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Attention-Deficit / Hyperactivity Disorder

Attention-Deficit / Hyperactivity Disorder

What is attention-deficit / hyperactivity disorder?

Attention-deficit / hyperactivity disorder (ADHD) is a common neurobehavioural developmental disorder. Children suffering from ADHD usually present with hyperactivity, impulsiveness and inattention symptoms. These symptoms create obstacles in learning and interpersonal relationships, which may lead to emotional problems, low self-esteem, and difficulties in coping with everyday life.


How common is attention-deficit / hyperactivity disorder?

How common is attention-deficit / hyperactivity disorder?

Prevalence rate

The prevalence of ADHD among Hong Kong school children is similar to that of the international figure, which is around 5-9%.

Gender ratio

It usually affects male more than female.


What causes attention-deficit / hyperactivity disorder?
A smaller-than-normal brain volume

Up till now, the definite causes of ADHD remain unclear. But research points out that the volume of the brain of an ADHD child may be smaller than that of a normal child by 3-5%. This reduction in size is particularly significant for the frontal lobe and temporal lobe. The frontal lobe is the brain area which is responsible for attention, impulse control, and some higher cognitive functions, such as planning, organising and problem-solving.

Imbalanced neurotransmitter

Research also points out that there may be an imbalance in the dopamine system (a type of neurotransmitter) in the patient’s brain.


What are the symptoms of attention-deficit / hyperactivity disorder?

What are the symptoms of attention-deficit / hyperactivity disorder?

Symptoms of ADHD include:

  • Fidgety on seat, unable to sit still
  • Frequently off-seat
  • Run and climb excessively when it is socially inappropriate
  • Always 'on the go'
  • Talkative and cannot keep in silence
  • Continuously chatter or interrupt people
  • Blurt out an answer before questions have been finished
  • Have difficulty in taking turns or queuing up
  • Low frustration tolerance
  • Cannot concentrate, take a long time to or even fail to complete tasks
  • Cannot thoroughly follow instructions
  • Appear daydreaming when being talked to
  • Avoid mental task
  • Miss small details, frequently make careless mistake
  • Forgetful, frequently lose belongings
  • Disorganised

Tips for parents:

Many children are inattentive and restless, especially during their very young ages. This does not necessarily mean they have ADHD. To establish the diagnosis of ADHD, the child must be assessed by a professional. Please consult your doctor if you suspect your child is suffering from ADHD.

Besides, clinical features of ADHD evolve with the children’s developments:

Infancy and preschool age
  • The core feature is hyperactivity. They are energetic and are often running about or climbing.
  • Some children may cry and lose their temper easily. They may have greater emotional response to events and become excited or angry easily.
  • Some may have sleeping problems as well.
  • Problems related to inattention will become increasingly obvious.
  • Children may have difficulties in learning. Their inattention in class may affect their classroom and academic performance.
  • They are impulsive, weak at self-control and compliance, leading to discipline punishments, problems in social relationships and conflict with peers.
  • Some children may also show oppositional, risk-taking and/or dangerous behaviours.


What are the treatments of attention-deficit / hyperactivity disorder?

Medication and behavioural treatment can bring significant improvement over symptoms of ADHD.

Type Central Nervous System (CNS) stimulant medication Non-CNS stimulant medication
Common drugs
  • Methylphenidate
    • Ritalin: Short-acting, duration is around 3-4 hours (usually needs 2-3 doses per day)
    • Concerta: Long-acting, duration is around 12 hours (usually needs a single daily dose)
  • Imipramine
  • Clonidine
  • Atomoxetine
Indications Around 65-80% of ADHD children show a significant response to stimulant medication, e.g. reduced activity level, reduced disruptive and impulsive behaviours and increased attention span Usually used as second line agents and in children who do not show response to the CNS stimulant medication
Mechanism of action Helps to correct the dopaminergic and noradrenergic imbalance in the brain and hence improve the inattention, hyperactive and impulsive symptoms.
Side effects/ points to note
  • Loss of appetite, gastrointestinal upset, headache, insomnia
  • May lower the seizure threshold in patients suffering from epilepsy
  • Contraindicated in patients suffering from glaucoma or psychosis
  • Side effects are mild and transient, and they usually improve upon reduction of dosage and rearrangement of dosing schedule
  • Imipramine:
    • Dry mouth, constipation, hand tremor, palpitation
    • Overdose may cause fatal cardiac arrhythmia
  • Clonidine:
    • Dizziness, palpitation, low blood pressure, dry mouth
  • Atomoxetine:
    • Side effects are similar to CNS stimulant medication but at a lesser degree

If patients experience any undesirable side effects during drug treatment, please consult the doctor as soon as possible to clarify the worries and make appropriate adjustments.

Tips for parents: How to deal with the side effects of medication?

  • Loss of appetite: Appetite resumes when the medication effect wanes off. Weight loss as a consequence of loss of appetite can be counteracted by the consumption of high energy food.
  • Gastrointestinal upset: Taking medication after a meal can relieve the gastrointestinal upset.
  • Insomnia: Avoid taking medication at night. Earlier dosing schedule may relieve the problem.
  • Drug Holiday: Some parents may choose to withhold medication during school holiday (Drug holiday). This may help reduce the influence of side effects, but it may also worsen the symptoms. Careful consideration and discussion with the doctor is necessary.
Behavioural Treatment

Behavioural therapy is based on learning theories and can help to correct children’s inappropriate behaviours and build up new and appropriate behaviours. Parents can join effective parenting training to learn some systemic ways of disciplines, such as setting up objective goals, giving clear instructions, and appropriate rewards and punishments, to modify their children’s behaviours. Besides, children can receive such training to improve their emotional and behavioural problems too.

  • Effectively improve the behavioural and emotional problems
  • Effectively improve the learning and social difficulties
Treatment Procedures
  • Observation and recording: Defining the behavioural problem by observation and recording of the behaviour, including the time, place and frequency of occurrence, parental reaction, etc.
  • Analysis: Analysing the antecedents and consequences of the behaviour
  • Reinforcement/punishment: Changing these antecedents and consequences by facilitative environment and proper use of reinforcement/punishment etc., to increase appropriate behaviours and decrease inappropriate behaviours
  • Regular reviews: Since a child has different needs at different stages, review of the child’s condition and change of strategies may be needed

Tips for parents:

  • Good parent-child relationships are keys to success.
  • Teaching the child on proper ways to handle emotions, effective problem-solving skills, and the establishment of good living habits are also beneficial and important.


How to support and help children with attention-deficit / hyperactivity disorder?
How to support and help children with attention-deficit / hyperactivity disorder?
Supports for ADHD suspected cases:

Parents may approach the following organisations for initial evaluation and further referral when necessary:

  • Department of Health’s Maternal and Child Health Service (preschool) or Student Health Service (school-age)
  • Your family doctors, clinical or educational psychologist
Supports for children with ADHD:

Parents may seek help from the following organisations:

  • The Child Assessment Service of the Department of Health offers behavioural and developmental assessment for the child, as well as interim support for the family, including parent workshops and parenting skill training groups.
  • Under the Hospital Authority, Child and Adolescent Mental Health Services and Department of Paediatrics and Adolescent Medicine provide assessment, as well as medical and behavioural treatment for children with ADHD.
  • Psychiatrists and paediatricians in private practice may prescribe medication for children with ADHD.
  • In schools, supports are provided to teachers and children by school social workers and educational psychologists.
Supports for carers:
  • Many community centres and non-government organisations also offer training programmes and activities for children with ADHD and their families.
  • Apart from seeking professional help, parents, teachers and other carers should be caring and considerate to help children with ADHD to tackle the problems.


Can children with attention-deficit / hyperactivity disorder grow up normally?

Research has demonstrated that some children’s ADHD symptoms persist to their adolescence and adulthood, by about 80% and 65% respectively.

Possible clinical features:

Late childhood and early adolescence
  • Although the severity of hyperactivity may decline, features of inattention and impulsivity often remain
  • New areas of potential problems may emerge, including frequent engagement in interpersonal conflict, fighting or substance use
  • Inattention and impulsivity are the core symptoms
  • Difficulty concentrating at work
  • Distractibility, disorganisation, inefficiency, impatience and impulsivity may persist

ADHD children may be confronted with various challenges when they are growing into their adolescence and adulthood. Appropriate treatments, supports, and cooperation among parents, carers, and medical and educational professionals, can strengthen their protections, control ADHD symptoms and reduce the risks for them to suffer from other problems.

Besides, most ADHD children will have settled down by the time they reach their mid-teens. They will have been able to catch up with their learning, improve their school performance and develop satisfactory interpersonal relationships.



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Reference source(s): Websites of the Institute of Mental Health, Castle Peak Hospital and the Child Assessment Service, Department of Health