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Medication for attention deficit hyperactivity disorder (ADHD) is associated with reduced risk of several adverse life events, such as suicidal behaviour and substance misuse, according to study results published in the BMJ.
The research, published on 13 August 2025, used data from 148,581 people in Sweden aged between 6 and 64 years who had been diagnosed with ADHD between 1 January 2007 and 31 December 2018.
Patient data were taken from several databases, including the National Patient Register and Prescribed Drug Register.
Researchers looked at people who either did or did not start drug treatment within three months after their ADHD diagnosis and followed them up for a period of two years.
More than half (56.7%) of people diagnosed with ADHD started drug treatment, with methylphenidate being the most commonly prescribed drug.
Among those who took medication, the authors found statistically significant reductions in first incidences of suicidal behaviour, substance misuse, transport accidents and criminal convictions.
For suicidal behaviours, the weighted incidence rates were 14.5 per 1,000 person years among people who took medication, compared with 16.9 in those who did not.
For substance misuse, the incidence rates per 1,000 years were 58.7 in people who took medication compared with 69.1 in those who did not.
For transport accidents, data show the rates were 24.0 compared with 27.5; and for criminal convictions, 65.1 compared with 76.1.
There were no significant differences in the rate of accidental injuries between the two populations.
Among people who had previously experienced an incident of one of these five outcomes, reduction rates following medication onset were more pronounced and seen across all event types, including accidental injuries.
The study authors said: “Many patients and care givers lack awareness of the risks and benefits of ADHD drug treatment, leading to uncertainty in treatment decisions. This knowledge gap served as a key motivation for our research.
“Our study provides relevant information on additional benefits that are not captured in current randomised controlled trials,” they added.
“These findings are particularly important in informing the ongoing discussion about the inclusion of methylphenidate in the World Health Organization’s (WHO’s) model list of essential medicines.”
The WHO publishes a list of medicines it deems necessary to meet the population needs of all healthcare systems every two years, with the most recent list published in 2023.
In May 2025, an application was made to the WHO Expert Committee on Selection and Use of Essential Medicines to include methylphenidate on this list, previous applications having been rejected owing to factors such as “inconclusive” evidence on efficacy and “concerning” adverse effects.
Commenting on the study results, Henry Shelford, chief executive of ADHD UK, said: “This research gives clear indication of the cost to the individual and society of not diagnosing and treating ADHD effectively.
“You can’t access medication for ADHD without assessment from a specialist, but too often those assessments are locked behind multi-year NHS waits.
“The current NHS system also requires a new diagnosis every time you move. This is a waste of resources and creates an ADHD medication gap which, as this research highlights, might have a life-changing impact.
“We have woeful levels of under-diagnosis across the UK — around just 10% of those with ADHD currently have a diagnosis. And in too many areas the waiting time is going up rather than down. We need systemic change in the UK to prevent the outcomes and costs this research highlights,” he added.
In July 2025, the NHS Business Services Authority published data showing that the number of adults in England prescribed medication for ADHD had risen by almost one-quarter over 12 months.
The figures showed that 190,000 adults were prescribed central nervous system (CNS) stimulants and drugs for ADHD in 2024/2025, a 24% increase from 2023/2024.
