August 14, 2025: A new study conducted by researchers at the University of Southampton in the UK and the Karolinska Institute in Sweden has revealed some positive long-term benefits of ADHD (Attention-Deficit/Hyperactivity Disorder) medication. The research showed a significant drop in critical outcomes post medication, such as suicidal behaviour, substance misuse and vehicular accidents associated with ADHD.
This large-scale study utilized Swedish national registers to track 148,581 individuals aged 6 to 64 with a new ADHD diagnosis between 2007 and 2020. Among them, 84,282 (57%) started ADHD medication within three months of diagnosis. The study adopted a target trial emulation approach, aiming to replicate the design of a randomized controlled trial to analyse the effects of ADHD medication on five critical outcomes: suicidal behaviour, substance misuse, accidental injuries, transportation accidents, and criminality.
The results showed that ADHD medication was associated with reduced rates of first occurrences: a 17% decrease in suicidal behaviour, a 15% decrease in substance misuse, a 12% decrease in transportation accidents, and a 13% decrease in criminality.
Researchers speculate that these benefits may stem from the medication’s ability to reduce impulsivity, thereby decreasing aggressive behaviour and criminality, and to improve attention, minimizing distractions and lowering the risk of traffic accidents.
The study’s lead author, Dr. Samuele Cortese, highlighted that these findings are of significant importance from both public health and clinical perspectives. “They provide robust evidence that ADHD medication can reduce risks previously associated with untreated ADHD, such as job instability, anxiety, addiction, and other issues,” he said.
The study’s senior author, Dr. Zheng Chang, noted that this study is currently one of the most rigorous analyses of observational data, though it cannot entirely eliminate bias. The large sample size, use of national linked registers, and sophisticated design lend greater confidence to the results, suggesting that these findings are likely attributable to medication use rather than other factors.
The study also found that the benefits of medication were particularly pronounced in individuals with a history of frequent occurrences of these events, indicating that those with more severe symptoms may benefit the most. However, the study had certain limitations. For instance, it could not track whether participants actually took their medication as prescribed or assess the severity of ADHD symptoms. Consequently, it remains unclear whether the medication benefits apply to all individuals with ADHD or primarily to those with severe symptoms.
ADHD is a neurodevelopmental disorder characterized by symptoms such as inattention, hyperactivity, and impulsivity. It affects approximately 5% of children and 2.5% of adults globally.
Evidential support for positive outcomes in other studies
In recent years, the rising number of ADHD diagnoses has sparked debates about the possibility of “overdiagnosis.” This study offers additional evidence of the substantial value of ADHD treatment. Professor Adam Guastella of the University of Sydney stated that such benefits have been repeatedly shown in prior studies, but the large sample size, national registry data, and advanced analytical methods used in this study provide greater confidence in the results.
A study involving 26,249 men and 12,504 women showed that ADHD medication reduced the rate of substance abuse by 31%. The longer the medication was taken, the lower the risk, and the beneficial effects persisted even after discontinuation of the medication.
A study of 109,000 individuals indicated that ADHD is associated with a 240% increased risk of dementia later in life. However, this association was not observed in individuals who received ADHD medication treatment, suggesting that treatment may have long-term positive effects.
A study of over 25,000 individuals demonstrated that suicidal behaviour in ADHD patients increased immediately before starting methylphenidate treatment. Researchers suggested these attempts might have prompted the initial diagnosis and treatment. While the medication did not reduce the risk of self-harm in the first 90 days post-treatment, in the long term, it decreased suicidal behaviour to levels comparable to those without ADHD. A 2023 systematic review confirmed these trends, indicating that long-term pharmacological treatment reduces the risk of suicide in individuals with ADHD.
Common side effects and long-term risks of ADHD medications:
Stimulant medications: Common side effects include low or no appetite, weight loss, sleep problems, social withdrawal, and in some cases, increased activity or irritability as the medication wears off (rebound effect), tics, minor growth delays, etc. Long-term use may increase the risk of heart disease, high blood pressure, seizures, irregular heartbeats, abuse and addiction, and skin discolouration.
Non-stimulant medications: Side effects may include drowsiness, stomach pain, nausea, fatigue, and low blood pressure. Atomoxetine (Strattera), a non-stimulant ADHD medication, has been linked to seizures and irregular heartbeats. The FDA advises individuals with a history of these conditions to avoid it. The methylphenidate skin patch (Daytrana) has been associated with chemical leukoderma, a condition causing permanent skin pigmentation loss at the application site.
The findings of this study carry important implications for clinical practice. Cortese emphasized that when doctors discuss potential medication use with families, they often focus on the type of medication and its side effects but seldom address the risks of untreated ADHD. This study provides evidence that medication can reduce such risks. If left untreated, ADHD may lead to unfortunate consequences. While the side effects of ADHD medication should not be overlooked, the risks associated with untreated ADHD should also be communicated to patients. Only then can patients make informed decisions about their treatment.
