Low-dose stimulants such as methylphenidate (Ritalin) have been used as ADHD medications for over 20 years, and more than 80% of diagnosed sufferers are prescribed stimulants. Ritalin works by increasing levels of dopamine in the brain, which leads to an improvement in attention and a decrease in distractibility, thus alleviating some of the symptoms of ADHD. However, there is a good deal of concern about the long term effects of stimulants in children with ADHD.
Stimulant addiction, withdrawal and rebound
Methylphenidate has the potential to be abused, and dosage should therefore be carefully regulated. It is capable of causing addiction, although this has not been reported at the low therapeutic doses recommended for the treatment of ADHD.
Use of Ritalin can cause lethargy during the day, but as the levels of the drug reduce at night time, or if the drug is withdrawn, children can suffer a “hyper” rebound with symptoms becoming worse than before. Stimulants can also interfere with the learning process and cause psychosis.
Decreased risk of substance abuse in later life
Many medical experts raised concerns that long-term use of stimulants to treat children with ADHD may lead to an increased risk of substance abuse in later life. However, a meta-analysis was published in 2003 scrutinizing the results of six prospective and retrospective studies. This meta-analysis found that the use of stimulants to treat ADHD seemed to have a protective effect, with subjects treated with stimulants showing significantly lower risk of developing substance abuse disorders.
Use of stimulants to treat ADHD is known to cause growth suppression during use, but these effects were initially thought to be short term and compensated for by growth rebound after treatment was discontinued. A 2007 study suggests that children with ADHD treated with Ritalin displayed stimulant-related decreases in growth rate when compared with non-medicated sufferers. The evidence discussed in this study did not support the growth rebound theory and therefore suggested that any growth-suppressing effects are likely to be permanent.
Along with other stimulants, Ritalin is known to cause mild tachycardia and increases in blood pressure. These effects could lead to a slight increase in the risk of cardiovascular disease later in life, but the effects are minimal and medical experts do not consider routine cardiovascular monitoring of patients taking Ritalin to be necessary. However there is some evidence to suggest that Ritalin may increase the risk of cardiac arrest.
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 WA Morton, GG Stockton “Methylphenidate Abuse and Psychiatric Side Effects” Journal of Clinical Psychiatry 2:159-164 (2000)
 PR Breggin “Talking Back to Ritalin” Common Courage Press (1998)
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