OBJECTIVES: Attention deficit hyperactivity disorder (ADHD) and the medications used to treat it are associated with obesity. Stimulants lead to weight loss, while antipsychotics and antidepressants lead to weight gain. Little is known, however, how alpha-2-agonists impact weight, or the independent effect on BMI of these four classes of medications, which are often prescribed concurrently. We aimed to estimate the proximal change in BMI associated with start of medication and to assess whether medication-specific departures in BMI varied by age and sex. STUDY DESIGN: We analysed longitudinal electronic health records from children (4–19 years) with an ADHD diagnosis seen at one healthcare system (2011–2018). Their BMI z-scores were fit as a cubic function of age via a mixed model, separately by sex and adjusting for race/ethnicity. From this model, we estimated annual changes in BMI-z after medication, allowing changes to vary by age and sex. RESULTS: Among the 22 714 children with ADHD (mean initial age = 10.0), 4335 (19.1%) were never prescribed ADHD medication. The others (80.9%) experienced departures in BMI-z after start of all four medication classes, which varied across age and sex (interaction P-values < .01). All medications had larger impacts at younger ages. As expected, decreased BMI-z was observed with stimulants, while antidepressants and antipsychotics led to BMI-z increases; alpha-agonists also were associated with BMI-z increases. CONCLUSIONS: This longitudinal study revealed that ADHD medications are independently associated with proximal changes in BMI-z after initiation, significantly varying by sex and age. Future research should study further the interactions of these medications on long-term impacts on obesity.
