Attention deficit hyperactivity disorder

Synonyms: hyperkinetic disorder, attention deficit disorder (ADD)

What is attention deficit hyperactivity disorder?

Attention deficit hyperactivity disorder (ADHD) is a persistent pattern of inattention and/or hyperactivity-impulsivity that is more frequent and severe than is typically observed in individuals at a comparable level of development and which interferes with functioning and/or development. 2018 Guidelines from the National Institute for Health and Care Excellence (NICE) state that for a diagnosis of ADHD, symptoms of hyperactivity/impulsivity and/or inattention should:¹

• Meet the diagnostic criteria in the Eleventh Revision of the International Classification of Diseases and Related Health Problems (ICD-11).²

• Be associated with at least moderate psychological, social and/or educational or occupational impairment based on interview and/or direct observation in multiple settings

• Be pervasive, occurring in two or more important settings, including social, familial, educational and/or occupational settings.

The ICD-11 diagnostic criteria for ADHD²

The World Health Organization (WHO) International Classification of Diseases (ICD-11) provides the following definition:

• Attention deficit hyperactivity disorder is characterised by a persistent pattern (at least 6 months) of inattention and/or hyperactivity-impulsivity that has a direct negative impact on academic, occupational, or social functioning.

• There is evidence of significant inattention and/or hyperactivity-impulsivity symptoms prior to age 12, typically by early to mid-childhood, though some individuals may first come to clinical attention later.

• The degree of inattention and hyperactivity-impulsivity is outside the limits of normal variation expected for age and level of intellectual functioning.

  • Inattention refers to significant difficulty in sustaining attention to tasks that do not provide a high level of stimulation or frequent rewards, distractibility and problems with organisation.

  • Hyperactivity refers to excessive motor activity and difficulties with remaining still, most evident in structured situations that require behavioural self-control.

  • Impulsivity is a tendency to act in response to immediate stimuli, without deliberation or consideration of the risks and consequences.

• The relative balance and the specific manifestations of inattentive and hyperactive-impulsive characteristics varies across individuals and may change over the course of development.

• In order for a diagnosis to be made, manifestations of inattention and/or hyperactivity-impulsivity must be evident across multiple situations or settings (eg, home, school, work, with friends or relatives), but are likely to vary according to the structure and demands of the setting.

• Symptoms are not better accounted for by another mental, behavioural, or neurodevelopmental disorder and are not due to the effect of a substance or medication.

How common is ADHD? (Epidemiology)³

• Globally, ADHD is estimated to affect 5% of children. In the UK, the prevalence of ADHD in adults is estimated at 3% to 4%.

• ADHD is most often diagnosed in children aged 3-7 years, but it may not be recognised until later in childhood and sometimes not until adulthood.

• ADHD is more commonly diagnosed in boys than in girls. The ratio estimates vary but in the UK is thought to be 2–5:1. However, this difference may be due to boys presenting more often with disruptive behaviour that prompts referral, whereas girls more often have the inattentive subtype and have lower comorbidity with oppositional defiant disorder and conduct disorder.

• Of the three subtypes of ADHD:

  • Inattentive subtype accounts for 20-30% of cases.

  • Hyperactive-impulsive subtype accounts for about 15% of cases.

  • Combined subtype accounts for 50-75% of cases..

Causes of ADHD (aetiology)¹³

The cause is unknown but there appears to be a combination of genetic and environmental factors involved. Twin studies demonstrate a high inheritability.⁴Those with a first-degree relative with ADHD are more likely to have the condition. Environmental and other risk factors include:

• Low birth weight and preterm delivery.

• Maternal smoking or alcohol exposure during pregnancy.

• Epilepsy.

• Acquired brain injury.

• Lead exposure.

• Iron deficiency.

• Being in the care of others who are not parents ('looked after').

• Maternal mental health problems.

• Maternal substance misuse.

• The presence of other neurodevelopmental or mental health disorders such as oppositional defiant disorder or conduct disorder, mood disorders (eg, anxiety and depression), autism spectrum disorder, tic disorders, learning disability and specific learning difficulties.

ADHD assessment¹

• ADHD should be considered in all age groups. Diagnosis should only be made by a specialist psychiatrist, paediatrician or other healthcare professional with training and expertise in the diagnosis of ADHD. Diagnosis should be based on:
  

  • A full clinical and psychosocial assessment. Discuss behaviour and symptoms in the different domains and settings of the person's everyday life.

  • A full developmental and psychiatric history, and observer reports and an assessment of mental state.

  • Rating scales such as Strengths and Difficulties questionnaires or the Conners' rating scale may be used by those with expertise, and may also be useful for monitoring, but should not be used alone to make a diagnosis.

• An assessment should include an assessment of the person's needs, co-existing conditions, social, familial and educational or occupational circumstances and physical health. For children and young people there should also be an assessment of their parents' or carers' mental health.

• Determine the severity of behavioural and/or attention problems suggestive of ADHD and how they affect the child or person and their parents/carers where relevant. Assess impact on their life. For example:

  • For children: ability to make/keep friends, school achievement, family relationships; ability to eat/self-care/travel independently; ability to avoid common hazards (crossing road safely, etc); emotional state.

  • For adolescents and adults: ability to avoid criminal activity and substance misuse and dangerous driving; ability to make and keep relationships, school or occupational function and achievement; ability to organise daily activities.

Differential diagnosis⁵

• A number of conditions can have symptoms similar to ADHD, including:

  • Thyroid disease.

  • Anxiety.

  • Depression.

  • Bipolar disorder.

  • Autistic spectrum disorder.

  • Personality disorders.

  • Oppositional defiant disorder and conduct disorder.

  • Tic disorders.

  • Fetal alcohol syndrome.

  • Substance use disorders.

• Steroids, antihistamines, anticonvulsants, beta-agonists, caffeine, and nicotine can also have adverse effects that mimic ADHD symptoms.

• The NICE guideline notes that girls and women are more likely to be mis-diagnosed with another mental health condition or neurodevelopmental disorder.¹

Management of ADHD¹³

Referral

• In children and young people, if the problems are having an adverse impact on development or family life, consider:
  

  • Watchful waiting for up to ten weeks. (If the problems are associated with severe impairment, refer directly to secondary care.)

  • Offering referral to a group-based ADHD-focused support; this should not wait for a formal diagnosis of ADHD.

  • If the problems persist with at least moderate impairment, specialist referral is needed to confirm the diagnosis and to start management. Referral may be to a specialist paediatrician, a child psychiatrist, Child and Adolescent Mental Health Services (CAMHS).

• Adults presenting with symptoms of ADHD who do not have a childhood diagnosis of ADHD, should be referred for assessment by a mental health specialist trained in the diagnosis and treatment of ADHD, where there is evidence of typical manifestations of ADHD (hyperactivity/impulsivity and/or inattention) that:

  • Began during childhood and have persisted throughout life.

  • Are not explained by other psychiatric diagnoses (although there may be other co-existing psychiatric conditions); and

  • Have resulted in or are associated with moderate or severe psychological, social and/or educational or occupational impairment.

• Adults who have previously been treated for ADHD as children or young people and present with problematic symptoms suggestive of continuing ADHD should be referred to general adult psychiatric services for assessment.

• Do not diagnose or start medication for ADHD in children and young people in primary care.

General principles of management

• Parents and affected children need a great deal of explanation and support. There is a great deal of unproven advice available for parents and it is very important that time be taken to explain properly and to discuss the diagnosis and appropriate treatments.

• Give people with ADHD and their families written information about self-help, support groups, and voluntary organisations, as appropriate. These include:

  • The National Attention Deficit Disorder Information and Support Service (ADDISS).

  • Adult Attention Deficit Disorder UK (AADDUK).

  • Mind.

• A structured discussion from a specialist professional is important for many reasons including:

  • Stressing the positive aspects of the diagnosis (accessing help, understanding the issues and symptoms) as well as acknowledging the negative aspects such as stigma.

  • Discussing potential effects of ADHD.

  • Discussing education or employment issues.

  • Discussing effects on relationships.

  • Explaining the potential effect on driving.

  • Offering advice on appropriate sources of information.

  • Offering advice about consistent behaviour management and parenting skills and explaining that any recommendation of parent-training/education does not imply bad parenting, but that extra parenting skills are needed for children and young people with ADHD.

  • Asking about goals, preferences for treatment, concerns and worries.

  • Forming an individualised shared treatment plan.

• With consent, liaison with school/college/university is helpful. Modifications can be made to the learning environment to optimise it for the individual with ADHD.

• Stress the value of a balanced diet, good nutrition and regular exercise for children and young people with ADHD.

• Eliminating artificial colouring and additives from the diet is not recommended as a generally applicable treatment for ADHD.

• Dietary fatty acid supplements are not recommended for the treatment of ADHD.

• Advise parents or carers to keep a diary if there are foods or drinks that appear to affect behaviour. If the diary supports a link between any foods or drinks and behaviour, offer referral to a dietician. Further management (such as elimination of specific foods) should be jointly undertaken by the dietician, mental health specialist or paediatrician, and the family.

Pharmacological management⁶

• All medication for ADHD should only be initiated by a healthcare professional with training and expertise in diagnosing and managing ADHD. It should always form part of a comprehensive treatment plan that includes psychological, behavioural and educational advice and interventions.

• Medication is usually not recommended for pre-school children with ADHD, for whom an ADHD-focused group parent-training programme is normally recommended first-line.

• For school-aged children and young people with ADHD, treatment with medication should be reserved for those with ADHD symptoms causing persisting significant impairment in at least one domain despite implementation of other management options such as environmental modifications, ADHD-focused support and education, parenting strategies, and liaison with school or college, where consent is given.

• For adults with symptoms causing significant impact, medication is usually recommended first-line.

• Where pharmacological treatment is considered appropriate, methylphenidate is generally offered first-line, with lisdexamfetamine, dexamfetamine, and atomoxetine, as alternatives if methylphenidate is contra-indicated, not tolerated, or ineffective.

• Baseline physical assessment before starting medication should include:

  • Pulse.

  • Blood pressure.

  • Weight and height (plotted on centile charts).

  • Cardiovascular assessment (and referral to cardiology if any personal or family history of relevant cardiac conditions).

  • An ECG should also be considered but is not needed before starting stimulants, atomoxetine or guanfacine if cardiovascular history and examination are normal and the person is not on medicine that poses an increased cardiovascular risk.

• NICE guidance advises the following pathway for medication for children over the age of 5 years, and young people:

  • Methylphenidate (either short- or long-acting) first-line.

  • Consider changing to lisdexamfetamine if a six‑week trial of methylphenidate at an adequate dose has not resulted in sufficient benefit.

  • Consider dexamfetamine if ADHD symptoms are responding to lisdexamfetamine but it is not tolerated.

  • Consider atomoxetine or guanfacine if no response or intolerance of methylphenidate and lisdexamfetamine.

• NICE guidance advises the following pathway for pharmacological treatment for adults with ADHD:

  • Lisdexamfetamine or methylphenidate may be used as first-line pharmacological treatment.

  • If either is not sufficiently effective after six weeks, consider switching to the other.

  • Consider dexamfetamine where ADHD symptoms are responding to lisdexamfetamine but it is not tolerated.

  • Consider atomoxetine if there is intolerance to lisdexamfetamine or methylphenidate or if symptoms have not responded to separate six-week trials of each.

  • An ECG is not needed before starting stimulants, atomoxetine or guanfacine, unless the person has any of the risk features for heart disease, when a referral to cardiology is required (see 1.7.5 of the NICE guidance for details), or a co-existing condition that is being treated with a medicine that may pose an increased cardiac risk.

• If the above options haven't been successful, a second opinion or tertiary referral is advised. Tertiary services may consider other options or unlicensed treatments such as clonidine or atypical antipsychotics.

• Treatment should be reviewed by a specialist at least once a year and trials of treatment-free periods, or dose reductions considered where appropriate.

Follow-up and monitoring of people on medication

After titration and dose stabilisation, prescribing and monitoring of ADHD medication should be carried out under Shared Care Protocol arrangements with primary care. There should be regular review of efficacy and adverse effects of medication.

Adverse effects to ask about include tics, sexual dysfunction (atomoxetine), fainting due to orthostatic hypotension (guanfacine), seizures, sleep, and worsening behaviour. Also consider stimulant misuse and diversion.

Physical checks include:

• Height every six months in children and young people.

• Weight:

  • Every three months in children aged 10 years and under.

  • At three and six months in children over 10 years of age, then at six-monthly intervals.

  • Every six months in adults.

• Plot height and weight on centile charts in children and young people. This should be reviewed by the specialist health professional responsible for treatment.

• Heart rate and blood pressure every six months, and before and after any dose changes.

• What to look out for (seek advice from specialist if any of the following occurs):

  • Sustained resting tachycardia (>120 bpm).

  • Arrhythmia.

  • Systolic blood pressure greater than the 95th percentile (or a clinically significant increase) measured on two occasions.

  • If a child or young person is not reaching the height expected for their age and centile (a planned break in treatment over school holidays may be required to allow 'catch-up' growth).

  • If other significant adverse effects develop.

Adults prescribed an amphetamine (for example, dexamfetamine or lisdexamfetamine) should be advised they should not drive if they feel drowsy, dizzy, unable to concentrate or make decisions, or have blurred or double vision.

Adults should also be warned about the legal implications of driving with amphetamines - police may require roadside or blood tests for drug levels. As long as driving is not impaired, and there is evidence they are taking the medication on the advice of a health professional, they will avoid prosecution.

A specialist should review medication at least once a year and discuss with the person taking it (and their parents/carers where appropriate) whether medication should be continued.

Psychosocial treatments

For pre-school children, an ADHD-focused group parent-training programme is normally recommended first-line. For school-aged children, group-based support is offered to parents/carers and/or the child or young person with ADHD. It includes education and information on the causes and impact of ADHD and advice on parenting strategies. With consent, liaison with school, college or university should occur.

Individual parent-training programmes for parents and carers of children and young people with ADHD are offered when there are particular difficulties for families in attending group sessions (disability, language differences, learning disability, parental ill health, problems with transport, other factors suggesting poor prospects for therapeutic engagement, complex family needs).

Teachers who have received training about ADHD and its management should provide behavioural interventions in the classroom to help children and young people with ADHD.

Cognitive behavioural therapy (CBT) is an option for young people with ADHD who have benefited from medication but whose symptoms are still causing a significant impairment in at least one domain. CBT may be helpful in addressing the following areas:

• Social skills with peers.

• Problem-solving.

• Self-control.

• Active listening skills.

• Dealing with and expressing feelings.

Non-pharmacological treatment may be used in adults who choose not to take medication, or in whom it has not been effective or not tolerated. A structured supportive psychological intervention focused on ADHD may be used, with regular follow‑up either in person or by phone. Treatment may involve CBT.

Prognosis³

A 2006 meta-analysis of follow-up studies of children with ADHD found that by the age of 25:⁷

• About 15% continued to have ADHD.

• 65% had persistence of some symptoms and continuing functional impairment, with psychological, social or educational difficulties.

ADHD is associated with poverty, lower family income and social class. In adults, it is more frequent in the unemployed and in people with disabilities.

Over time, inattentive symptoms tend to persist and hyperactive-impulsive symptoms tend to recede.

Comorbidity may significantly affect prognosis. ADHD is associated with increased prevalence of psychiatric disorders, including oppositional defiant disorder (ODD), conduct disorder, substance abuse, and possibly mood disorders, such as depression and mania.

Other conditions such as autism spectrum disorder, dyslexia, dyscalculia, and dyspraxia are also more common in those with ADHD. The person's overall prognosis may therefore depend on the severity and management of any co-existing disorders.

Young people and adults with ADHD may have associated problems - eg, self-harm, a predisposition to road traffic (and other) accidents, substance misuse, delinquency, anxiety states and academic underachievement.