This was an observational follow-up of children first enrolled in a large ADHD trial. The original study randomized 579 children aged 7.0 to 9.9 with combined-type ADHD. Years later, adult results were available for 476 of the ADHD group (82.2%). They were compared with 241 classmates who did not have ADHD (83.4%). People were checked mostly around age 25.
The ADHD group still had more symptoms as adults than the classmates. This gap was large (d=1.11). Parents tended to rate the adults as having more symptoms than the adults rated themselves (d=0.60).
Adults in the ADHD group were also a little shorter than the classmates, by about 1.29 cm (d=0.21). Within the ADHD group, those who had taken stimulant medication were shorter than those who took almost none, by about 2.55 cm (d=0.42). More consistent use was linked to slightly shorter height again. But longer medication use was not linked to fewer adult symptoms.
The researchers call these results hypothesis-generating, not proof of cause. The height link could reflect other differences between the groups. The effects were only seen up to age 25.
If you take or are considering stimulant medication, talk to a clinician about your own situation.
Source: James M. Swanson, L. Eugene Arnold, Brooke S. G. Molina, et al.. Young adult outcomes in the follow‐up of the multimodal treatment study of attention‐deficit/hyperactivity disorder: symptom persistence, source discrepancy, and height suppression. Journal of Child Psychology and Psychiatry (2017). doi:10.1111/jcpp.12684