Varying Effects of Antipsychotics and Attention-Deficit Hyperactivity Disorder Medications on Body Mass Index among a Cohort of Autistic Youth.

Objective: Autistic adolescents and young adults (AYAs) are more likely to be obese than nonautistic peers. They are also more likely to be on psychiatric medications that can influence weight. The transition to adult health care is a challenge for autistic AYAs. The extent to which medications and transfer to adult care influence the weight of autistic youth is not well described. Study design: We assessed changes in body mass index (BMI) over time among a cohort of 216 autistic AYAs who had transferred from a pediatric hospital to an adult primary care clinic for autistic AYAs. We compared the mean BMI before and after transfer and used linear regression with main effects and age-related interaction terms to evaluate the contribution of transfer and psychiatric medications on BMI over time. Results: We found that mean BMI increased over time and that age and transfer to adult care both appeared to be drivers of BMI increases. We also found that psychiatric medications had complex effects on weight over time. For example, medications for attention-deficit hyperactivity disorder were associated with a lower BMI at age 16, but showed interaction with age such that each year of increased age beyond 16 mitigated the BMI decrease at age 16. Conclusions: These findings highlight the importance of evaluating for changes in side effects of medicines over time, particularly during the transition to adult care and support other calls to address healthy eating and activity habits with autistic AYAs in adolescence.