• Science Update
Chronic use of stimulant medication to treat attention deficit hyperactivity disorder (ADHD) in children does not appear to increase risk for high blood pressure over the long term, but it may have modest effects on heart rate, according to follow-up data from the NIMH-funded Multimodal Treatment Study of Children with ADHD (MTA). The study was published online ahead of print Sept 2, 2011, in the American Journal of Psychiatry.
The MTA was the first major multi-site trial comparing different treatments for ADHD in childhood. The initial results of the 14-month study, in which 579 children were randomly assigned to one of three intensive treatment groups (medication management alone, behavioral treatment alone, a combination of both) or to routine community care, were published in 1999. The researchers found that medication management alone or in combination with behavioral therapy produced better symptomatic relief for children with ADHD than just behavioral therapy or usual community care.
After the study ended, participants returned to community treatment and were free to pursue whatever treatment course they wished. MTA researchers gathered follow-up data from MTA study participants at 2, 3, 6, 8, and 10 years after study entry.
ADHD is often a chronic condition that continues into adolescence, so some children take stimulants for years. Because stimulants can affect the heart, doctors are concerned about the possible risks for rapid heart rate, hypertension (high blood pressure) or other cardiovascular effects after many years of use. But studies have been inconsistent about whether the effects are long-lasting.
For this most recent data analysis, Benedetto Vitiello, M.D., of NIMH, and MTA colleagues examined the MTA follow-up data to determine if there was an association between chronic use of stimulant medication and changes in blood pressure or heart rate over a 10-year period.
Results of the Study
At the end of the 14-month study, children who were randomized to stimulant treatment in the study had, on average, higher heart rates compared to the children who were randomized to non-medication or community care. Heart rates for the children who continued to take stimulants after the end of the study were slightly elevated at subsequent checks, but they did not have an abnormally elevated heart rate (e.g., tachycardia).
The researchers concluded that stimulant medication did not appear to increase the risk for abnormal elevations in blood pressure or heart rate over a 10-year period. However, because some epidemiological studies have indicated that even modest elevations in heart rate may increase a person’s lifetime risk for cardiovascular problems, the persistent effect of continuous stimulant treatment on heart rate should not be dismissed.
The results of this study indicate that the effect of stimulants on heart rate can be detected even after years of use, suggesting that the body does not get completely used to it. However, after 10 years of treatment, researchers found no increased risk for hypertension. In addition, none of the children reported any adverse cardiovascular events over the 10-year period.
The researchers do note that the effect on heart rate may be clinically significant for individuals who have underlying heart conditions. Therefore, children taking stimulants over the long-term should be monitored regularly for potential cardiovascular complications.
Vitiello B, Elliott GR, Swanson JM, Arnold E, Hechtman L, Abikoff H, Molina BSG, Wells K, Wigal T, Jensen PS, Greenhill LL, Kaltman JR, Severe JB, Odbert C, Hur K, Gibbons R. Blood pressure and heart rate in the multimodal treatment of attention deficit/hyperactivity disorder study over 10 years. American Journal of Psychiatry. Online ahead of print Sept 2, 2011.