What is the heritability of autism?
80-90%
What is the heritability of ADHD?
60-90%
What is the triad of ADHD?
- Inattention
- Hyperactivity
- Impulsivity
What are the ICD-11 criteria for ADHD?
- Symptoms lasting >6 months
- Inattention and/or hyperactivity-impulsivity
- Pervasive across different situations (eg. at home and at school)
- Onset <7 years (may be early signs of milestone delays etc)
- Significant distress or social impairment
What is the epidemiology of ADHD?
- ~5% of the population
- M:F 3:1
- Comorbidities
Which comorbidities is ADHD associated with?
- Oppositional defiant disorder (50%)
- Conduct disorder (25%)
- Learning difficulties (30%)
- Anxiety disorder (25%)
- Depressive disorders (15%)
What is the ADHD spiral?
What is the link between prefrontal dysfunction and ADHD?
- MRI indicates reduced PFC size and blood flow to PFC in ADHD patients
- ADHD patients demonstrate poor performance on executive function tasks
- ADHD patients demonstrate underfunctioning of dopamine system: DRD4 (receptor), DAT1 (transporter)
What executive functions can patients with ADHD struggle with?
- Planning & flexible strategy
- Impulse control
- Orient to salient stimuli & adjust action
- Suppress inappropriate actions in favour of appropriate ones
Which test can be used to assess executive function?
- Wisconsin card sorting test
- Stroop test (tests distractibility by other stimuli)
What is the stroop test?
What are the non-genetic biological aetiologies of ADHD?
- Prematurity
- Very low birth weight
- Foetal alcohol syndrome
- Associations between some food additives and childhood hyperactivity
What are the parental factors that influence ADHD?
- Increased critical comments/ maltreatment/ physical discipline
- Decreased sensitivity to the child’s needs
- Maternal depression
What is the conservative management of ADHD?
- CBT
- Psychoeducation
- Parental skills training
- Determine whether individuals are sensitive to specific food groups and modify diet appropriately
What is the medical management of ADHD?
Medication readdresses PFC underactivity
Stimulant:
- Methylphenidate (Ritalin, Concerta XL)
Non-stimulant:
- Atomoxetine (Noradrenaline reuptake inhibitor)
What is the mechanism of methylphenidate?
- Blocks the noradrenaline reuptake transporters
- Blocks the dopamine transporter (DAT)
- Acts as an agonist for the post-synaptic dopamine receptor D4 (DRD4)
What is the onset of methylphenidate action?
1-3 hours (rapidy absorbed and quick acting)
In which patients is methylphenidate recommended?
In severe/ moderate cases of ADHD where psychological interventions have failed
What are the common side effects of methylphenidate?
- Aggression/ hostility
- Decreased appetite
- Sleep disorders
- GI discomfort
What are the less common side effects of methylphenidate?
- Cardiac arrythmia: baseline ECG and pulse if high risk
- Hypertension: monitor BP
- Anorexia and growth suppression: monitor height and weight (growth chart in CAMHS, BMI in adults)
- Tics
What are the second line medications for ADHD?
- Dexamfetamine/ Lisdexamfetamine (Adderall)
- Guanfacine
- Atomoxetine
What is the moa of Dexamfetamine/ Lisdexamfetamine?
Stimulants
- Careful titration
- Close monitoring for cardiac arrythmia, hypertension, anorexia
What is the mechanism of Guanfacine?
- Alpha-adrenergic receptor agonists (non-stimulant)
- Can reduce tics
- Side effects: anxiety, decreased appetite, GI
What is the mechanism of atomoxetine?
- Antidepressant: NARI (non-stimulant)
- Little - no insomnia, no increase in tics
- May help comorbid depression
- Used if concern about stimulants
- S/e: decreased appetite, GI, fatigue, probable mild growth slowing, slower to work
