Children who are underweight are more likely to stop taking their ADHD medication within a year. These are the findings of a study conducted at the University of Gothenburg on methylphenidate, a common pharmacological treatment in ADHD. Behind the discontinuations are clear differences in dosage that can also be linked to gender and age.
Methylphenidate helps the brain to regulate focus and impulse control. It is the most commonly used medicine for ADHD and is the active substance in Concerta, Ritalin, Medikinet and other medicines. The tablets or capsules are approved for children from 6 years of age, and for adults.
The current study, published in the journal Pediatric Drugs, included 1,741 children and adolescents who had started treatment with methylphenidate. The data included information on gender, age, BMI and medicine doses. For 612 children, follow-up data on prescription and BMI 6–12 months after treatment initiation were also available.
Clear differences in the dosages
The results show that children and adolescents with overweight and obesity received slightly higher doses of methylphenidate on their first prescription, but when the researchers considered the weight of the children and calculated the dose per weight, they found that children and adolescents with overweight and obesity tended to receive lower weight-adjusted doses.
For the group of children and adolescents with underweight, the opposite was true. When their first doses were considered according to weight, it was found that in practice the doses were higher than for those of higher weight.
In the next step, when it was time for follow-up prescriptions, absolute dose increases were highest in children and adolescents with obesity and lowest in children and adolescents with underweight.
The study also shows that at follow-up, girls received higher doses than boys, both absolute and weight-adjusted doses, while children over 12 years received higher absolute but lower weight-adjusted doses than children under 12 years.
Weight, gender and age matter
Leading the study are Julia Izsak, Researcher and Resident in Clinical Pharmacology, and Jenny Kindblom, Consultant and Professor of Clinical Pharmacology at the University of Gothenburg and Sahlgrenska University Hospital:
“There is a significantly higher proportion of children and adolescents with underweight who discontinue treatment during the first year, compared to the group of normal weight. In addition to this, it is also clear that girls and children over the age of 12 are more likely to discontinue their treatment within a year,” Julia Izsak concludes.
The researchers conclude that the findings highlight the need for further studies on how dosage affects the efficacy and safety of methylphenidate treatment for ADHD in children and adolescents, including those with underweight, overweight or obesity.
“There are major gaps in knowledge regarding medicines to children and adolescents. Our results underline the importance of considering children's individual circumstances when starting and monitoring medical treatment for ADHD. Through further research, we hope to increase knowledge and contribute to more accurate treatment strategies for children and adolescents with different weight status,” says Julia Izsak.