4 October 2024
Definition
ADHD or attention deficit hyperactivity disorder, is a neurodevelopmental disorder characterised by persistent patterns of inattention, hyperactivity and impulsivity.
Prevalence
ADHD effects approximately 5 to 7 percent of children and 2 to 5% of adults worldwide
Impact
ADHD can lead to significant impairment in academic, occupational and social functioning if left untreated
Historical context and evolution of ADHD diagnosis
Early descriptions
Symptoms similar to ADHD were first describing medical literature in the late 18 century. Sir Alexander Crighton mentioned “mental restlessness” in 1798
20th Century
The term “minimal brain dysfunction” was used in the 1930s to 1950s. The first use of “hyperkinetic impulse disorder” appearing the DSM-II 1968
Modern diagnosis
The DSM-III (1980) introduced ADD with or without hyperactivity. The DSM-IV (1994) and the DSM-V (2013) refined criteria to the current understanding of ADHD
Symptoms
Inattention
- Fails to give close attention to details/careless mistakes
- Difficulty sustaining attention
- Does not appear to listen
- Does not follow through on tasks
- Poor organisation
- Forgetful in daily activities
- Avoids sustained mental effort
- Loses things
- Easily distracted
Hyperactivity
- Fidgeting
- Inability to stay seated
- Running or climbing inappropriate situations
- Play or take part in activities quietly
- On the go “driven by a motor”
- Talking excessively
Impulsivity
- Blurting out answers before questions completed
- Difficulty awaiting return
- Interrupts or intrudes on others
3 or more present before 12 (and or A) 5 or more in adulthood
Additional diagnostic criteria
Pervasiveness
Symptoms must be present in multiple settings e.g. school, home, work, leisure
Severity
Symptoms most significantly impair functioning in the different settings
Exclusion of other disorder
Symptoms are not better accounted for by other psychiatric disorders e.g. mood disorder, anxiety disorder, learning disability
The genetics…
- Heritability estimates around 70 to 80%
- Numerous genes implicated
- Largely genes relating to dopamine and serotonin pathways
- DRD4 (Dopamine post synaptic activity)
- DAT1 (Dopamine presynaptic reuptake)
- SLC6A3 (Serotonin presynaptic reuptake)
Models for understanding ADHD
Medical
- A disorder that can be helped by treatment
- ADHD as a pathology
Social
- People are disabled by barriers in society, not their impairment/difference
Neurodiversity
- People have brains that work differently, just a natural human variation
- Accepts neurodevelopment conditions as different ways of thinking and behaving
The neurobiology bit…
Brain regions involved
Key brain regions implicated in ADHD include the prefrontal cortex, basal ganglia and the cerebellum. These areas are associated with executive function motor control and attention regulation.
Neurotransmitter system
Dopamine and norepinephrine are the primary neurotransmitters involved in ADHD abnormalities in these systems contribute to the symptoms of inattention, hyperactivity and impulsivity.
Brain activity (fMRI and PET scans)
- Hypoactivity in prefrontal cortex
- Hyperactivity in the default more network
Structural differences (MRI)
- Reduced volume in prefrontal cortex, basal ganglia and cerebellum
PFC- Exec function | BG_ Motor control | Ceri- Attention regulation
Or an interplay between Networks…
Default Mode Network
- Primarily active at rest
- Internally focused
- Daydreaming, recalling memories, planning for the future
- Self referential and introspective
- Medial prefrontal cortex (mPFC)Posterior cingulate cortex (PCC) and angular gyrus
Task-Positive Network
- Goal directed
- Externally focused
- Tasks requiring attention active problem-solving
- Task specific
- Dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex
Default Mode Network and Task-Positive Network
Salience Network (Conductor)
- Detects and filters relevant stimuli (internal and external) and as such switches between DMN and TPN
- Anterior insula and anterior cingulate cortex
Guidelines
NICE last updated 2019
- Meds only if modifications don’t impact at least one domain
- Non pharmacology
- Support
- CBT
- Regular review
- Methylphenidate or Lisdexamphetamine first line
- Dexamphetamine if Lis’ works but intolerable
- Atomoxetine if others fail/intolerable
Stimulants Acting on dopamine
*Methylphenidate (Concerta, Ritalin)
Can be released in different forms
*Lisdexamfetamine (Elvanse)
Prodrug with metabolite Dexamphetamine
Dexamfetamine(Dexedrine)
Immediate release
Nonstimulant Acting primarily on noradrenaline
Atomoxetine
Half of the effect in first week the overall effect in 2 to 3 months
Guanfacine
*First Line
Nonpharmacological treatments
Preschool and younger children
- Parent-child interaction therapy (PCIT)
- Behavioural parent training (BPT)
- Group parenting programs
- Online resources and workshops
- PCIT–teachers parents specific skills to improve their child’s behaviour and enhance the parent-child relationship
- BPT–focuses on teaching parents techniques to reinforce positive behaviours and reduce problematic ones
- Parenting programs–provide supportive environment for parents to learn and share experiences
- Online resources and workshops–accessible tools and information to help parents manage ADHD at home
Adolescents and adults
- CBT
- Social skills training
- Parenting programs
- Mindfulness and relaxation techniques
- Evidence is limited but studies focus the outcome on reducing symptoms
- CBT–focus on changing negative thought patterns and behaviours associated with ADHD
- Social skills training–helps individuals with ADHD improve social interactions and relationships
- Parenting programs–educate parents and effective strategies to manage their child’s ADHD symptoms
- Mindfulness and relaxation–incorporate mindfulness practices to improve attention and reduce stress
Diet, exercise and lifestyle
Exercise
- Little evidence
Diet
- Omega-3 supplementation- limited effect
- Restricting synthetic food colouring–small reduction in symptoms
- Reducing sugar intake and general improving diet–effect on inattention symptoms, weaker for hyperactivity impulsivity
Adaptations
- Others accommodating differing needs
- Think about seating arrangements, changes to lighting and noise, reducing distractions e.g., using headphones, optimising work or education to have shorter periods of focus and movement breaks, and reinforcing verbal requests with written instructions.
The future
- Advances neuroimaging should provide the better insights into the disorder’s pathophysiology
- Clearer biomarkers to provide more specific treatment
Potential new treatments
- Neurofeedback (promising with fMRI, limited with EEG)
- Trigeminal nerve stimulation (promising)
- Brain stimulation (little evidence)
Author
By Christer Nicholson, (Mental Health Advanced Clinical Practitioner at Stockport Early Interventions team).
This blog is simply to provide information, any further guidance should be sought through a GP or appropriate services.