Long-term safety confirmed for common ADHD medication

Long-term safety of common ADHD medication for children and adolescents, global team finds. Long-term use of methylphenidate, the most commonly prescribed medication for treating ADHD, does not increase the risk of adverse developmental and psychiatric outcomes in children and adolescents, an international research team has found. The findings have led experts to argue for the drug’s inclusion on a global Essential Medicines list.

Published in The Lancet Psychiatry, a controlled, longitudinal study has shown that methylphenidate – sold under brand names Ritalin, Concerta and others – treatment for children and adolescents over two years did not lead to adverse growth and development, psychiatric, or neurological outcomes.

ADHD – Attention-deficit/hyperactivity disorder – is a chronic neurodevelopmental condition that affects seven percent of children and two percent of adults worldwide, and includes attention and organisational difficulties, hyperactivity and impulsiveness.

Left untreated, people with ADHD can be prone to a wide range of adverse outcomes like mental illness, low self-esteem, self-harm, substance misuse, exclusion from school and educational underachievement, and difficulties with employment and relationships.

Methylphenidate was rejected by the World Health Organization (WHO) for inclusion in their Essential Medicines List (EML), because of concerns about the limitations and quality of available evidence of the medication’s harms and benefits.

The European Union-funded Attention-Deficit-Hyperactivity-Disorder-Drugs-Use-Chronic-Effects (ADDUCE) project sought to address concerns about the long term safety of the drug. The ADDUCE project has undertaken a two-year naturalistic study to assess adverse effects of methylphenidate on growth and development, psychiatric, neurological, and cardiovascular health outcomes.

Project lead University of Melbourne Professor David Coghill, Financial Markets Foundation Chair of Developmental Mental Health, Department of Paediatrics, worked closely with ADDUCE project collaborators from the University of Hong Kong and across Europe. Professor Coghill said that ADHD is a lifelong condition for many people, that if untreated can result in serious negative outcomes.

“Because of this, people with ADHD often need to remain on treatment for several years. While we already knew that methylphenidate is a very effective treatment for ADHD that is safe and well tolerated in the short term, we had very little data about the longer-term safety,” Professor Coghill said.

“These findings that longer-term treatment with methylphenidate is safe and well tolerated are very reassuring. Together with our other studies, which have demonstrated the effectiveness of methylphenidate and other ADHD medication, these data strengthen the argument for the WHO to reconsider their decision to include methylphenidate in the Essential Medicines List.”

Exclusion of these medications from the WHO list makes access to ADHD medications difficult for people with ADHD in many parts of the world. This was highlighted in a linked study also led by the University of Hong Kong and the University of Melbourne, published this month in in The Lancet eClinicalMedicine.

The study found high-income countries consume ADHD medication at ten times the rate of middle-income countries. Rates of ADHD medication consumption were much lower in middle-income countries than the prevalence of ADHD, strongly suggesting disparities for ADHD medication access by a country’s income level.

University of Hong Kong Professor Ian CK Wong, Head of the Department of Pharmacology and Pharmacy, said: “We looked at the global patterns and trends of ADHD medication use, particularly in middle-income countries and investigated the trends of ADHD medication consumption for 64 countries from 2015 to 2019,”

“People with ADHD in middle-income countries are disproportionately affected as these children are already at economic and educational disadvantages and at the highest risk of adverse effects from ADHD,” Professor Wong said.

Professor Coghill believes that inclusion of methylphenidate in the Essential Medicines List would help address inequities in access to ADHD medications.