Attention-Deficit/Hyperactivity Disorder – Comprehensive Study Notes

DSM-5 Classification & Core Criteria

• ADHD is grouped under Neurodevelopmental Disorders alongside autism, intellectual disability, etc.
• Shared attributes of neurodevelopmental disorders
  • Childhood onset
  • Atypical development of core skills that usually emerge gradually (motor, language, social, self-regulation)
  • Persist, in some form, into adulthood
  • Impair personal, social, academic, occupational functioning
  • High rates of co-occurrence with each other
• DSM-5 conceptualises ADHD through three symptom clusters
  1. Inattention (more accurately “dysregulated attention”)
  • Wanders off task, lacks persistence, easily distracted
  • Disorganisation, loses things, forgetful
  1. Hyperactivity
  • Excessive motor activity when inappropriate
  • Fidgeting, tapping, running/climbing, talkativeness
  1. Impulsivity
  • Hasty acts without forethought; seeks immediate reward
  • Difficulty delaying gratification; social intrusions (blurting, interrupting)
• Diagnostic thresholds (observable behaviour only)
  • $\ge 6$ inattentive and/or $\ge 6$ hyperactive–impulsive symptoms for $\ge 6$ months (children ≤ 16 yrs)
  • Adults (≥ 17 yrs): $\ge 5$ symptoms in either/both clusters
  • Several symptoms must have been present before age 12
  • Symptoms present in ≥ 2 settings (home, school, work, social)
  • Must cause clinically significant impairment
  • Cannot be better explained by oppositionality, comprehension failure, hostility, or other disorders
• Presentation specifiers
  • Combined (both thresholds met)
  • Predominantly Inattentive
  • Predominantly Hyperactive/Impulsive
• Severity specifiers (mild, moderate, severe)
  • Consider total symptom load, degree of functional impairment, comorbidity
• Contextual caveat
  • High-reward, novel, or 1-to-1 environments can mask symptoms
  • Boring, low-structure, low-stimulation settings exacerbate them
  • Lack of cross-situation symptoms ≠ absence of ADHD

Developmental Manifestation Across the Lifespan

Preschool (≤ 5 yrs)

• Short play sequences, incomplete activities, non-listening
• Little sense of danger, constant motion, scant sustained attention
• High false-positive risk: typical toddlers are naturally impulsive and active
• Subtle early markers often missed; environment still low-demand

Primary School (≈ 6–11 yrs)

• Classroom expectations expose deficits: sitting, concentrating, self-management
• Signs:
  • Forgetfulness, disorganisation, distractibility
  • Excessive restlessness, blurting, rule-breaking accidents
  • Academic under-achievement; behavioural issues; peer problems
  • Elevated teacher/parent stress

Adolescence (12–17 yrs)

• Transition to self-management (timetables, homework, multiple classrooms)
• Previously compensated children may “fall apart” academically & socially
• Manifestations:
  • Missed details, scheduling failures, poor foresight & risk taking
  • Car or DIY accidents; impulsive money/drug/alcohol behaviours
  • Emerging self-medication reports

Adulthood (18 yrs +)

• Inattention: bills, deadlines, appointments
• Continued impulsivity/hyperactivity (restlessness, job-hopping, driving offences)
• Mood, anxiety and substance disorders common (see Comorbidity)
• Poorly managed adults often describe lifelong compensatory strategies or illicit stimulant use

Differential Diagnosis & Cultural/Gender Issues

• Girls often less hyperactive → later/under-diagnosis
• Cultural norms: some societies expect early exuberance, later academic endurance
• ESL learners: inattentive appearance may be language processing fatigue
• Lack of conventional schooling, refugee trauma, or sensory overload can mimic ADHD
• Must rule out / distinguish from:
  • Oppositional Defiant Disorder (ODD) – refusal, defiance vs. dysregulated attention
  • Anxiety disorders – worry-driven distraction & fidgeting via cortisol surge
  • Autism Spectrum Disorder (ASD) – core social-communication deficits, RRBs, sensory processing differences
  • Learning disorders, intellectual disability, trauma, sleep disorder, thyroid, etc.

ADHD vs. ASD Red Flags

• ASD-leaning indicators: fascination with repetitive movement, language regression, “savant-like” splinter skills
• ADHD can show apparent social/flexibility issues secondarily (impulsive behaviour, compensatory rigid routines)

Comorbidity Snapshot

• Children (RCH multidisciplinary sample, N = 132)
  • ODD $\approx 52\%$, Anxiety $23\%$, Learning disability $15\%$, Language disorder $14\%$, Mood $5\%$, ASD $3.8\%$, ID $3.8\%$, Conduct $2\%$; None $23\%$
• Adults: high rates of mood, anxiety, substance use, and emotionally dysregulated personality disorders

Prevalence

• Global childhood pooled estimate: $7.2\%$ (Thomas et al., 2015)
• Australian survey: most common childhood mental health condition > anxiety
• Adult prevalence declines with age; possible reasons
  • Symptom remission in subset
  • Historical under-recognition in older cohorts

Etiology: Interacting Mechanisms

Genetics

• High heritability: $h^2 \approx 0.88$ (clinical ADHD)
• More heritable than major depression; similar to bipolar/schizophrenia
• Multiple genes; dopaminergic pathways prominent (DRD4, DAT1, COMT, etc.)
• Single-gene syndromes (e.g.
  fragile X) explain only a small minority

Teratogens / Medical

• Fetal alcohol exposure → ADHD-like profile; spectrum from effects to full FASD

Environment & Epigenetics

• Prefrontal cortex sensitive to early environment (Bock & Braun)
• Risk contexts
  • Pathogenic care: neglect, institutionalisation, caregiver turnover
  • Early trauma, coercive parenting, low SES, parental mental illness
  • Escalating transactional processes: difficult temperament ↔ parental stress
• Always embedded within genetic backdrop (G×E)

Neurobiological & Cognitive Theories

Executive Dysfunction Theory

• ADHD symptoms stem from deficits in executive functions (EF): inhibition, working memory, planning, cognitive flexibility
• Evidence
  • Group-level EF task impairments
  • Reduced prefrontal & frontostriatal volumes/activity

Dopaminergic / Motivational Theory

• Baseline hypodopaminergia → low intrinsic motivation, reward seeking, delay aversion
• Stimulant efficacy & dopamine genes support model

Other Hypotheses

• Circadian rhythm disruption → mis-timed arousal & fatigue
• Alternative neurotransmitters (norepinephrine, serotonin, acetylcholine, etc.)

Pharmacological Interventions (Effect sizes in children ≈ adults > placebo)

Psychostimulants (first-line)

1. Methylphenidate (Ritalin, Concerta)
   • Dopamine & norepinephrine reuptake inhibitor
   • Short-acting (2–3 doses/day) & long-acting formulations
   • Low-dose therapeutic window; high doses → agitation, abuse potential
   • Common adverse: insomnia, appetite loss
2. Amphetamines (Adderall, Vyvanse)
   • Increase synaptic DA/NE via release & reuptake blockade
   • Similar benefits + side-effects (sleep, anxiety, headache, nausea)
   • Street amphetamine self-medication reported in undiagnosed adults

Non-stimulants

3. Atomoxetine (Strattera)
   • Selective NE reuptake inhibitor; raises PFC dopamine indirectly
   • Slightly smaller effect size; useful with comorbid anxiety
4. α-2A Agonists
   • Guanfacine XR (Intuniv) & Clonidine (Catapres)
   • Reduce sympathetic tone; sedative, hypotensive side-effects
   • Reserved for stimulant-intolerant or adjunctive use

Emerging / Off-label & Nootropics

• Modafinil/Armodafinil: wakefulness agents; mixed ADHD evidence
• Over-the-counter amino acids (tyrosine, phenylalanine, L-dopa precursors) – limited empirical support; popular in online communities

Long-term Considerations

• Stimulant effects attenuate over years → parallel skill-building essential

Psychosocial & Behavioural Interventions

School-Based

• Teacher psychoeducation about ADHD mechanisms (EF, dopamine, movement)
• Classroom adjustments
  • Frequent breaks, fidget tools, movement access
  • Reward systems (dojo points, token economies)
  • Pre-loading instructions; stepwise directions; minimise distractions
  • Seating: front, low-noise, clear sightlines
  • Pomodoro-style work/break cycles
• Curriculum/material simplification; assistive tech

Parent Training & Family Work

• Psychoeducation: reframe ‘lazy’ as biologically-based dysregulation
• Evidence-based programmes (Triple P, PMT, Incredible Years)
• Non-judgemental delivery; acknowledge parental burden & possible parental ADHD
• Home routines, visual schedules, apps (e.g.
  Trello, Habitica, Time-Timer)

Individual Skills & Therapies

• ADHD / Executive Function Coaching: routines, planning, externalising structure, reduce cognitive load
• Mindfulness: attentional control practice; adult utility > child
• CBT: targets comorbid anxiety, depression, self-esteem; adapt for shorter attention & high movement needs
• Exercise: regular moderate-vigorous activity lowers symptom severity
• Occupational Therapy / Sensory Integration
  • Identify hypo- vs. hyper-sensitivities (noise, touch, proprioception)
  • Provide sensory diets, weighted items, movement circuits

Technology-Focused

• Neurofeedback
  • Train $\theta/\beta$ ratio (↓ daydream waves, ↑ alertness waves)
  • Small adult evidence; motivation-intensive; scarce paediatric data
• Computerised Cognitive Training
  • Game-like sustained attention tasks with adaptive difficulty
  • Mixed transfer to real-world functioning; costly licences

Assessment Protocol

1. Clinical Interviews
   • Parent(s): prenatal, birth, developmental milestones, medical, temperament, family mental health, trauma, environment
   • Child/adolescent (developmentally adjusted): self-perception & difficulties
   • Teacher input essential
2. Rating Scales / Questionnaires
   • Connors-3: Inattention, Hyperactivity/Impulsivity, EF, Learning, Peer/Family
   • BASC-3: broad internalising, externalising, adaptive, EF
   • PLUS: SNAP-IV, ADHD-RS-5, Vanderbilt, BRIEF-2, SDQ
3. Direct Observation
   • Standardised testing session (clinic)
   • Classroom (primary years), playground, home videos
4. Performance Tests / Differential Screens
   • Cognitive/IQ + academic (WISC-V, WIAT-IV) to rule out LD/ID
   • Language, motor, sensory, sleep, medical investigations

Associated Clinical Features

• Sensory irregularities (hyper or hypo across modalities) – correlated with sleep problems
• Sleep: delayed sleep onset, nocturnal restlessness, daytime fatigue
• Hyper-focus capability: prolonged, intense immersion in high-interest tasks

Special Topic: Evolutionary Mismatch Theory

• Once-adaptive traits (rapid orienting to novel stimuli, high mobility) favoured survival in ancestral environments with:
  • Sparse sensory input
  • Need for vigilance (predation, foraging)
• Modern environments: information overload, sedentary schooling/work → same genes become maladaptive → symptomatic ADHD
• Discuss in tutorials: implications for stigma, intervention design, and societal expectations

Key Numerical References

• Diagnostic age criterion: symptoms pre-$12\text{ yrs}$
• Symptom threshold (child): $6 + 6$ or $6$ in one domain
• Adult threshold: $\ge 5$ symptoms
• Heritability $h^2 = 0.88$; Childhood prevalence $7.2\%$
• RCH comorbidity: only $23\%$ ADHD-only; ODD $52\%$

Practical Implications for Future Clinicians

• ADHD is heterogeneous; tailor assessments & interventions accordingly
• Combine medication with psychosocial supports; teach lifelong self-management
• Screen systematically for comorbidities; treat most impairing condition first
• Provide culturally & developmentally informed interpretations; avoid pathologising normal variability
• Frame interventions positively: enhance strengths (creativity, hyper-focus), minimise deficits (organisation, impulsivity)