ADHD is one of the most common neurodevelopmental conditions in the world. Globally, about 7.6% of children under 12 and 5.6% of teenagers meet the criteria for it. In the United States, where screening and diagnosis rates are higher than most countries, roughly 1 in 9 children have received an ADHD diagnosis. Among adults, an estimated 15.5 million Americans (6%) currently have one.
How Many Children Have ADHD
The CDC’s most recent data, from 2022, puts the number at about 7 million U.S. children ages 3 to 17 with a diagnosis, or 11.4% of all kids in that age range. That’s roughly one million more children than were diagnosed in 2016. About 6 in 10 of those children have moderate or severe symptoms.
Globally, the numbers are somewhat lower, partly because many countries have less access to mental health screening. A large meta-analysis covering dozens of studies found that 7.6% of children under 12 and 5.6% of adolescents ages 12 to 18 met diagnostic criteria. Prevalence estimates tend to be highest in North America and the Middle East, and lowest in African and Asian countries, though differences in how studies are conducted make direct comparisons tricky.
ADHD in Adults
ADHD doesn’t disappear at 18. Worldwide, an estimated 2% to 5% of adults experience ongoing symptoms of inattention, hyperactivity, or impulsivity. In the U.S., the figure is closer to 6%, with about 15.5 million adults reporting a current diagnosis as of 2023.
What’s striking is that more than half of those adults (nearly 56%) weren’t diagnosed until adulthood. Many spent years struggling with focus, organization, or emotional regulation before anyone identified ADHD as the cause. This is especially true for women, who are frequently treated for anxiety or depression before ADHD is even considered. Over 44% of adults with ADHD carry at least one additional mental health diagnosis, most commonly anxiety (25%) or depression (about 19%).
Boys Are Diagnosed Far More Often Than Girls
In childhood, boys are diagnosed at nearly twice the rate of girls: 15% compared to 8%. The ratio works out to roughly 3 boys for every 1 girl. But by adulthood, that gap essentially closes to about 1:1, which strongly suggests that many girls are being missed during childhood rather than simply not having the condition.
Girls with ADHD are more likely to present with inattentive symptoms (difficulty concentrating, forgetfulness, disorganization) rather than the hyperactive, disruptive behavior that tends to get flagged in classrooms. Research shows that girls have more visits to psychiatric care before receiving an ADHD diagnosis, are more likely to be prescribed antidepressants first, and are older than boys at the time of both referral and diagnosis. Women and girls continue to be underrecognized, and that delay can mean years of struggling without the right support.
Diagnosis Rates Are Climbing
ADHD diagnoses in the U.S. rose from 6.1% to 10.2% over the two decades between 1997 and 2016, and have continued climbing since. The increase has been especially sharp among girls, whose diagnosis rates tripled over that same period, growing three times faster than boys’ rates.
Whether this reflects a true increase in ADHD or simply better recognition is an ongoing debate. Several factors point toward improved detection rather than a new epidemic. Diagnostic criteria were updated in 2013, and the changes made it easier to identify ADHD in older teens and adults. The minimum number of symptoms required for diagnosis in people 17 and older was lowered from six to five. The age by which symptoms needed to appear was pushed from 7 to 12. The definition of impairment was loosened from “clinically significant” problems to symptoms that “reduce the quality” of daily functioning. Autism spectrum disorder was also removed as an exclusionary diagnosis, meaning people with both conditions can now receive both diagnoses.
Greater public awareness plays a role too. Parents, teachers, and adults themselves are more familiar with what ADHD looks like, particularly the inattentive type that was historically overlooked. Social media has also driven many adults to seek evaluation after recognizing symptoms in themselves.
Race and Income Affect Who Gets Diagnosed
Diagnosis rates vary meaningfully by race and ethnicity. In the U.S., Black and white children are diagnosed at the highest rates (both around 12%), while Asian children have the lowest rate (4%). American Indian and Alaska Native children fall at about 10%, and Hispanic children (10%) are diagnosed somewhat less often than non-Hispanic children (12%).
Income matters too, and in a way that might surprise people. ADHD was long thought to affect all social classes equally, but the evidence consistently shows it’s more common in lower-income families. Children from households earning under $20,000 a year are about four times as likely to meet criteria for ADHD compared to children from families earning $50,000 or more. The relationship between poverty and ADHD is complex. Chronic stress, less access to prenatal care, environmental exposures, and other factors associated with poverty may all contribute. Interestingly, when a parent also has ADHD, family income makes little difference: between 32% and 42% of those children meet criteria for the condition regardless of how much the family earns. The income gap is widest among families where neither parent has a history of ADHD, suggesting that environmental stressors tied to poverty play a significant role on their own.
What “Common” Really Means
To put the numbers in perspective, ADHD is more prevalent than epilepsy, type 1 diabetes, or autism in children. In a typical U.S. classroom of 25 students, two or three will have a diagnosis. Among adults, the 6% prevalence means you almost certainly know multiple people living with it, whether or not they’ve been formally identified. Given that diagnostic criteria have broadened, awareness has grown, and girls and women are finally being recognized at higher rates, the number of people with a documented ADHD diagnosis will likely keep rising for some time.