ADHD in Children

❍ At a glance

• ADHD affects approximately 5-8% of school-age children in NZ.¹ It is frequently under-diagnosed in girls (who more often present with the inattentive subtype without hyperactivity) and over-diagnosed when difficulties are better explained by anxiety, trauma, or learning disabilities.
• DSM-5 requires ≥6 symptoms of inattention and/or hyperactivity-impulsivity present in at least two settings, causing functional impairment, with onset before age 12, and not better explained by another disorder.²
• In NZ, stimulant prescribing in children under 16 requires specialist initiation. Once stable on treatment, ongoing prescribing and monitoring can be managed in general practice.
• Methylphenidate is first-line and subsidised under Special Authority (specialist-initiated in under 16s). Common dose-dependent side effects: appetite suppression and sleep disturbance. Monitor height, weight, blood pressure, and heart rate regularly.

❍ Presentation and clinical assessment

DSM-5 criteria require: six or more symptoms of inattention and/or hyperactivity-impulsivity (five or more in adolescents aged 17+); symptoms present in at least two settings; evidence of functional impairment; symptom onset before age 12; symptoms not better explained by another mental disorder.² Inattentive symptoms include: difficulty sustaining attention, frequent careless errors, not seeming to listen when spoken to, failing to follow through on instructions, difficulty organising tasks, being easily distracted, and forgetfulness. Hyperactive-impulsive symptoms include: fidgeting, leaving seat, running or climbing inappropriately, excessive talking, blurting out answers, difficulty waiting for a turn, and interrupting others.

Clinical assessment involves: structured interview with parents and the child; review of school information (teacher report); use of validated rating scales (Conners 3 or Vanderbilt ADHD Rating Scales, with both parent and teacher forms); assessment of comorbidities (anxiety, learning difficulties, ASD, oppositional defiant disorder, sleep disorder); review of developmental history; hearing test to exclude hearing impairment as a contributor to inattention. Symptoms must be present across settings - a child who is attentive at home but distractible only at school may have a situational rather than neurodevelopmental explanation.

There is no diagnostic blood test, imaging, or neuropsychological test that confirms ADHD. The diagnosis is clinical. Thyroid function and FBC may be relevant if the clinical picture suggests an underlying medical cause; formal neuropsychological testing is useful if a learning disability is suspected alongside ADHD but is not required for the ADHD diagnosis itself.

❍ Management

Non-pharmacological: parent training programmes (Triple P, Circle of Security) have good evidence for improving behaviour and reducing family stress. School-based accommodations (extra time, seated near the front, task chunking, movement breaks) are important and the GP can support the family in advocating for these. Regular physical activity has a meaningful effect on ADHD symptoms. Adequate sleep is critical - many children with ADHD have sleep difficulties which exacerbate inattention.

Pharmacological: methylphenidate (Ritalin, Rubifen, Concerta) is first-line and subsidised in NZ under Special Authority criteria requiring specialist initiation in children under 16. It is a dopamine and noradrenaline reuptake inhibitor with robust evidence for improving attention and reducing hyperactivity.³ Starting doses are low (typically 2.5-5 mg for immediate-release), titrated slowly; most children require dose adjustment over the first weeks to months. Common and dose-dependent side effects: appetite suppression and sleep disturbance. Regular monitoring of height, weight, blood pressure, and heart rate is required.

Alternatives where methylphenidate is not tolerated or insufficiently effective: dexamfetamine (Dexedrine), atomoxetine (Strattera), or guanfacine (Intuniv) for children with prominent hyperactivity-impulsivity - all initiated by specialists.

❍ GP monitoring and referral

Once stable on treatment, the GP typically manages 3-6 monthly reviews covering: symptom control (parent and teacher feedback), growth (plot on chart), blood pressure and heart rate, sleep quality, mood and appetite, and any emerging side effects. Annual specialist review is recommended. Medication holidays over school holidays are sometimes considered where appetite suppression or growth velocity is a concern - discuss with the specialist.

Refer to paediatrics or child psychiatry for: initial ADHD assessment where the diagnosis is uncertain; the child is under 5; there are significant comorbidities (ASD, anxiety, conduct disorder, learning disability); or stimulant prescribing is being considered. In NZ, referral is required before initiating stimulant medication in children under 16.