ADHD

Original Author: Dr Dorothy Simmonds and Dr Louise Ingram
Last Updated: 11th August 2018
Revisions: 8

Introduction

Attention Deficit Hyperactivity Disorder (ADHD) is a neurobehavioural disorder that is characterised by hyperactivity, inattention and impulsivity. It is not the child merely being “naughty” but an inability to focus, stay still or concentrate that they cannot help and that impacts their daily life, particularly their education.

Epidemiology

The prevalence of ADHD worldwide is around 7%1 and, while estimates vary, it is thought that approximately 1 in 20 UK children are affected.  ADHD is more common in boys than girls2 by a factor of between 2 and 4 times.  It might be that girls are underdiagnosed as they tend to have less disruptive forms of ADHD and may be less noticeable.

Up to 50% of children with ADHD have a co-morbid condition, such as Autistic Spectrum Disorder (ASD), learning difficulties (including dyslexia), communication disorders, oppositional defiance disorder, depression, anxiety, tics or Tourette Syndrome.

Pathophysiology

The pathophysiology of ADHD is not well understood.  Evidence has been found of structural and functional changes in the brains of children with ADHD, as well as changes in the levels of certain neurotransmitters, such as dopamine3.

It also has a genetic component, often running through families; twin studies have shown the heritability to be 88%4. There is also some evidence of interplay between genetic and environmental factors5.

Clinical Features / Diagnosis

NICE have issued guidance for the diagnosis of ADHD in children in the UK[i].  This guidance is based on the criteria from either the ICD-106 or DSM-V7.

ICD-10 criteria (where ADHD is referred to as “Hyperkinetic Disorder” or HKD) specify that symptoms must be of “early onset” (i.e. before 6 years old) and present for some time before diagnosis. They must be present in two or more settings and must be out of context for the child’s age and IQ.

The two main features for diagnosis are impaired attention and over-activity. Disinhibition, recklessness and lack of adherence to social norms (e.g. interrupting people) may be present but not necessary for a diagnosis with these criteria.  (The ICD-10 criteria exclude the diagnosis of ADHD in the presence of another pervasive developmental disorder or when the age of onset is uncertain but NICE do not support this exclusion.)

DSM-V criteria include three subtypes of ADHD – combined, predominantly inattentive type and predominantly hyperactive/impulsive presentation.

  • Inattention criteria include – “easily distracted by extraneous stimuli”, “forgetful in daily activities” and “often has difficulty sustaining attention in tasks or play activities”.
  • Hyperactivity criteria include – “often fidgets with hands or feet or squirms in seat”, “often talks excessively” and “is often on the go or often acts as if driven by a motor”.
  • Impulsivity criteria include – “often has difficulty waiting turn” and “often bursts out answers before questions have been completed”.

Diagnosis is made when at least six of the criteria from either inattention category or hyperactivity/impulsivity category are met and have been present from before the age of 12 for at least six months. The impairment must be present in more than one setting and there must be evidence of the symptoms impairing the child’s functioning. The symptoms must not be better explained by another diagnosis and be inconsistent with the child’s developmental level.

Children in whom inattention symptoms predominate may take longer to be noticed as having a problem, partly because they are not disruptive to other children.  The condition can still have a significant impact on their learning and attainment.

Examination

A general physical examination should be performed, in particular a cardiovascular examination including heart rate and blood pressure (in preparation for starting medication).

Height and weight should be measured and plotted on a growth chart.

Differential Diagnosis / Co-morbid conditions

If significant learning difficulties are present, then these should be considered before making a diagnosis (i.e. are the symptoms in keeping with the child’s developmental age).

Auditory processing disorder can present as children having trouble concentrating and following instructions, particularly in the presence of background noise – this is a disorder in which the brain has difficulty interpreting sounds and the information heard. It may also co-exist with ADHD and other conditions such as dyslexia.

Oppositional-Defiant Disorder or Conduct Disorders may present with features similar to ADHD, however they have separate diagnostic criteria. In Conduct Disorder, there are marked features of aggression; this is not usually a feature of ADHD. In Oppositional-Defiant Disorder there are features of anger, vindictiveness and being argumentative. Children with ADHD tend to not want to get in trouble but can’t help themselves, often getting carried away.

Other psychiatric conditions such as depression and anxiety should be considered before diagnosing ADHD. ADHD is often comorbid with Autistic Spectrum diagnostic criteria.

Investigations

There are several questionnaires that can be used to gather information, such as the Conner’s questionnaire8. A school observation is useful to observe the child’s functioning and interaction in the classroom, as well as a school report to find out the child’s academic attainment.  Information should be obtained from school, home or any other regularly visited environment (e.g. childminder, other relatives) in order to demonstrate that problems are present in more than one setting.

If considering medication, a family history must be taken as well as an ECG if there is any positive family history of serious cardiac disease or sudden death (this is because the medication used in ADHD can cause arrhythmias).

Management

NICE guidelines differentiate management into three groups; preschool children, mild-moderate ADHD and severe ADHD.

  • Preschool children: Medication is not recommended. Parents should be offered a parent training/education programme and nursery/pre-school teachers should be informed of the child’s diagnosis, severity of impairment, care plan and special educational needs.
  • Mild-moderate ADHD in school-age children with moderate impairment: the first line treatment is behavioural strategies9, usually delivered in the form of parent education sessions. Cognitive Behavioural Therapy and social skills training for the child can also be used. Teachers should also have received training on behavioural strategies for the classroom. These strategies can be effective, but only when the family are willing to engage. If behavioural strategies have not worked or not been taken up by the family, it may be appropriate to try medication.
  • Severe ADHD in school-age children with severe impairment: Medication is offered as the first line treatment. If medication is declined by child or family, they should be advised of the benefits of medication and if still unwilling, offered a group parent training/education programme.

There are five medications licenced for ADHD:

  • Methyphenidate; Stimulant medication. Available as immediate release preparations (e.g. Medikinet) and preparations that contain both immediate release and long release in different proportions (e.g. Medikinet XL, Concerta). Usually started at a smaller dose and titrated to response.
  • Atomoxetine; (Strattera) May be used when methylphenidate is not effective, if there is an associated tic disorder or anxiety disorder, or if there is a risk of stimulant medication being abused or redirected. Side effects include potential for liver damage.
  • Lisdexamfetamine; (Elvanse) Newer stimulant medication. Used when methylphenidate is not effective at maximum doses.[ii]
  • Guanfacine; (Intuniv) Non-stimulant medication. Used when stimulant medication is not suitable, not tolerated or ineffective.[iii]
  • Antipsychotics; should not be used in children with ADHD

The aim of using medication in children with ADHD is to improve their attention and concentration to allow them to achieve their educational potential; the timing of medication is chosen to maximise its effect at school.

All medications used in ADHD have side-effects, which can cause significant health problems or distress to the child.

Side effects include

  • raised blood pressure
  • palpitations (representing potentially dangerous arrhythmias)
  • disturbed sleep
  • impaired growth and appetite suppression (which is common and can be severe enough to stop the child eating and gaining weight)
  • there can also be problems with aggression or the child becoming more emotional, anxious or depressed

Prognosis

For many children with ADHD symptoms improve over time as they learn strategies to deal with the problems they have. Around 2/3rds will show no evidence of emotional or behavioural problems in adulthood10.

However, ADHD is associated with many adverse outcomes compared with peers without ADHD, such as increased substance abuse11, more criminal convictions12 and lower educational attainment13 and unemployment14.

References

  1. Thomas et al (2015) Prevalence of attention-deficit/hyperactivity disorder: a systematic review and meta-analysis. Pediatrics. Apr;135(4):e994-1001.
  2. Novik TS et al (2006) Influence of gender on attention-deficit/hyperactivity disorder in Europe–ADORE. Eur Child Adolesc Psychiatry. Dec;15 Suppl 1:I15-24.
  3. Purper-Ouakil D, Ramoz N, Lepagnol-Bestel AM, et al. (2011) Neurobiology of attention deficit/hyperactivity disorder. Pediatr Res; 69: 69R-76R.
  4. Larsson H, Chang Z, D’Onofrio BM, et al. (2014) The heritability of clinically diagnosed attention deficit hyperactivity disorder across the lifespan. Psychol Med; 44: 2223-2229.
  5. Nikolas M, Friderici K, Waldman I, et al.(2010) Gene x environment interactions for ADHD: synergistic effect of 5HTTLPR genotype and youth appraisals of inter-parental conflict. Behav Brain Funct; 6: 23.
  6. World Health Organization. (1993) The ICD-10 Classification of Mental and Behavioural Disorders. Available at: www.who.int/entity/classifications/icd/en/bluebook.pdf.; 1: 1-263. Accessed 12/7/2017.
  7. American Psychiatric Association. (2013) Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.
  8. http://www.pearsonclinical.co.uk/Psychology/ChildMentalHealth/ChildADDADHDBehaviour/Conners3rdEdition(Conners3)/Conners3rdEdition(Conners3).aspx. Accessed on 12th July 2017
  9. NICE guideline Attention deficit hyperactivity disorder: diagnosis and management. Clinical guideline [CG72] Published date: September 2008 Last updated: February 2016
  10. Manuzza and Klein (2000) Long-term prognosis in attention-deficit/hyperactivity disorder.Child Adolesc Psychiatr Clin N Am. Jul;9(3):711-26.
  11. Biederman J et al (2006) Young adult outcome of attention deficit hyperactivity disorder: a controlled 10-year follow-up study. Psychol Med. Feb;36(2):167-79.
  12. Fletcher J and Wolfe B. (2009) Long-term Consequences of Childhood ADHD on Criminal Activities J Ment Health Policy Econ. Sep; 12(3): 119–138.
  13. Loe IM, Feldman HM.(2007) Academic and educational outcomes of children with ADHD. Ambul Pediatr. 2007 Jan-Feb;7(1 Suppl):82-90.
  14. Biederman J and Faraone S.(2006) The Effects of Attention-Deficit/Hyperactivity Disorder on Employment and Household Income MedGenMed; 8(3): 12.

[i] NICE guideline for diagnosis and management of ADHD accessed on 19/09/2017 at https://www.nice.org.uk/guidance/CG72

[ii] Methylphenidate, atomoxetine and dexamfetamine for attention deficit hyperactivity disorder (ADHD) in children and adolescents.  NICE technology appraisal guideline.  Accessed at https://www.nice.org.uk/guidance/TA98 on 08/11/17

[iii] Attention deficit hyperactivity disorder in children and young people: guanfacine prolonged-release.  NICE Evidence Summary https://www.nice.org.uk/advice/esnm70/chapter/Key-points-from-the-evidence Accessed 08/11/17

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