Debate: Are Stimulant Medications for Attention-Deficit/Hyperactivity Disorder Effective in the Long Term? (For).

Long-term effectiveness studies for ADHD medications are complicated to design well, and no single study design will capture the entire picture. Although randomized controlled trials are the highest level of evidence, most authorities agree that, when you have treatments as efficacious as the ADHD medications (methylphenidate and amphetamine derivatives and prodrugs, atomoxetine, guanfacine, and clonidine), it is neither practical nor ethical to conduct long-term placebo-controlled RCTs. As a consequence, almost all of the RCT evidence for ADHD medications relates to short-term studies. Although these provide strong evidence for short-term efficacy,1 they do not speak to long-term effectiveness. The European Medicines Agency (EMA) recognized the need for additional evidence of long-term effects before granting licenses for medications that will usually be required to be taken for several years. They therefore introduced a requirement for companies to demonstrate longer-term efficacy. This has generally been done through the use of randomized withdrawal designs that are designed to demonstrate continued efficacy over a period of 6 to 12 months. Several of these have been completed and published, all of which, as expected, demonstrate continued efficacy.2 The EMA also insisted that all new ADHD medications demonstrate continued effectiveness, and that adverse effects and safety be assessed up to 2 years. Again the studies completed so far support continued effectiveness, and, although highlighting the presence of common, expected adverse effects, have not identified any new safety signals or unexpected problems in targeted areas such as growth and cognition.3.