Here for a quick answer? It's the first thing on this page. Everything after it is the fuller picture — definition, presentations, symptoms, criteria, key numbers and common myths, all in one place.
ADHD stands for Attention-Deficit/Hyperactivity Disorder.
It's a neurodevelopmental condition — a difference in how the brain develops and regulates itself — marked by a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with everyday functioning. It begins in childhood, it's highly heritable, and it often continues into adult life.
One important nuance the name gets wrong: ADHD isn't really a deficit of attention. People with ADHD can focus intensely — sometimes for hours — on things that genuinely interest them. The difficulty is directing attention on demand, toward whatever is objectively important rather than whatever is currently interesting or urgent. It's a regulation problem, not a quantity problem.
ADHD is a condition rooted in the development and wiring of the brain, particularly the networks that manage executive function — the mental control system that handles starting tasks, holding information in mind, planning ahead, resisting impulses, switching between activities and regulating emotion. Differences in dopamine and norepinephrine signalling mean these systems don't come online as reliably or on demand.
Because of that, ADHD shows up far beyond "not paying attention." It touches time perception, motivation, emotional intensity, memory for things that aren't in front of you, and the ability to start something boring even when you badly want to. It's recognised as a disorder in both major diagnostic systems — the American Psychiatric Association's DSM-5 (current edition the DSM-5-TR, 2022, which left the ADHD criteria unchanged) and the World Health Organization's ICD-11.
The quiet one. Drifting focus, disorganisation, forgetfulness, losing things, missing details. Often missed entirely in childhood — especially in girls — because it disrupts nobody but the person living it. This is what used to be called "ADD."
The visible one. Restlessness, fidgeting, feeling driven by a motor, talking over people, blurting, acting before thinking. Most likely to be spotted early because it's disruptive in a classroom. Least common of the three on its own.
Meaningful symptoms of both. This is the most commonly diagnosed presentation.
They're called presentations, not types, on purpose — which one fits a person can change across their life. A hyperactive child often becomes an adult whose hyperactivity has turned inward into restlessness and racing thoughts.
Described in everyday language rather than clinical wording. Everyone does some of these sometimes — what matters for ADHD is the pattern: frequent, long-running, and genuinely getting in the way.
Several of ADHD's most life-shaping features aren't in the official symptom list: rejection sensitivity, time blindness, hyperfocus, task paralysis, emotional dysregulation, and out-of-sight-out-of-mind forgetting. Many people find these describe their experience better than the criteria do.
Diagnosis is a clinical judgement made by a qualified professional — there's no blood test or brain scan for it. In broad terms, the DSM-5 asks for all of the following:
| Requirement | In practice |
|---|---|
| Enough symptoms | At least 6 from a category for children up to 16; at least 5 for those 17 and older, reflecting how symptoms soften with age |
| Long enough | Present for at least 6 months, to a degree out of step with the person's developmental level |
| Early enough | Several symptoms present before age 12 — even if nobody recognised them at the time |
| Broad enough | Showing up in two or more settings — home, school, work, social life |
| Impactful enough | Clear evidence they interfere with social, academic or working life |
| Not better explained | Other conditions that could account for the picture have been considered and ruled out |
Severity is also noted as mild, moderate or severe. A proper evaluation typically includes a clinical interview, standardised rating scales, developmental and school history, and where possible input from someone who knows you well. What an assessment involves →
| Figure | What it means | Source |
|---|---|---|
| 11.4% | US children aged 3–17 ever diagnosed — about 7.1 million, or roughly 1 in 9 | CDC / NSCH 2022 |
| 6.0% | US adults with a current diagnosis — about 15.5 million | CDC 2023 |
| 55.9% | Of those adults, more than half (55.9%) weren't diagnosed until age 18 or older | CDC 2023 |
| ~74% | Heritability — among the most heritable of psychiatric conditions | Faraone & Larsson, 2019 |
| 15% vs 8% | Boys diagnosed roughly twice as often as girls in childhood | CDC / NSCH 2022 |
| ~78% | Of children with ADHD have at least one co-occurring condition | CDC / NSCH 2022 |
| ~30% | Of US children with ADHD received neither medication nor behaviour treatment | CDC / NSCH 2022 |
| ~5–7% | Estimated global prevalence in children; roughly 2.5–4% in adults | International meta-analyses |
Figures reflect diagnosed prevalence in national surveys, which is not the same as true underlying prevalence — under-diagnosis and over-diagnosis both occur, and rates vary by country and method. Full statistics →
ADD (Attention Deficit Disorder) is an obsolete term. It was replaced in 1994, when the diagnostic manual folded everything under the single name ADHD with subtypes. So what people mean by "ADD" — inattentive, not hyperactive — is now formally called ADHD, predominantly inattentive presentation. You'll still hear ADD in everyday speech, and there's nothing wrong with that; it's just not the clinical term.
Elsewhere you may meet hyperkinetic disorder, the older ICD term, and AuDHD, an informal community word for co-occurring autism and ADHD. Full glossary of ADHD terms →
There's no cure, but ADHD responds well to support. Care is usually layered rather than single-track, and what works is individual — decisions belong with you and a qualified clinician.
Prescribed and monitored by a clinician, with stimulant and non-stimulant options. Effects, suitability and trade-offs are a conversation to have with your doctor. More →
CBT adapted for ADHD, ADHD coaching, parent training for children, and support for the shame and self-esteem that often accompany a late diagnosis.
External systems that carry what working memory won't — visible reminders, body doubling, shrinking tasks, sleep and movement. The toolkit →
ADHD stands for Attention-Deficit/Hyperactivity Disorder — a neurodevelopmental condition involving a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development.
A brain-based developmental condition that makes it harder to regulate attention, impulses and activity level. It isn't a shortage of attention so much as difficulty directing it on demand — the ADHD brain runs on interest and urgency rather than importance.
ADD is an outdated term. Since 1994 the official name has been ADHD, covering all presentations including those without hyperactivity. What people call ADD is now described as ADHD, predominantly inattentive presentation.
Predominantly inattentive, predominantly hyperactive-impulsive, and combined. They're called presentations rather than types because which one fits a person can change across their lifetime.
Yes. It's a recognised neurodevelopmental disorder in both the DSM-5 and the ICD-11, and one of the most extensively researched conditions in mental health. Twin studies place its heritability at roughly 74%.
In the US, about 11.4% of children aged 3–17 (around 7.1 million, or 1 in 9) have ever been diagnosed according to 2022 CDC survey data, and about 6.0% of adults (15.5 million) have a current diagnosis. Global estimates sit around 5–7% of children.
No. ADHD is a lifelong neurodevelopmental difference, though symptoms often change with age. Treatment and support can substantially reduce its impact on daily life.
Only a qualified professional can tell you. If the patterns here have followed you since childhood, show up in more than one part of your life, and genuinely get in the way, that's worth raising with a doctor. This site deliberately doesn't offer a self-diagnosis quiz — see how assessment works instead.
A structured path through everything on this site, from first principles to daily life — with your progress saved.
An interactive simulation of the difference between a neurotypical and an ADHD experience of the same moment.
What to do first, what to expect, and how to be kind to yourself while it all lands.
