ADHD in Children
Attention deficit hyperactivity disorder is a neurodevelopmental condition characterised by inattention, hyperactivity, and impulsivity, affecting approximately 5% of school-age children in the UK.
Key Facts
Prevalence is approximately 3-5% of school-age children in the UK; male:female ratio ~3-4:1 (likely under-diagnosed in girls) NICE NG87 is the key guideline — recommends watchful waiting with environmental modifications as first line in under-5s Diagnosis is clinical, based on DSM-5 criteria — symptoms in ≥2 settings (e.g., home and school), present before age 12, lasting ≥6 months Three presentations: Predominantly inattentive, predominantly hyperactive-impulsive, and combined type First-line pharmacotherapy in children ≥5 years: Methylphenidate (Ritalin, Concerta XL) — a CNS stimulant; starting dose 5mg BD-TDS (immediate-release) Lisdexamfetamine is second-line if methylphenidate is ineffective or not tolerated (NICE NG87) Non-pharmacological: Behavioural parent training programme is first-line for all ages; CBT and social skills training in older children Monitoring: Height, weight, heart rate, and blood pressure should be measured every 6 months on stimulant medication
Overview
Key Facts
ADHD is a common neurodevelopmental disorder that affects attention, impulse control, and activity levels. It has significant impact on academic achievement, social relationships, and family functioning. It is a clinical diagnosis requiring comprehensive assessment in multiple settings.
Epidemiology
Prevalence in UK children is approximately 3-5%, making it one of the most common neurodevelopmental conditions. Male:female ratio is approximately 3-4:1 in clinic samples, though community studies suggest a ratio closer to 2:1 (suggesting under-diagnosis in girls). Predominantly inattentive type is more common in girls. Approximately 65% of children with ADHD continue to have impairing symptoms in adulthood.
Aetiology
ADHD is a highly heritable condition (heritability ~76%):
- Genetic: Polygenic; associated with dopamine transporter (DAT1) and dopamine receptor (DRD4, DRD5) gene variants
- Environmental: Prematurity, low birth weight, prenatal tobacco/alcohol exposure, lead exposure, severe early deprivation
- Neuroanatomical: Reduced volume of prefrontal cortex, basal ganglia, and cerebellum; delayed cortical maturation
Pathophysiology
ADHD involves dysregulation of catecholamine neurotransmission, particularly dopamine and noradrenaline, in the prefrontal cortex and fronto-striatal circuits. This results in impaired executive function (working memory, inhibition, attention regulation, planning). The prefrontal cortex is hypoactive, explaining why stimulant medications (which increase dopaminergic/noradrenergic transmission) paradoxically improve attention and reduce hyperactivity.
Clinical Presentation
Inattention Symptoms
- Difficulty sustaining attention in tasks or play
- Does not seem to listen when spoken to directly
- Fails to follow through on instructions, schoolwork
- Difficulty organising tasks and activities
- Loses things necessary for tasks (books, pencils, toys)
- Easily distracted by extraneous stimuli
- Forgetful in daily activities
Hyperactivity-Impulsivity Symptoms
- Fidgets, squirms in seat
- Leaves seat when expected to remain seated
- Runs about or climbs excessively
- Difficulty playing quietly
- 'On the go' or acts as if 'driven by a motor'
- Talks excessively
- Blurts out answers before questions are completed
- Difficulty waiting turn
- Interrupts or intrudes on others
Comorbidities (present in ~65% of ADHD)
- Oppositional defiant disorder (~40%)
- Conduct disorder (~15%)
- Anxiety disorders (~25-30%)
- Specific learning difficulties (dyslexia, dyscalculia ~25%)
- Autism spectrum disorder (~20%)
- Tic disorders/Tourette syndrome (~10%)
- Sleep disorders
Red Flags
- Severe behavioural disturbance with risk to self or others — urgent specialist referral
- Cardiac symptoms on stimulant medication (palpitations, chest pain, syncope) — stop medication, cardiology review
- Significant weight loss on medication
- Psychotic symptoms — reassess diagnosis and medication
- Suicidal ideation — particularly with atomoxetine
Differential Diagnosis
| Diagnosis | Key Features | Investigation |
|---|---|---|
| ADHD | Pervasive, >2 settings, onset <12 years, functional impairment | Clinical assessment, rating scales |
| Normal childhood behaviour | Age-appropriate activity levels, no impairment | Developmental assessment |
| Anxiety disorder | Worries, somatic symptoms, avoidance, may cause inattention | Clinical, anxiety rating scales |
| ASD | Social communication difficulties, restricted interests, sensory issues | Developmental assessment |
| Specific learning difficulty | Academic difficulties in one domain, not pervasive | Educational psychology |
| Attachment disorder | Disinhibited or reactive, history of neglect/trauma | Developmental history |
| Hearing or visual impairment | Inattention due to sensory deficit | Audiometry, visual acuity |
| Absence epilepsy | Brief staring episodes, EEG abnormality | EEG |
| Thyroid disorder | Hyperactivity, weight change, tremor | TFTs |
Diagnosis / Investigation
Bedside
- Comprehensive clinical assessment: Developmental history, school reports, observation across settings
- Validated rating scales: Conners' Rating Scales, Strengths and Difficulties Questionnaire (SDQ), SNAP-IV — completed by parents AND teachers
- Physical examination: Cardiovascular (murmurs, BP, HR), neurological, growth parameters
- Developmental assessment: Cognitive, language, motor skills
Bloods
- Not routinely required for ADHD diagnosis
- Pre-medication baseline: Height, weight, BP, HR (NICE NG87)
- TFTs: If clinical suspicion of thyroid disorder
- ECG: Only if personal or family history of cardiac disease, sudden death, or abnormal cardiac examination
Imaging
- Not required for ADHD diagnosis (neuroimaging findings are research tools, not diagnostic)
Special Tests
- Educational psychology assessment: If co-existing learning difficulties suspected
- Neuropsychological testing: May aid characterisation (not required for diagnosis)
- Sleep assessment: If significant sleep disturbance (common in ADHD)
Management
Non-pharmacological
- First-line for all ages (NICE NG87): ADHD-focused group parent training programme (e.g., Triple P, Incredible Years)
- Environmental modifications: Preferential seating, structured routines, clear instructions, break tasks into smaller steps
- Behavioural strategies: Positive reinforcement, visual timetables, reward charts
- School support: Educational Health Care Plan (EHCP) or SEN support if needed
- CBT: For comorbid anxiety or emotional dysregulation in older children
- Exercise: Regular physical activity may improve symptoms
Pharmacological
- First-line ≥5 years: Methylphenidate
- Immediate-release: 5mg BD-TDS, titrate weekly by 5-10mg increments; max 60mg/day (in divided doses)
- Modified-release: Concerta XL 18mg OD, titrate to max 54mg OD; or Medikinet XL, Equasym XL
- Second-line: Lisdexamfetamine 20mg OD, titrate to max 70mg OD (if methylphenidate inadequate/not tolerated)
- Third-line: Dexamfetamine 2.5-5mg BD, titrate to max 20mg/day; or atomoxetine (non-stimulant, noradrenaline reuptake inhibitor) 0.5mg/kg/day for 7 days, then 1.2mg/kg/day
- Guanfacine (Intuniv): α2A-adrenergic agonist; licensed for ADHD in children ≥6 years; consider if stimulants not tolerated or with comorbid tics
- Monitoring on medication: Height, weight (plotted on growth chart), HR, BP every 6 months; annual medication review with trial of dose reduction
Surgical/Interventional
- Not applicable
Referral Criteria
- Suspected ADHD — refer to specialist (paediatrician, child psychiatrist, or specialist ADHD service) for diagnostic assessment
- Only specialists should initiate ADHD medication (NICE NG87)
- Shared care arrangements with GP once stable
Prognosis
- Persistence: ~65% of children with ADHD continue to have significant symptoms in adulthood
- Academic: Children with untreated ADHD are more likely to underperform academically; 30-40% have a specific learning difficulty
- Medication response: ~70% of children respond to first-line methylphenidate; ~90% respond to at least one stimulant
- Driving: Increased risk of road traffic accidents; stimulant medication reduces this risk
- Substance misuse: Untreated ADHD increases risk; treatment with stimulants does NOT increase substance misuse risk (may be protective)
- Quality of life: Significant improvement with appropriate treatment (medication + behavioural strategies)
Other Relevant Information
DSM-5 Diagnostic Criteria Summary
| Criterion | Detail |
|---|---|
| Symptoms | ≥6 inattention and/or ≥6 hyperactivity-impulsivity symptoms (≥5 for age ≥17) |
| Duration | ≥6 months |
| Onset | Several symptoms present before age 12 |
| Settings | Present in ≥2 settings (home, school, work) |
| Impairment | Clear functional impairment |
| Exclusion | Not better explained by another mental disorder |
ADHD Medication Comparison
| Medication | Class | Onset | Duration | Key Side Effects |
|---|---|---|---|---|
| Methylphenidate IR | Stimulant | 30 min | 3-4 h | Appetite suppression, insomnia, headache |
| Methylphenidate MR (Concerta XL) | Stimulant | 1 h | 12 h | As above |
| Lisdexamfetamine | Stimulant (prodrug) | 1.5 h | 13 h | As above, less abuse potential |
| Atomoxetine | Non-stimulant (NRI) | 2-4 weeks | 24 h | GI upset, suicidal ideation (rare), hepatotoxicity (rare) |
| Guanfacine MR | Non-stimulant (α2A agonist) | 1-2 weeks | 24 h | Sedation, hypotension, bradycardia |