Attention Deficit Hyperactivity Disorder (ADHD)

Introduction

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental condition characterised by an abnormally high activity level and an inability to concentrate.

ADHD affects a person’s development and ability to carry out everyday tasks. It primarily affects children but can be diagnosed at any age. Importantly, features must be present before the age of seven and be consistent across at least two settings.

ADHD is estimated to have a global prevalence of 5% (3-4% in the UK) and a male to female ratio of 3:1. However, it is thought to be under-recognised and diagnosed in girls.

Aetiology

The cause of ADHD is currently unknown. However, many studies have demonstrated a link between ADHD and a combination of environmental and genetic factors.^1,2,3

Risk factors

Risk factors for ADHD include:^1,4,5

• Prematurity
• Low birth weight
• Low paternal education
• Prenatal smoking
• Maternal depression

Clinical features

All the features of ADHD are part of the normal range of childhood behaviours.

A diagnosis of ADHD should be considered when a child has many of these features and they are adversely affecting the child’s life.⁶

Typical features of ADHD include:

• Short attention span
• Quickly losing interest in tasks
• Constantly fidgeting or unable to sit still
• Impulsive behaviour
• Described as disruptive
• Poor organisational skills
• Acting without thinking

Differential diagnoses

There are several important differential diagnoses to consider when a child (or adult) presents with suspected ADHD.^3,7 

Anxiety and depression

Anxiety can often present with inattention due to excessive worry and rumination.⁷ Patients may report difficulty concentrating, forgetfulness and being easily distracted. Features more suggestive of anxiety include worry, palpitations and feeling like something awful might happen.

Depression can present with poor concentration.⁷ It is important to ask patients if they have been feeling down, low, or are no longer finding previously enjoyable activities pleasurable.

Autism

Children with autism spectrum conditions often have poor impulse control and may be described as disruptive due their rigidity of thought. Parents should be asked about the child’s development in communication, social skills, and imaginative play.

Childhood trauma 

Both childhood trauma and PTSD can cause children to perform less well in school, appear inattentive and disruptive. The history should sensitively enquire about any precipitating events to new behaviours. Children may display avoidance behaviours or develop anxiety symptoms as described above.

Other differential diagnoses

Less common differential diagnoses to consider include personality disorders, oppositional defiant disorder, conduct disorder, learning disabilities and epilepsy.⁷

Diagnosis

ADHD is a clinical diagnosis. A formal diagnostic assessment should be carried out by a specialist. In primary care, it is important to assess the impact that the symptoms are having on the patient.³

In school-aged children enquire about friendships, school, and personal safety. Issues for adolescents may arise at school or work, maintaining intimate relationships and performing household tasks such as shopping or chores.⁸  

Primary care physicians with the appropriate training may use the strengths and difficulties questionnaire or the Conners’ rating scale to aid their assessment.^3,6,8 In adults, assessment can be aided by the Diagnostic Interview for ADHD in Adults (DIVA) questionnaire.⁹

There are various rating scales available to clinicians. They are not diagnostic but help gain structured information to aid with the diagnosis.

Diagnosis of ADHD made using the DSM-5 diagnostic criteria (Table 1):^3,8

• Children up to the age of 16: there must be six or more symptoms of inattention and six or more symptoms of hyperactivity and impulsivity.
• For those aged 17 and over: only five or more symptoms are required from each category.

The symptoms must occur in multiple settings (e.g. at home and school), have been present for at least six months and are not better explained by another disorder.^3,8

For example, if a child only displays these behaviours at school but is calm at home it suggests that the cause may be environmental. If the behaviours only continue for two weeks, then they may be better explained by a situational cause.

Table 1. DSM-5 diagnostic criteria for ADHD.^3,8

Note that impulsivity in adults may be reflected in drug or alcohol use, forensic history and employment history.¹⁰

Management

Primary care management

Initial primary care management involves a period of watchful waiting for up to ten weeks including encouraged self-help and simple behavioural management.

Establishing a healthy diet and regular exercise can offer significant improvements with behaviour. Parents or carers should be offered a referral to a group-based ADHD focussed support program.⁸ This allows them to meet others with similar experiences, feel less alone and pick up useful strategies from peers. 

Simple behaviour management can include reward charts, positive redirection, 1-2-3-reward visuals and use of self-imposed concentration breaks. Positive redirection involves telling a child what they should be doing, rather than highlighting the undesired behaviour.

It is useful for avoiding trigger words such as “No!” and provides the child with clear direction of how they are expected to proceed.

1-2-3-reward visuals are used to break down tasks into three simple steps and help the child understand how they are progressing through a task. Completed stages should be ticked off by the child as they go. For example, “Get ready for bed.” can be broken down into:

• One: change into your pyjamas
• Two: brush your teeth
• Three: get into bed
• Reward: reading a story

Primary care physicians should refer children to child and adolescent mental health services (CAMHS) or a specialist paediatrician if their symptoms are severe or their issues persist after simple self-help measures.⁸

Secondary care management

First-line management for ADHD is an ADHD-focussed group parent training program. Medication may be offered if symptoms are still causing significant issues. The first-line medication is methylphenidate. Cognitive based therapy (CBT) may be offered as an adjunct to medication.⁸

Methylphenidate is, counterintuitively, a central nervous system stimulant. It can cause growth retardation, weight loss, tachycardia, and hypertension. As such, children taking this medication need to have their height, weight, heart rate and blood pressure measured every six months.¹¹

Complications

More recent studies show that symptoms of ADHD persist into adulthood for as many as 60% of affected individuals. Adverse effects of these continued symptoms can include:^3,6

• Lower educational and employment attainment
• Poor self-esteem
• Criminal behaviour
• Relationship issues
• Sleep disturbance
• Substance abuse
• Road traffic accidents
• Self-harm

Key points

• ADHD is a condition characterised by hyperactivity, inattention and impulsivity. It is mostly diagnosed in children but can affect patients of all ages.^1,3,6
• A formal diagnosis of ADHD is made by a specialist using the criteria set out in the DSM-5. Patients aged 16 and under require six or more features of both inattention and hyperactivity or impulsivity. Those 17 and over only require five of each.³
• Conservative management of ADHD includes simple behaviour management strategies and group parental ADHD training sessions.⁸
• Medical management is typically initiated by a specialist after conservative measures have failed. Methylphenidate is the first-line medication.⁸
• In patients taking methylphenidate, it is important to monitor patients for side effects by recording their height, weight, blood pressure and heart rate every six months.^8,11 

Reviewers

Dr Nadia Saleem

Consultant Psychiatrist in CAMHS, Medical Lead for Child and Adolescent Mental Health Service, Coventry and Warwickshire Partnership NHS Trust

Dr Rupinder Kaler

Consultant Psychiatrist, Coventry and Warwickshire Partnership NHS Trust

Editor

Dr Chris Jefferies

References

1. NICE CKS. Attention deficit hyperactivity disorder – Causes. 2021. Available from: [LINK]
2. Larsson H, Chang Z, D’Onofrio BM, et al. The heritability of clinically diagnosed attention deficit hyperactivity disorder across the lifespan. Psychol Med. 2014 Jul44(10):2223-9.
3. Patient info. Attention deficit hyperactivity disorder. 2020. Available from: [LINK]
4. Sciberras E, Mulraney M, Silva D, Coghill D. Prenatal risk factors and the etiology of ADHD – Review of Existing Evidence. 2017.
5. Sagiv SK, Epstein JN, Bellinger DC, Korrick SA. Pre- and postnatal risk factors for ADHD in a nonclinical pediatric population. J Atten Disord. 2013;17(1):47-57.
6. Harpin V. The effect of ADHD on the life of an individual, their family,
   and community from preschool to adult life. Arch Dis Child 2005;90(Suppl I):i2–i7.
7. NICE CKS. Attention deficit hyperactivity disorder – Differential diagnosis. 2021. Available from: [LINK]
8. NICE CKS Attention deficit hyperactivity disorder – Management. 2021. Available from: [LINK]
9. Royal college of psychiatrists. ADHD in adults, good practice guidelines. 2017. Available from: [LINK]
10. Roberts W, Peters JR, Adams ZW, Lynam DR, Milich R. Identifying the facets of impulsivity that explain the relation between ADHD symptoms and substance use in a nonclinical sample. Addict Behav. 2014;39(8):1272-1277.
11. BNF. Methylphenidate hydrochloride. 2021. Available from: [LINK]