A large Swedish study links prompt treatment to broad life benefits beyond symptom relief.
Starting drug treatment soon after an ADHD diagnosis is associated with significant reductions in suicidal behaviours, substance misuse, transport accidents and criminality, a large Swedish study has found.
The target trial emulation, published in The BMJ this week, linked national registers covering 148,581 individuals aged 6–64 years diagnosed with ADHD between 2007 and 2020.
More than half (56.7%) initiated medication within three months, most commonly methylphenidate (88.4% of initiators).
After accounting for factors including age, sex, education level, psychiatric diagnoses and medical history, ADHD medication was associated with reduced rates of a first occurrence of four of the five outcomes: a 17% reduction for suicidal behaviour, 15% for substance misuse, 12% for transport accidents and 13% for criminality.
The reduction was not statistically significant for a first-time accidental injury (88.5 v 90 per 1000 person years).
However, among people with recurrent events, the rate reductions associated with ADHD medication were seen for all five outcomes: a 15% reduction for suicidal attempts, 25% for substance misuse, 4% for accidental injuries, 16% for transport accidents and 25% for criminality.
The authors said this was the first study of its kind to show beneficial effects of ADHD drug treatment on broader clinical outcomes for all patients, and its findings highlighted its potential preventive role in high-risk populations.
ADHD affects around 5% of children and 2.5% of adults worldwide and is associated with adverse outcomes including suicidal behaviours, substance misuse, accidental injuries, transport accidents and criminality.
Although randomised trials have shown that ADHD medication alleviates core symptoms, evidence of its effects on these broader clinical outcomes are more limited.
The authors noted possible explanations include reduced impulsivity, which might lower criminality by curbing aggressive behaviour, and enhanced attention, which might decrease the risk of transport accidents by minimising distractions, suggest the authors.
They acknowledge several limitations, such as being unable to assess data on non-drug treatments or the impact of drug dosage. And while target trial emulation is one of the most rigorous approaches for analysing observational data, they couldn’t rule out the possibility that other factors, such as ADHD severity, genetic predispositions and lifestyle factors, may have affected their results, so no definitive causal conclusions could be drawn.
“Overall, our study provides relevant information on additional benefits that are not captured in current randomised controlled trials, offering valuable insights for patients, clinicians, guideline developers and other stakeholders weighing the benefits and risks of treatment,” they wrote.
“For instance, these findings are particularly important in informing the ongoing discussion about the inclusion of methylphenidate in the World Health Organization’s model list of essential medicines.”
Australian experts have responded to the study’s findings with great interest.
Professor Adam Guastella, Michael Crouch Chair in Child and Youth Mental Health in the Clinic for Autism and Neurodevelopment research from the Brain and Mind Centre and the Children’s Hospital Westmead Clinical School at The University of Sydney, said it was important to understand the risks and benefits of ADHD medication use, to give people informed choices about what they use to support themselves or their children.
“People can spend a long time seeking a diagnosis and discussing treatment, and the investment of time needs to be worth it and evidence-based. So it’s important to understand the breadth of possible impact,” he said.
“It’s always helpful to know if medications can impact daily life beyond reducing symptoms. This information is also important for government, to help policymakers understand the potential benefits of treatment for broader society, such as mental health or criminal outcomes.
“This study shows that individuals who started ADHD medication showed a reduction in suicidality, substance misuse and criminality. Such benefits have been shown repeatedly in previous studies, but the large sample size, use of a national registry, and more sophisticated analysis give greater confidence in these results that the findings aren’t explained by something other than medication use.”
Professor Guastella said this was one of a number of studies that showed the benefits of stimulant medication for people with ADHD, but warned this was not the case for everyone.
“People should know that if ADHD medications work for them and their child, that there will likely be many other positive impacts on life from treatment,” he said.
“Such effects will not work for everyone and there is still a need to understand why many individuals benefit from ADHD medication and some do not.
“Finally, even though the study was rigorous in its design, one cannot rule out that other unaccounted factors could be associated with these effects and the study focused on adults.”
Dr Stephen Bright, a senior lecturer (Addiction) at Edith Cowan University, said the research provided “further evidence that stimulant medication treatments for ADHD can be life-changing, reducing the risk of individuals experiencing a motor vehicle accident and drug-related harms, in addition to reducing the likelihood that they will engage in criminal behaviour and suicide”.
“Yet it is very difficult for many Australians to access a paediatrician or psychiatrist who is able to commence stimulant medication treatments where appropriate due to extensive waitlists, in addition to financial and regulatory obstacles,” he said.
“As such, a number of people with undiagnosed ADHD continue to present for help with their drug use at alcohol and other drug treatment services, while others remain in prison.
“While there are concerns about the over-prescribing of stimulant medications in Australia and the potential diversion of stimulant medications for non-medical use, it is important that we find the right balance between protecting the community from diverted medications and the right of people with ADHD to access a gold standard treatment so that they are able to thrive and be productive members of society.”
Professor Stuart Kinner, head of the Justice Health Group at Curtin University and Murdoch Children’s Research Institute, described it as a “landmark piece of research, convincingly demonstrating the diffuse benefits of ADHD diagnosis and treatment”.
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“Timely drug treatment led to significant reductions in suicidal behaviour, substance use, transport accidents and criminality,” he said.
“These findings confirm what many already know: failure to diagnose and treat ADHD can lead to self-medication with alcohol or other drugs, poor mental health, injury and incarceration.
“Too many people with undiagnosed ADHD end up in the criminal justice system, where their condition may remain undiagnosed and untreated. It is estimated that around one in four people in prisons and youth detention centres have ADHD, although this is frequently undiagnosed.”
Professor Kinner said the research supported greater investment in ADHD screening for children and adolescents in schools, which could reduce the number of young people who end up self-medicating their ADHD with substances, and living lives distinguished by “poor mental health, injury and – far too often – criminalisation of neurodivergence”.
It should also support ADHD screening for people who end up in the criminal justice system, leading to better health outcomes for those diagnosed and treated, and potentially reduce rates of reoffending.
“That’s a win for public health, and a win for public safety,” said Professor Kinner.
