Understanding ADHD
What is ADHD?
With ADHD, attention, activity and impulses are regulated differently than in most people. It starts in childhood and, for many people, lasts a lifetime.
ADHD stands for Attention Deficit Hyperactivity Disorder.
Three core features
Attention deficit
Easily distracted, difficulty starting or finishing things, forgetting or losing things.
Hyperactivity
In children, often visibly overactive. In adults, more often an inner restlessness and difficulty relaxing.
Impulsivity
Act first, think later. Interrupting others, quick decisions, difficulty waiting.
Three types of ADHD
- CombinedFeatures of attention deficit as well as of hyperactivity and impulsivity. The most common form.
- Predominantly inattentiveMainly features of attention deficit. Also known as ADD.
- Predominantly hyperactive-impulsiveMainly features of hyperactivity and impulsivity. The least common form.
What happens in the brain
It mainly concerns the prefrontal cortex: the part at the front of the brain that helps with planning, sustaining attention and holding back impulses. There, nerve cells pass signals to each other using the substances dopamine and noradrenaline.
The most widely used explanation is that in ADHD, less of these substances is available between the cells. The signal then gets through less well. So ADHD is not a matter of not wanting to, or of upbringing.
Enough dopamine and noradrenaline between the cells. The next cell is properly activated and passes the signal on.
What does that mean?
The prefrontal cortex works as a control centre. It filters what is important, keeps your attention on a task and holds back an impulse. You can also start and finish a boring task.
Less of these substances between the cells. Fewer receptors are reached and the next cell is less activated.
What does that mean?
The control centre receives too little. As a result, more stimuli actually come in unfiltered, attention jumps to whatever is new or exciting, and an impulse is held back less well. A boring task takes a lot of effort. Something that interests you does work, sometimes with hyperfocus.
- Dopamine and noradrenaline
- Receptor on the next cell
- Small pump that takes the substance back up
A simplified drawing. In reality it involves networks of brain areas, and it differs from person to person.
Medication makes dopamine and noradrenaline stay available for longer. That is why it helps many adults with ADHD. More about medication
What causes it?
ADHD is largely hereditary: 70 to 80 per cent of the differences between people are due to genetic predisposition. Usually several factors play a role together, such as predisposition and circumstances around birth, for example premature birth.
If a parent, brother or sister has ADHD, the chance of ADHD is considerably higher.
How common is it?
- Adults in the Netherlands
- 3.2%Have ADHD, according to national research by the Dutch Trimbos Institute (2019–2022).
- Children
- 3–5%Are estimated to have ADHD.
- As adults
- 2 in 3Of children with ADHD still have symptoms later in life.
Myths and facts
How the diagnosis is made
Questions about ADHD
- ADD is an older name for the type of ADHD in which mainly attention problems play a role. Today this is called ADHD, predominantly inattentive presentation.
- Largely, yes. 70 to 80 per cent of the differences between people are due to genetic predisposition. If a parent, brother or sister has ADHD, the chance of ADHD is higher.
Sources
- JGZ guideline ADHD (youth health care) – diagnosis according to the DSM-5 (in Dutch) (opens in a new window)
- Guideline on ADHD in adults (NVvP, Dutch Psychiatric Association) (in Dutch) (opens in a new window)
- NHG guideline (Dutch College of General Practitioners) – ADHD in children (in Dutch) (opens in a new window)
- Thuisarts – ADHD in adults (in Dutch) (opens in a new window)
- Trimbos / VZinfo – ADHD in the population (NEMESIS-3) (in Dutch) (opens in a new window)
- Kooij et al. (2019) – European consensus statement on ADHD in adults (opens in a new window)
- Faraone et al. (2021) – World Federation of ADHD, international consensus statement (opens in a new window)
- Wolraich et al. (1995) – Sugar and behaviour in children, JAMA (opens in a new window)
- Impuls & Woortblind – Characteristics of ADHD (in Dutch) (opens in a new window)
Checked in October 2026.
Understanding ADHD
Read more
- ADHD in adultsWhat ADHD looks like in adults: inner restlessness, planning and organising, emotions. Why it is often only discovered late, and how common it is.
- ADHD in childrenFor parents: how ADHD shows itself in children, where you can go (youth health doctor, neighbourhood team, GP), what you can do at home and what changes at 18.
- ADHD in womenWhy ADHD in girls and women is often recognised later: the inattentive type, adapting and compensating, and the role of hormones.
Do you recognise yourself in this?
The self-test gives you a first impression in about five minutes. It is not a diagnosis; discuss the result with your GP.