after the first phase of the study, and many of those in the behavioral group started taking them during the follow-up period.

    Further analysis showed that children who stopped taking their ADHD medications tended to have a greater reduction in benefits, children who went on medication showed improvement, and children who stayed with the same treatment stayed about the same, whether they were on medication or

    ADHD Medications May Stunt Growth

    The study also showed that children who took ADHD medications grew at an average of 5 centimeters per year compared with the 6 centimeters per year seen in unmedicated children.

    Researchers say those findings are in line with previous studies that have shown similar short-term effects on growth. But this is the first major long-term study to show the effect for two years of using the drugs.

    "We want to be cautious because we don't know if in the long run children might catch up or not," says Swanson. For example, he says that children using ADHD medications might only experience a delay in growth that only very long-term studies might be able to pick up.

    Interestingly, researchers also found that unmedicated children with ADHD actually tended to grow taller than children without the condition, which suggests that any potential negative effect of ADHD medications on growth may be less obvious in these children.

    "Whether that's going to outweigh the clear benefits that I think this study and many others have shown for using medication in the treatment of ADHD over the long-term is one of those things that we will have to continue to look at," says researcher Glen R. Elliott, MD, PhD, director of the Children's Center at Langley Porter, University of California, San Francisco.

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