Attention deficit hyperactivity disorder medication is linked to significantly lower risk of suicidal behaviours, substance misuse, transport accidents and criminality, according to a study of the wider outcomes of treatment.
The research, based on the medical records of nearly 150,000 people in Sweden, suggested that the drugs could have meaningful benefits beyond helping with the core symptoms of ADHD.
Although the study was not a randomised trial – and so cannot definitively prove that medication caused improved outcomes – it adds to evidence of the substantial value of treatment.
“We found that ADHD medication was associated with significantly reduced rates of first occurrences of suicidal behaviours, substance misuse, transport accidents and criminality,” said Prof Samuele Cortese, a child and adolescent psychiatrist and researcher at the University of Southampton. “Our results should inform the debate on the effects and safety of ADHD medications.”
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 investigated: a 17% reduction for suicidal behaviour, 15% for substance misuse, 12% for transport accidents and 13% for criminality.
It is well established that ADHD, thought to affect about 5% of children and 2.5% of adults worldwide, is linked to higher rates of mental health problems including suicide, substance misuse and accidental injuries. People with ADHD are also disproportionately represented within the criminal justice system.
Randomised clinical trials have demonstrated that for many patients, medication can help alleviate hyperactivity, impulsivity and the inattention. But there has been more limited evidence on whether these improvements translate into benefits in everyday life, at a time when the increasing number of people being diagnosed has fuelled a debate about the possibility of “overdiagnosis”.
The number of prescriptions being issued in England for attention deficit hyperactivity disorder (ADHD) medication has risen by 18% year on year since the pandemic.
The latest study, which the researchers say is the largest and most rigorous of its kind, used Swedish national registers from 2007 to 2020 to examine the effects of ADHD drug treatment in 148,581 individuals aged six to 64 years with a new diagnosis of ADHD.
The team used a technique called target trial emulation, which aims to apply the design principles of a clinical trial to existing medical records through the use of strict inclusion criteria, follow-up timeframes and the use of statistical techniques to compensate for the fact that people were not randomly assigned to “treatment” or “placebo” arms.
Dr Zheng Chang, an epidemiologist at the Karolinska Institute in Stockholm and senior author of the research, said: “It’s now considered one of the most rigorous methods for analysing observational data. However, since we don’t have the real randomisation data it is not bias-proof.”
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Of the 148,581 individuals with ADHD (average age 17 years, 41% female), 84,282 (57%) started drug treatment for ADHD, with methylphenidate being the most common.
After adjusting for potential confounding factors, those who took medication had a reduced risk of first occurrence of suicidal behaviour, substance misuse, transport accidents and criminality, although there was no significant risk reduction for a first occurrence of accidental injury. Among people with recurrent events, there were statistically significant reductions linked to all five outcomes, the paper in the British Medical Journal reports.
“When clinicians discuss the possible use of medication with families, oftentimes there is not a focus on what are the risks if you don’t treat,” said Cortese. “If left untreated, there will be unfortunately some risk. Now we have evidence that medication can reduce this risk.”
Prof Adam Guastella, of the Children’s Hospital Westmead Clinical School at the University of Sydney, said: “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 findings aren’t explained by something else other than medication use.
“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. 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.”
