The effects of methylphenidate on weight, height, and body mass index in Turkish children and adolescents with ADHD

Objective: The pathophysiological mechanisms underlying the effects of psychostimulants (methylphenidate) treatment on growth still remain controversial. We examined the long term effects of methylphenidate on height, weight and body mass index in Turkish children and adolescents with attention deficit hyperactivity disorder (ADHD). Methods: Participants (6-18 years, 330 boys, 103 girls) diagnosed with ADHD who received treatment with methylphenidate for at least 1 year at the Department of Child and Adolescent Psychiatry at Dokuz Eylul University Medical School were included in a retrospective study. Weight, height, and BMI z scores were converted to age- and gender-corrected z scores using norms from the Turkish population at baseline and last follow-up. Results: Height and weight standard deviation score (SDS) were reduced by treatment (baseline height-SDS (SDS]: 0.74 +/- 1.43, followup height-SDS [SDS]: -0.67 +/- 4.35, t-test p<0.001; baseline weight SDS [SDS]: 0.61 +/- 1.28, and follow-up weight-SDS [SDS]: -0.41 +/- 0.76, t-test p<0.001). There were no differences in BMI-SDS before and after stimulant treatment (baseline BMI-SDS [SDS]: 0.27 +/- 1.21, follow-up BMI-SDS [SDS]: -0.20 +/- 4.54, t-test p=0.353). However, considering whether patients were children (6-12 years) or adolescents (13-18 years) when they started medication, in the group of children, height and BMI was affected by treatment (baseline height-SDS [SDS]: 0.87 +/- 1.42; follow-up height-SDS [SDS]: -0.78 +/- 4.81]; p=0.002; baseline BMI-SDS [SDS]: 0.29 +/- 1.19; follow-up BMI-SDS [SDS]: -0.21 +/- 0.69; p<0.001). Results of multiple linear regression analysis which assess the possible contribution of the different treatment-related factors, only age starting treatment (B=-0.039, p=0.011) predicted final weight. Conclusions: We conclude that methylphenidate shows a negative effect on height and BMI in children. It was thought that the findings obtained at the end of the study might be helpful in assessing the growth parameters that may facilitate the course of the ADHD, and in the improvement of more efficient and permanent treatment approaches, and the adherence of patients to the treatment.