Latest research on medicines for ADHD
Publication Date:15/11/2007
You may have seen recent news reports saying that medicines for the condition attention deficit hyperactivity disorder (ADHD) don't work as well as doctors once thought, and may stunt children's growth. But have the reports got it right? We look at the latest research on treatments for ADHD. If you have a child with ADHD, this information can help you discuss treatment options with your doctor.
What do we know already?
ADHD is a condition that affects the way children behave. Children with ADHD have three basic problems:
- They can't pay attention
- They are hyperactive
- They act on impulse.
Of course, most children are like this at times. But children with ADHD act like this most of the time, which can cause problems. Children with ADHD, for example, can find it hard to keep up at school, and to make friends.
Medicines known as stimulants have been used for many years to treat ADHD. The types most used in the UK are Ritalin, Equasym XL and Concerta XL (also known as methylphenidate) and Dexedrine (dexamfetamine).
A study published in 1999 showed that children who'd been taking Ritalin for 14 months did better than children who'd had other, non-drug treatments such as behaviour therapy (a type of talking treatment that helps children and families cope with ADHD). They were less hyperactive and more able to concentrate, had better social skills and better reading scores. Two years after starting treatment, children taking Ritalin were still doing better, although the difference was smaller.
There have been concerns for many years that stimulant drugs might affect children's growth. But older studies didn't follow children long enough to find out. Some doctors thought that it might be ADHD itself that slows children's growth, whether or not children take medicines for it.
What does the new study say?
The researchers who did the 1999 study went back to look at what had happened to the children, 3 years after the start of the study. Most of the children were then aged 10 to 13 years old. Some of the children had continued with treatment, while others had changed to different types of treatment or stopped treatment altogether.
Researchers found three important results:
- Overall, the children's symptoms of ADHD, social and reading skills had improved during the three years since the study began, whether or not they took Ritalin.
- The children who had non-drug treatment during the study were doing as well as the children who were treated with Ritalin.
- The children treated with Ritalin hadn't grown as much as the children who had non-drug treatment. On average, they grew 2 centimetres less.
Tell me more about the study's findings
The researchers don't know why the benefits of taking Ritalin over non-drug treatment had disappeared after three years. It could be that:
- The children's symptoms just got better over time, with or without treatment. Some children do grow out of the symptoms of ADHD as they get older.
- All of the treatments might have worked, but at different speeds. So the children who had behaviour therapy but not Ritalin 'caught up' after three years.
- Some of the children who took Ritalin during the first year had stopped taking it by the third year. And some children who hadn't taken Ritalin during the first year started taking it. This confuses the results.
Children with ADHD who didn't take medicines were taller at the start of the study, and grew more during the study, than expected. That suggests that the condition itself doesn't slow children's growth. But children with ADHD who did take medicines grew less during the study than was expected. Over the three years, they grew about 2 centimetres in height and 2 kilograms in weight less than the children who didn't take medicines.
The researchers also compared children taking Ritalin to other local children who didn't have ADHD. The children who'd taken Ritalin for 3 years were on average 1 to 2 centimetres shorter and 1 kilogram lighter than the children without ADHD.
We don't know yet what effect taking ADHD medicines will have on the children's final, adult height. It's possible they may catch up during their teenage years. The researchers will continue following the children to adulthood, to find out.
Where does the study come from?
The research was carried out by researchers at the University at Buffalo, New York in the United States. It was published in the Journal of the American Academy of Child and Adolescent Psychiatry.
How reliable are the findings?
The original 1999 study was carried out very well. It included 579 children who hadn't been treated for ADHD before. Of these children, 485 were tested again for this new study.
The results for the first study were very reliable. And the results showing how well the children were doing after 3 years are likely to be reliable too.
But after the first 14 months, parents and children were free to decide which treatments they wanted. So it's harder to work out what effect Ritalin had during the second and third years. We don't know for sure what accounts for the results showing that the children were doing equally well, whichever treatment they'd had to start with.
What does this mean for me?
If your child is taking stimulant medicines for ADHD, or considering taking them, this study gives you more information about what long-term benefits and side effects you can expect. You can use this information to discuss your options with your child's doctor.
It's important to note that the study doesn't say that ADHD drugs don't work. The study showed children did do better during the first two years of treatment. But they were doing no better than children who'd had other types of treatment after three years. It's encouraging that most children in the study were doing better after 3 years of treatment, whether they had Ritalin or not.
The study only applies to Ritalin. Longer-lasting types of stimulant drugs, and other types of medicine for ADHD, were not used in the study because they weren't available when it started.
What should I do now?
If your child is taking medicine for ADHD and you are happy with the way it is working, there's no need to take any action. You might want to ask your doctor to monitor your child's growth while he or she is taking medicine. They can check whether your child is growing as fast as expected. Guidelines for doctors recommend that children's growth is checked regularly while taking stimulant drugs.
If you are concerned about your child's medication for ADHD, see your doctor to talk about your options.
From:
Jensen PS, Arnold LE, Swanson JM, et al. 3-year follow-up of the NIMH MTA study. Journal of the American Academy of Child and Adolescent Psychiatry. 2007; 46: 989-1002.
Swanson JM, Elliott GR, Greenhill LL, et al, Effects of stimulant medication on growth rates across 3 years in the MTA follow-up. Journal of the American Academy of Child and Adolescent Psychiatry. 2007; 46: 1015-1027.
To find out more, read our information on ADHD.
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© BMJ Publishing Group Limited ("BMJ Group") 2007. All rights reserved
This information does not replace medical advice. If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.
