ADHD Flashcards
What does ADHD stand for and symptoms?
Attention Deficit Hyperactivity Disorder: impacts ability to focus, regulate activity levels andcontrol impulses.
Due to this, hard to diagnose in young children/must have severe symptoms.
ADHD lifetime prevalence
3-5% of school aged children
What are the 2 primary clusters of symptoms and what do they lead to?
1) Inattentiveness: difficulty concentrating.
2) Hyperactivity and impulsiveness
Underachievement in school, poor social interaction, discipline problems.
State inattentiveness symptoms
Short attention span, careless mistakes, forgetful/losing things, enable to stick to tasks that are tedious, appearing enable to listen, constantly changing activity or task, difficulty organising.
State Hyperactivity and impulsiveness symptoms
Unable to sit still, fidgeting, unable to concentrate on tasks, excessive physical movement, talking, unable to wait, impulsive, interrupting, little sense of danger.
Outline sex differences
Higher prevalence in boys (up to 16:1)
However, thought underdiagnosed in females due to difference in presentation and better masking.
Females: internalising behaviours such as anxiety
Males: hyperactivity
Outline diagnosis of ADHD
10 week period of watchful waiting: see if symtoms change.
If no improvement - referal to specialist, detailed assessment.
Must have 6+ of each of diff clusters for over 6 months.
No one official test:
Continuous Performance Task (CPT): Press quickly for every letter except the X, prolonged sequence (~15 mins).
ADHD will have greater variation in response timing, greater errors.
Errors of omission (failing to press when you should)
Disengagement / inattentiveness
Errors of commission (pressing when you should not)
impulsivity
What are the different types of ADHD?
1) Hyperactive
2) Inattentive
3) Combined
People often given one of these classifications that can change over lifespan. Different types - develop tailored treatment plan.
Hidden symptoms of ADHD?
Poor sleep, easily bored, OCD, anxiety, depression, forgetting to eat, difficulty maintaining relationships.
Positive traits of ADHD?
can see negatives as positives: energetic, eager, spontaneous, sensitive, creative and persistent.
Aetiology?
Complex
Genetic: 60-90% heritability, ADHD associated mutations.
Environmental: perinatal difficulties, iron deficiency, psychological adversities, chemical contamination =
poor maternal nutrition/anaemia, parental psychopathology, lower socioeconomic status, complicated pregnancy, prematurity, low birth rate…
NB: environmental risk factors interact with genetic vulnerabilites.
How is ADHD brain different?
Reduction in grey matter: cortical thinning and delayed maturation
Outline genes linked to ADHD
Dopamine reuptake transporters, serotonin receptors/transporters etc and other neurotransmitter linked proteins.
These linked to…
Attention, behaviour, emotion, memory, learning, cognition, posture and speech.
Cormobidities
75% of patients have at least one comorbid condition.
Depression, bipolar, anxiety disorders, conduct disorder (impulsive), oppositional defiant disorder (argumentative)…
NB: One of the above conditions can make ADHD hard to diagnose, mask. Genetic makeup that causes risk of ADHD also increases risk of mood disorders.
Brain structures linked to ADHD
PFC: attention, working memory etc.
ACC: movement, attention, emotion.
Cerebellum: motor control, cognitive and affective processes.
Parietal cortex: orientation of attention.
Basal ganglia: motivation, reward processing, goal-directed behaviour.
Brain networks in ADHD
Cognitive-Executive Network: executive function, working mem, selective and sustained attention.
Cortico-Striatal-Thalamic-Cortical Network: assigning salience, motivation and inhibition of inappropriate actions.
Cortico-limbic network: emotional dysregulation and deficits in impulsivity and motivation.
Neurotransmitters involved in ADHD
DA, NA (noradrenaline), 5-HT, GABA, Glu
Dopamine abnormalities
Increased DAT binding in up to 70% children and adults diagnosed with ADHD (higher density of DAT in brains).
DA neurons respond differently: cued learning responses abnormal.
Catecholamines
Regulate PFC: Too little NA and DA, underactive.
Management of ADHD
First line: non-medication, parent training programmes, behavioural management, attention training.
Second line: only given if symptoms persist. Monitored continuously and may be switched.
Pharmaceutical drugs
Methylphenidate: stimulant that slowly increases level of catecholamines in brain. Lowest effective dose should be used.
Similar to abused drugs.
Cocaine: low doses hyperactivity and narcolepsy, local anaestheic, pupil dilation via na channel block
Cocaine DA
Inhibits DAT
Amphetamine DA
pumped into nerve terminals via actions of DAT and disrupts vesicular storage of monoamines.
Monoamines (DA) pumped into nerve terminals by reverse action of transporter (DAT)
Methylphenidate DA
Works in same way as cocaine and amphetamine
Mesocorticolimbic system
All addictive drugs activate this system as does methylphenidate.
Therefore, taken orally so longer to reach brain and at doses that make less dangerous.
methylphenidate and network activity
Single dose: decreases ACC and increased right inferior frontal gyrus.
methylphenidate side effects
Decreased appetite, restricted growth, increased bloop pressure and heart rate, tics, drowsiness etc.
Effect of stimulants on adhd and neurotypical
Decreases motor activity in both.
Increases working memory in both.
Genetic model
DAT KO: hyperactivity, deficits in spatial memory.
Decrease in D2 receptors in basal ganglia (not seen in humans, you would think this would inhibit hyperactivity)
Trauma model
Maternal stress: hyperactivity induced, but no data on impulsivity etc…
Reward processing messed up
There is reduced spike in dopamine when think about rewarding behaviour, no motivation to do hard tasks etc
Kofler et al., 2015:
Kofler et al., 2015: ADHD people fidget more when task gets harder
Fritz et al., 2016:
Fritz et al., 2016: 32 Men with ADHD performed better on tests after exercise (also improves mood)
McGough et al., 2019:
McGough et al., 2019: studies suggest that eTNS stimulates the cranial nerves in the forehead, which in turn stimulate various brain areas implicated in ADHD such as the anterior cingulate, insula, and frontal lobes = areas associated with executive function.
52% of children have a significant reduction in symptoms.
FDA approved non drug, worn at night.
