Attention-deficit/hyperactivity disorder (ADHD) is a well-established neurodevelopmental disorder recognized across the globe. An international consensus statement authored by leading ADHD experts from North America, Europe, Asia, and Australia provides 208 evidence-based conclusions about the nature, course, genetics, diagnosis, and treatment of ADHD. More than 350 experts from multiple continents reviewed the available evidence, enabling clinicians and researchers to make strong, meta-analytic statements about many aspects of the disorder, including the validity of the ADHD diagnosis across the lifespan, its multifactorial and polygenic etiology, the efficacy and safety of ADHD medications, its association with important somatic medical comorbidities (including cardiovascular and metabolic conditions), and many more (Faraone SV, et al 2021). While there is broad and strong scientific consensus about the disorder itself, how ADHD is diagnosed and treated varies significantly across the globe, often for reasons unrelated to biology or treatment efficacy.
How Health-Care Systems Influence ADHD Diagnosis and Treatment
Differences in countries’ healthcare systems often translate into very different patient experiences. For example, many European and public health systems operate specialist-led referral pathways that can involve longer waits for assessment but tend to offer stable, long-term treatment access once established (Asherson et al 2022, Fridman, et al. 2017). Similarly, in national health systems, medications are often covered or subsidized consistently, reducing financial barriers to continuity of care. In the United States, by contrast, some patients may get evaluation and can begin treatment more quickly, but insurance coverage, prior authorization, and frequent refills can prevent access or interrupt ongoing care (Hodgkin et al 2014, Shrestha et al, 2025, Hulkower RL et al, 2015, Staley BS et al, 2024). Studies from US have consistently demonstrated significant racial and ethnic disparity in ADHD diagnosis and treatment (Morgan, et al, 2013 and 2023).
When it comes to the adherence to ADHD medication, we often see adverse reactions, perceived lack of benefit, dosing burden, inconvenience and sometime stigma and attitude were often reported from countries with universal healthcare, such as those found from TIMESPAN study ART-CARMA (Barnes, et al 2026, Baweja R et al, 2021). While in US, insurance, cost, and administrative barriers play a unique and substantial role, frequently contributing to treatment gaps or discontinuation (Baweja R et al, 2021, Blake SC, et al 2019). It’s worth mentioning that barriers, restrictions and coverage denials even exist in a significant proportion of individuals with insurance in US. These system-level barriers in the U.S. are in addition to the clinical and personal reasons observed elsewhere, adding an additional layer of discontinuation risk that is specific to fragmented, insurance-based systems. Cross-country analyses, such as those conducted by TIMESPAN, not only reaffirm the universal scientific consensus on ADHD but also reveal fundamental differences in real-world outcomes driven by health-system structure. For example, one of our cross-country analyses found that the United States had among the shortest time to first medication discontinuation and the highest rates of treatment discontinuation (Brikell I, et al 2023).
So, what does all of this mean for people living with ADHD around the world—and for the clinicians and researchers who care for them? It means that long-term outcomes depend on far more than symptoms and biology, or whether a medication works in theory. They also depend on practical realities: insurance coverage, how easy it is to see a specialist, how prescriptions are regulated, and many other features of the health-care system and broader society. These factors vary widely from country to country. As a result, two people with the same condition and similar needs can have very different experiences simply because of where they live. Differences in access and continuity of care can also compound over time, shaping not only ADHD-related outcomes but overall health and well-being. Recognizing this helps us see that health outcomes are shaped not only by biology, but also by health systems and public policy—and it highlights why international research and collaboration are essential to improving care for everyone with ADHD.
This post was written by Yanli Zhang-James & Stephen V Faraone.