Attention-deficit/hyperactivity disorder (ADHD) is a common childhood disorder that can continue through adolescence and adulthood. Symptoms include higher than normal levels of impulsivity and inattention that prevent an individual from functioning properly in various settings like school or work. 

GlobalData epidemiologists found that the US has a significantly higher diagnosed prevalence of ADHD compared with the 5EU (France, Germany, Italy, Spain, UK) and Japan, though it is unclear if this is a reflection of a truly higher disease burden or of overdiagnosis and treatment.

ADHD is known as an American disorder because of the high prevalence and number of cases in this country. In 2014, the ADHD prevalence in the US for ages 3 years and older was 6.91%, while the 5EU combined and Japan only had prevalence estimates of 1.23% and 1.21%, respectively (Figure 1). Additionally, the number of cases of ADHD in the US accounted for 80.0% of all ADHD cases in the 7MM (US, 5EU, and Japan) in 2014. We expect this pattern to continue into the next decade, with the number of cases in the US accounting for 84.5% of ADHD cases in the 7MM in 2024 (Figure 2).

It is difficult to determine why ADHD prevalence in the US is so much higher. The difference has been attributed to differences in the epidemiology studies’ methodology, diagnostic criteria, and case identification. Others believe ADHD is over-diagnosed in the US, or at least there is a perception of over-diagnosis due to overmedication, dramatic media coverage, and anecdotal personal experiences. GlobalData epidemiologists also suggest that social acceptance of mental illness may contribute to the higher prevalence of ADHD observed in the US, as it is documented that in some countries, such as Japan, negative perceptions of mental illnesses are roadblocks to disease awareness and diagnosis.