Review of: Man KKC et al, Lancet Psychiatry 2023;10(5):323–333

Study Type: Naturalistic, prospective, longitudinal, controlled study

Stimulants are safe and effective for childhood ADHD in the short term. Most studies, however, only look at safety up to 12 weeks. We have limited data on the long-term safety of stimulant treatment for kids, particularly regarding growth parameters. For instance, the well-known MTA study only followed children on medication for 14 months. This study offers fresh insight.

The study tracked the growth of 1,410 children and teens across five European countries over two years. Participants were divided into three groups: 1) new methylphenidate users with ADHD, 2) children with ADHD who did not intend to use methylphenidate, and 3) children without ADHD. Notably, none of the subjects received prior stimulant exposure. The average age was 9 years old (range 6–17 years). Subjects were predominantly male (76%) and White (93%). A European Union program provided public funding for this study, ensuring a level of objectivity.

After two years, methylphenidate showed no impact on growth velocity for height; however, there was a temporary reduction in weight velocity over the first six months of the study. Although the study did not account for family history of hypertension, methylphenidate was linked to small but significant increases in systolic and diastolic blood pressure and heart rate. In this study, methylphenidate did not exacerbate psychiatric or neurologic symptoms.

Carlat Take

Some patients are on stimulant medications for far longer than two years, and the very-long-term side effects are not clear. Still, this study offers some reassurance about the safety of methylphenidate for ADHD, particularly regarding growth, while supporting regular blood pressure and heart rate monitoring. This seems true even for younger children who may have a longer duration of exposure to side effects from stimulant medications.