ADHD Flashcards
What are the main clinical features of ADHD?
- Inattention
- –Poor organisation/planning
- –Poor response inhibition
- –Poor impulse control - Hyperactivity
- –Disorganised
- –Poorly controlled
- –Restless/fidgety - Impulsivity
- –Poor awareness of danger
- –Accident prone
- –Social disinhibition
- –Emotional dysregulation (e.g. anger, extreme emotions)
List some comorbidities of ADHD.
- Sleep disorders (50%)
- Behavioural difficulties (25-50%)
- Specific learning diabilities (25%)
- Developmental coordination disorders (25%)
- Social communication difficulties (25%)
- Anxiety symptoms (20%)
- Tic disorders (20%)
- Mood difficulties (20%)
- Increased psychosocial factors
Describe the prevalence of ADHD (including gender differences).
1-5% population officially (0.4% in Scotland/Glasgow)
Male:female ratio in children: 4:1
Male:female ratio in adults: 1:1
Describe the causes of ADHD.
- Risk factors
- –Boys
- –Poverty
- –Lead exposure
- –Iron deficiency
- –Maternal alcohol during pregnancy - Genetics
- –Dopamine receptor 4 and 5
- –Dopamine transporter
- –Dopamine beta hydroxylase
- –Serotonin receptor 1B
- –Serotonin transporter
- –Synaptosomal associated protein 25 - Environment
- –Low socioeconomic class
- –Low birth weight
- –Maternal smoking
- –Psychosocial adversities - Organic factors
- –Smaller brain volume
- –Smaller basal ganglia
- –Smaller cerebellar vermis
Describe the different subtypes of ADHD, and their prevalence.
- Inattentive ADHD (20-30%)
- –Presents later in adolescence
- –Failure to follow instructions
- –Careless mistakes
- –Forgetfulness
- –Poor organisation
- –Academic difficulties - Hyperactive ADHD (15%)
- –Presents earlier in childhood
- –Running around
- –Frequently interrupts
- –Restlessness
- –Disruptive behaviour - Combined ADHD (50-75%)
- –Meets criteria for both types of ADHD - Unspecified ADHD
- –Significant impairment which does not fit the criteria for either type of ADHD
Describe the pathophysiology of ADHD. (12 marks)
- BRAIN NEUROCHEMISTRY
a) Dysfunction of dopamine/noradrenaline pathways in the prefrontal cortex
- –Dopamine: mesocortical pathway (function: on-task behaviour/cognition, focus)
- –Noradrenaline: locus ceruleus pathway (function: dampens extraneous stimuli, executive operations, response inhibition)
b) Hypoarousal
- –Loss of dopamine/noradrenaline in the arousal network of the prefrontal cortex
- –This means that extraneous information is no longer filtered - leads to inattention
- –This means that there is no response inhibition of other brain areas - leads to hyperactivity and impulsivity
c) Hyperarousal
- –Loss of response inhibition from PFC leads to hyperactivity and impulsivity
- –Signal:noise detection ratio decreases, i.e. inappropriate stimuli can’t be filtered out, which leads to increased activation of receptors - leads to inattention
- BRAIN NEUROPSYCHOLOGY
a) Poor executive function (e.g. organisation, planning) - CHANGES IN BRAIN STRUCTURE
a) Decreased brain volume in certain areas, e.g.
- –Cerebellum
- –Basal ganglia
- –Total cerebrum
- –Right cerebrum
- –Prefrontal cortex
- –Corpus callosum
- –Right caudate
- –Reduced white/grey matter
Outline the treatment options (in order of priority) for ADHD.
- Environmental interventions
- Behavioural interventions
- Psychostimulants (methylphenidate, dexamphetamine)
- Atomoxetine
- Alpha adrenergic agonists (clonidine, guanfacine)
- Anti-depressants (TCAs, MAOIs)
- Dopaminergic drugs (modafinil)
What are the mechanisms of action for the 2 main psychostimulants used to treat ADHD?
Methylphenidate:
1. Blocks the dopamine transporter, i.e. inhibits dopamine reuptake
Dexamphetamine:
- Blocks the dopamine transporter, i.e. inhibits dopamine reuptake
- Facilitates dopamine release from presynaptic storage vesicles
List some side effects of psychostimulants in ADHD treatment.
- Misuse of dexamphetamine (controlled substance)
- Increased BP/heart rate
- Sleep difficulties/insomnia
- Anorexia
- Loss of appetite
- Growth retardation
- Sadness
- Irritability
- Abdominal pain
- Headaches
Describe the mechanism of action of atomoxetine.
- Noradrenaline reuptake inhibitor
2. Focussed on prefrontal cortex - avoids rewards pathway, so there is no risk of addiction
What are the advantages of atomoxetine as compared to psychostimulants?
- Long half life (once a day dosing)
- No abuse
- No drug holidays needed
- Effective for comorbidities too
List the side effects of atomoxetine. Which are the 3 most significant ones?
- Mood swings (e.g. rage)
- Suicidal tendencies
- Hepatic impairment
- Nausea/vomiting
- Abdominal pain
- Weight loss
- Headaches
- Excessive tiredness/insomnia
- Constipation
- Increased HR/BP
What is the mechanism of action of adrenergic drugs in ADHD treatment?
Alpha adrenergic agonists bind to noradrenaline receptors in the prefrontal cortex and stimulate them
What are the side effects of adrenergic drugs in ADHD treatment?
- Sedation
- Dizziness
- Hypotension
What are the side effects of anti-depressants in ADHD treatment?
- Anticholinergic effect
- Cardiac effects
- Seizures