ADHD stands for attention deficit/hyperactivity disorder. It's thought to be caused by developmental differences in the brain that affects the parts controlling attention, concentration, impulsivity, activity levels and memory.

This means a child's behaviour can be anything from being 'very dreamy' (or unable to pay attention) through to being 'always on the go' (or hyperactive).

A person with ADHD has difficulty filtering out all the information coming into his brain, so he's easily distracted, tends to respond before he has considered things properly and doesn't know when to stop.

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A child with ADHD will take longer to settle and concentrate than a child without, and may have problems following instructions.

Children with ADHD may have above-average intelligence but find it hard to learn. They often also have problems socialising.

The condition is long term and can continue through adult life. There is a genetic component, and children with ADHD often have relatives with ADHD.

ADHD isn't caused by bad parenting, but a child's surroundings and support can affect how severe the symptoms are and how well he can learn to deal with them.

Different names for ADHD

ADHD was first described by George Still in 1902. He called it 'morbid defect of moral control'. It's also been called:

  • minimal brain damage (1930).
  • minimal brain dysfunction (1960).
  • hyperkinetic reaction of childhood (1968).
  • attention deficit disorder (ADD) with or without hyperactivity (1980).

Since 1987, it has been known as ADHD or attention deficit hyperactivity disorder. The World Health Organisation brought out a second definition in 1992, 'hyperkinetic disorder', a narrower definition than ADHD that includes more serious cases.

Different ways of classifying ADHD

A doctor diagnoses ADHD by looking at your child's symptoms. There are two different ways to assess symptoms.


The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (known as DSM-5) classifies ADHD in three ways, based on the child's current behaviour.

The symptoms are split into two categories: inattention and hyperactivity-impulsivity. A doctor will look at how many symptoms your child has in each category.

  • ADHD combined presentation: this is the most common type, and means the child has six or more symptoms in each category.
  • ADHD predominantly inattentive presentation: this means the child has six or more inattention symptoms but fewer than six hyperactivity-impulsivity symptoms.
  • ADHD predominantly hyperactive-impulsive presentation: this is the least common type and means that the child has six or more hyperactivity-impulsivity symptoms but fewer than six inattention symptoms

It is important to recognise that children may switch between the different presentations over time.


The World Health Organisation International Classification of Diseases, 10th Revision 1992 (known as ICD-10) has a similar list of symptoms for 'hyperkinetic disorder'.

To be diagnosed with hyperkinetic disorder, your child must have:

  • at least 6 out of 9 symptoms of inattention
  • and 3 out of 5 symptoms of hyperactivity
  • and 1 out of 4 symptoms of impulsivity.

What are the symptoms?

There are three core symptom groups for ADHD:

  • hyperactivity
  • impulsivity
  • inattention.

There is a list of different behaviours within these groups.

To get a diagnosis of ADHD under either ICD-10 or DSM-IV-TR, symptoms must:

  • have been present for at least six months
  • have developed before the age of seven (ICD-10) or twelve (DSM-5).
  • have a significant negative impact in at least two settings, for example at home, work, school. Sometimes parents don't feel there's a problem at home, either because they don't have other children to compare the ADHD child to, or because they've adjusted to their child's behaviour and are handling it well.

Your child must also not have another disorder, eg mood, anxiety or personality, which could cause the same symptoms.

In general, boys tend to show more symptoms of hyperactivity and girls tend to show more symptoms of inattention.

In adults, symptoms are very similar but the hyperactivity tends to become a feeling of restlessness, fidgeting, difficulty in relaxing or feeling 'on edge' all the time.

What causes ADHD?

Experts believe ADHD is partly due to areas of the brain that affect behaviour not developing as they should and as a consequence leading to an imbalance of chemicals that transmit messages to the brain.

The main factors are:

  • the child's temperament, which affects attitude and personality.
  • a genetic link – recent studies show that 70 to 80 per cent of the risk for ADHD is genetic. This is why ADHD tends to run in families.
  • subtle insults to the brain, either pre-birth or due to trauma during birth (this is a small percentage of cases) that result in the brain developing differently.

Certain aspects of the family environment are found more often in children with ADHD, eg family stress. It isn't clear if these factors can cause ADHD. They may just increase the likelihood that ADHD will develop in a child who is already genetically prone to it.

ADHD is not caused by:

  • poor parenting. Parenting styles can affect your child's behaviour though and, in turn, can affect your ability to manage difficult behaviour.
  • diet, although dietary supplements such as fish oil may help.

How common is it and who gets it?

ADHD, as defined by DSM-5, is thought to affect around 5 per cent of children, with about 1.5 percent having severe ADHD as defined by ICD-10. Between 50 and 80 per cent of children with ADHD will still have it as teenagers, and up to 60 per cent of them will still have it as adults.

Boys are between 2 and 4 times as likely as girls to have ADHD. But in the UK between 6 and 9 times as many boys receive a diagnosis. This means that many girls with ADHD remain undiagnosed and untreated.

This may be because the condition is noticed more readily in boys – because they tend to show hyperactive and oppositional symptoms more than girls.

Getting help

The first port of call is your GP. In children below school age, unless the symptoms are extreme, it's very difficult to diagnose ADHD. However, once your child starts school, the teacher should be able to assess your child's behaviour and tell you if it's very different from the rest of the class.

Your GP will talk to you about your child's symptoms and medical history, and may refer you to a specialist in developmental disorders for further assessments.

At the same time, your school should ask the local education authority (LEA) to assess your child for special educational needs - which may involve discussions with educational psychologists, language specialists and occupational therapists.

How is it treated?

ADHD is treated by:

  • behavioural therapy
  • support at school
  • medication.

Other people also read:


Cognitive behavioural therapy: how can it help ADHD?


Based on a text by Dr Dan Rutherford, GP

Last updated