• Attention deficit hyperactivity disorder (ADHD) affects millions worldwide, and many worry that ADHD medication might increase the risk of self-harm
• The team led by Aston University’s Dr Adrienne Chan and Professor Ian Wong analysed data from Hong Kong, New Zealand, South Korea, Taiwan and the UK
• They found that the risk of self-harm is highest before people start ADHD medication.

The risk of self-harm amongst people with attention deficit hyperactivity disorder (ADHD) is highest before people start ADHD medication, rather than after treatment begins, according to new research led by Aston University.

The researchers, led by Dr Adrienne Chan, a pharmacy lecturer, and Regius Professor Ian Wong at Aston Pharmacy School, were seeking to address fears that taking ADHD medication raises the risk of self-harm, following conflicting evidence from previous studies of ADHD medication. Millions of adults and children worldwide have ADHD and these concerns can influence whether people start or continue with treatment, despite more recent studies being more reassuring.

The multinational collaboration saw the Aston University researchers partnering with groups from UCL in the UK, the University of Hong Kong, the University of Auckland in New Zealand, Sungkyunkwan University in South Korea, and National Cheng Kung University in Taiwan. There were also collaborators from the Seoul National University in South Korea, the University of Melbourne in Australia, Rutgers University in the US, the University of Waterloo in Canada, the Chinese University of Hong Kong and Macau University of Science and Technology.

In one of the largest multinational studies of ADHD medication safety, the research team analysed data from more than 460,000 people from the healthcare systems in Hong Kong, New Zealand, South Korea, Taiwan and the UK, who had begun a course of ADHD medication and had a record of self-harm between 2001–2020. They compared three periods of ADHD medication exposure – the 90 days before treatment began, the first 90 days of treatment use and the subsequent treatment period – with periods of non-exposure.

The highest risk of self-harm occurred during the 90 days immediately before starting treatment in all five healthcare systems, with lower, although still elevated, risks after treatment began. These consistent findings do not support ADHD medications as the main driver of self-harm.

The researchers say that the findings highlight the importance of closely monitoring people with ADHD, particularly those whose symptoms are worsening before they start treatment, so that support can be provided before self-harm occurs.

Additionally, the study has established an international research platform that can answer other important questions about medication safety. Future work will examine a wider range of health outcomes, including what happens when people stop or restart treatment, and whether ethnicity and socioeconomic disadvantage contribute to inequalities in ADHD care across different healthcare systems.

Dr Chan said:

“People often worry that ADHD medication itself increases the risk of self-harm. What our findings suggest is that many people are already at their highest risk before treatment even begins. This highlights an important opportunity for earlier intervention. Recognising that vulnerable period could help us provide support earlier, when it may make the greatest difference.”

Professor Wong said:

“At Aston, we are committed to using big data not simply to answer scientific questions, but to generate evidence that helps clinicians, informs policy, and ultimately benefits patients. This study reflects that vision by bringing together expertise from five healthcare systems using a common scientific approach while keeping patient-level data securely within each country. It demonstrates how international collaboration can generate robust evidence to improve patient care while respecting patient privacy and the highest standards of data governance.”

To read the full paper, ‘ADHD medication use and risk of self-harm: a multinational self-controlled case series study’ in BMJ Mental Health, visit https://mentalhealth.bmj.com/content/29/1/e302819.