Importance: As attention-deficit/hyperactivity disorder (ADHD) is commonly diagnosed in childhood, methylphenidate (MPH) is the most widely prescribed treatment. Although effective for symptom management, concerns remain about an association with growth and body composition.
Objective: To investigate the associations of the prevalence of ADHD and MPH use in childhood with body mass index (BMI) and height at adulthood (aged 20 to 25 years).
Design, setting, and participants: In this nationwide retrospective cohort study, data of children aged 6 to 11 years and adolescents aged 12 to 19 years with newly diagnosed ADHD from the Korean National Health Insurance Service were included between January 2008 and December 2013. Exact matched controls of children and adolescents without ADHD were also included. Their cumulative medication exposure over a 4-year period was assessed, and their height and weight during adulthood were subsequently evaluated from January 2018 to December 2022. Data extraction and statistical analyses were conducted from November 2024 to May 2025.
Exposures: Diagnosis with ADHD and MPH prescriptions (cumulative days of MPH use, <1 year or 1 to 4 years, within 4 years after the diagnosis).
Main outcomes and measures: The primary outcomes were BMI (calculated as weight in kilograms divided by height in meters squared) and height (in centimeters) at adulthood, assessed as continuous variables (crude mean [SD] and adjusted mean [95% CI]) and binary outcomes (adjusted odds ratio [AOR] [95% CI]). Measures for being overweight and obese were a BMI of 25 or more for males and 23 or more for females; measures for having short stature were a mean (SD) less than 174.4 [5.5] cm for males and less than 161.8 [5.3] cm for females.
Results: In this cohort study of 34 850 youths (n = 12 866 prepubertal children aged 6-11 years; mean [SD] age, 9.3 [1.4] years; 9329 males [72.5%]; and n = 21 984 adolescents aged 12-19 years; mean [SD] age, 14.5 [1.8] years; 14 633 males [66.6%]), prepubertal children with ADHD compared with those without ADHD had a higher adjusted mean BMI (24.3 [95% CI, 24.2-24.4 vs 23.3 [95% CI, 23.2-23.4]; P < .001) but not a significantly shorter height (167.8 cm [95% CI, 167.7-167.9 cm] vs 167.9 cm [95% CI, 167.8-168.0 cm]; P = .10) at adulthood. Those with ADHD who received MPH therapy compared with participants without ADHD had greater odds of a BMI classified as overweight and obese (AOR, 1.60 [95% CI, 1.51-1.71]; P < .001) and short stature (AOR, 1.08 [95% CI, 1.02-1.15]; P = .01) at adulthood.
Conclusions and relevance: In this cohort study, patients with ADHD, particularly those treated with MPH, had a higher BMI and shorter height at adulthood than individuals without ADHD. Although the observed height difference was clinically small in both sexes and age groups, the findings suggest that long-term MPH exposure may be associated with growth and body composition, highlighting the need for regular monitoring of growth.