ADHD drug treatment helps prevent suicidal behaviours, substance misuse, accidents

Drug treatment for attention deficit/hyperactivity disorder (ADHD) may reduce the first occurrence rates of suicidal behaviours, substance misuse, transport accidents, and criminality, but not accidental injuries, suggest the results of a target trial emulation.

Moreover, ADHD drug treatment is associated with reduced rates of recurrent events for all these outcomes, including accidental injuries.

“The observed reduced rates were more pronounced among patients with a history of outcome events and for stimulants vs nonstimulants,” the investigators said.

A total of 148,581 individuals with ADHD (median age 17.4 years, 41.3 percent female) were included in the analysis. Of these, 84,282 (56.7 percent) initiated drug treatment, with methylphenidate being the most common (n=74,515, 88.4 percent). [BMJ 2025;390:e083658]

Drug treatment for ADHD, compared with noninitiation, showed a significant correlation with a lower rate of the first occurrence of suicidal behaviours (weighted incidence rates [WIR], 14.5 per 1,000 person-years in the initiation group vs 16.9 in the noninitiation group; adjusted incidence rate ratio [IRR], 0.83, 95 percent confidence interval [CI], 0.78‒0.88).

ADHD drug treatment was also associated with reduced first occurrence rates of substance misuse (WIR, 58.7 vs 69.1 per 1,000 person-years; adjusted IRR, 0.85, 95 percent CI, 0.83‒0.87), transport accidents (WIR, 24.0 vs 27.5 per 1,000 person-years; adjusted IRR, 0.88, 95 percent CI, 0.82‒0.94), and criminality (WIR, 65.1 vs 76.1 per 1,000 person-years; adjusted IRR, 0.87, 0.83‒0.90).

On the other hand, the reduction seen for accidental injuries did not reach statistical significance (WIR, 88.5 vs 90.1 per 1,000 person-years; adjusted IRR, 0.98, 95 percent CI, 0.96‒1.01).

Notably, the reduced rates were more noticeable among participants with previous events, with IRRs ranging from 0.79 (95 percent CI, 0.72‒0.86) for suicidal behaviours to 0.97 (95 percent CI, 0.93‒1.00) for accidental injuries.

For recurrent events, ADHD drug treatment resulted in reduced rates of suicidal behaviours (IRR, 0.85, 95 percent CI, 0.77‒0.93), substance misuse (IRR, 0.75, 95 percent CI, 0.72‒0.78), transport accidents (IRR, 0.84, 95 percent CI, 0.76‒0.91), criminality (IRR, 0.75, 95 percent CI, 0.71‒0.79), and even accidental injuries (IRR, 0.96, 95 percent CI, 0.92‒0.99).

“These results provide evidence on the effects of ADHD drug treatment on important health-related and social outcomes that should inform clinical practice and the debate on the drug treatment of ADHD,” the investigators said.

Mechanism

The benefits provided by drug treatment for ADHD may be attributed to the decreases in impulsivity and improvements in attention and executive functions, consistent with the results of previous randomized controlled trials. [N Engl J Med 2020;383:1050-1056; Neurosci Biobehav Rev 2024;162:105703]

“For instance, reduced impulsivity may lower criminality by curbing aggressive behaviour, whereas enhanced attention may decrease the risk of transport accidents by minimizing distractions,” the investigators said.

“These findings are consistent with those of previous observational studies using within-individual designs,” they added. [BMJ 2014;348:g3769; Biol Psychiatry 2020;88:452-458; J Child Psychol Psychiatry 2014;55:878-885; JAMA Psychiatry 2014;71:319-325]

The current emulation of target trials was conducted via linkage of national registers in Sweden (2007‒2020). Individuals aged 6‒64 years with a new diagnosis of ADHD, who either started or did not start drug treatment within 3 months of diagnosis were included.