ADHD medication reduces risk of suicide and criminal behaviour

Drug treatment for people with newly diagnosed attention deficit hyperactivity disorder (ADHD) has a beneficial effect in reducing the risks of suicidal behaviours, substance misuse, accidental injuries, transport accidents, and criminality, according to new research.

The study published in the BMJ found that the risk reductions were more pronounced for recurrent events, suggesting that the findings should help inform clinical practice and the debate on ADHD drug treatment.

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.

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• ADHD: how to restore confidence in the diagnosis

The researchers say this is the first study of its kind to show the beneficial effects of ADHD drug treatment, and the impact may be explained by reductions in impulsivity and improvements in attention and executive functions, in line with findings from randomised controlled trials.

For instance, reduced impulsivity may lower criminality by curbing aggressive behaviour, whereas enhanced attention may decrease the risk of transport accidents by minimising distractions. These findings are consistent with those of previous observational studies using within-individual designs.

Representative of ADHD patients in routine clinical settings

The researchers drew on data from Swedish national registers (2007-2020) to examine the effects of ADHD drug treatment in 148,581 individuals aged 6-64 years with a new diagnosis

Using a technique called target trial emulation, which applies the design principles of randomised trials to observational data, they assessed first and recurrent events for five outcomes (suicidal behaviours, substance misuse, accidental injuries, transport accidents, and criminality) over two years after diagnosis.

Of the 148,581 individuals with ADHD (average age 17 years; 41% female), 84,282 (57%) started drug treatment, with methylphenidate being the most commonly prescribed (88.4%).

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, amongst 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.

As this was a large study based on national registry data, and findings were similar after further sensitivity analysis, the researchers say this provides evidence that is representative of patients in routine clinical settings.

Alison Bloomer

Alison Bloomer is Editor of Learning Disability Today.

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