Trajectories of Growth Associated With Long-Term Stimulant Medication in the Multimodal Treatment Study of Attention-Deficit/Hyperactivity Disorder

Objective: To estimate long-term stimulant treatment associations on standardized height, weight, and body mass index trajectories from childhood to adulthood in the Multimodal Treatment Study of Attention-Deficit/Hyperactivity Disorder (MTA). Method: Of 579 children with DSM-IV ADHD−combined type at baseline (aged 7.0–9.9 years) and 289 classmates (local normative comparison group [LNCG]), 568 and 258 respectively, were assessed 8 times over 16 years (final mean age = 24.7). Parent interview data established subgroups with self-selected Consistent (n = 53, 9%), Inconsistent (n = 374, 66%), and Negligible (n = 141, 25%) stimulant medication use, as well as patients starting stimulants prior to MTA entry (n = 211, 39%). Height and weight growth trajectories were calculated for each subgroup. Results: Height z scores trajectories differed among subgroups (F = 2.22, p < .0001) and by stimulant use prior to study entry (F = 2.22, p < .001). The subgroup-by-assessment interaction was significant (F = 2.81, p < .0001). Paired comparisons revealed significant subgroup differences at endpoint: Consistent was shorter than Negligible (−0.66 z units /−4.06 cm /1.6 inches, t = −3.17, p < 0.0016), Consistent shorter than Inconsistent (−0.45 z units /−2.74 cm /−1.08 inches, t = −2.39, p < .0172), and the Consistent shorter than LNCG (−0.54 z units/+3.34 cm/ 1.31 inches, t = −3.30, p < 0.001). Weight z scores initially diverged among subgroups, converged in adolescence, and then diverged again in adulthood when the Consistent outweighed the LNCG (+ 3.561 z units /+7.47 kg /+16.46 lb, p < .0001). Conclusion: Compared with those negligibly medicated and the LNCG, 16 years of consistent stimulant treatment of children with ADHD in the MTA was associated with changes in height trajectory, a reduction in adult height, and an increase in weight and body mass index. Clinical trial registration information: Multimodal Treatment Study of Children With Attention Deficit and Hyperactivity Disorder (MTA); https://clinicaltrials.gov/; NCT00000388.