PBL - ADHD Flashcards
When does brain remodelling occur and end?
It happens intensively around adolescence and continues into the mid 20s.
When is grey matter in the brain highest?
Early adolescence
What happens to the nerve cells age children age?
They get coated in myelin, increasing connectivity and affects how well different parts of the brain work together.
So there is an increase in white matter in the brain
Why are teenagers more likely to engage in impulsive and risky behaviour that adults?
Because the emotional amygdala has become fully developed, but the frontal cortex (responsible for keeping the emotional impulses in check) is still in maturity.
Also, the brain is still making synapses, refining brain pathways and myelinating axons. This means coordinated thought, action and behaviour are still developing
Why are teens more likely to be self-concious?
Hormones changes in the brain increases oxytocin production.
There is increased sensitivity to this in the limbic system, and it is linked to self-consciousness
What happens to the cortical grey matter in development?
It is pruned, and only the paths that we use often are retained
Summarise what happens during adolescent brain development.
CSF volume increases Cortex size decreases Cortical grey matter thins Increased white matter - myelinations Increased ventricle size Reduced number of neurons and connections
What are the two categories that the clinical features of ADHD can be split into?
Inattentiveness
Hyperactivity
List the inattentiveness symptoms of ADHD.
Short attention span
Careless mistakes
Forgetful or losing things
Can’t stick at tedious or time consuming tasks
Doesn’t listen or carry out instructions
Constantly changes activity
Has difficulty organising tasks
List the hyperactivity/impulsiveness symptoms of ADHD.
Can't sit still Fidgeting Unable to concentrate on tasks Excessive physical movement Excessive talking Unable to wait for turns Acts without thinking Interrupts conversations Little/no sense of danger
What are the symptoms of ADHD in adults?
Carelessness Lack of attention Always starting and nerve finishing tasks Lack of organisation Mood swings/anger Impatient Forgetful Excessive risk taking
What are the co-morbidities associated with ADHD in children?
Anxiety Depression Oppositional defiant disorder Sleep problems Autism Epilepsy Tourettes Learning difficulties
What are the possible genetic causes of ADHD?
DRD4 receptor - associated with hyperactivity and impulsivity
DAT1 - dopamine transport gene
DRD5 - dopamine receptor gene
5HTT - serotonin transport gene, associated with volatile emotions
HTR1B - serotonin receptor gene
What are the organic factors of ADHD?
Smaller brain volume - especially in the frontal and parietal cortex
Smaller basal ganglia
Reduced right dorso-lateral prefrontal cortex
List risk factors for ADHD.
Parents have it Genetics Premature baby - low birth rate Brain damage in early life Alcohol/drugs/smoking while pregnant Exposure to toxins at a young age
Briefly describe the pathophysiology of ADHD.
It’s a deficiency in the arousal mechanism
A defective inhibitory response found in a compromised pre-frontal cortex
- neurons in the PFC are out of tune, and cant filter the important external signals from the background noise
- all signals seem the same, causing lack of focus on any one thing
- insufficient information processing
Describe the hypo-arousal mechanism of ADHD.
Defective inhibitory response
Low tonic firing of dopamine/noradrenergic neurons
Treated with stimulants to amplify tonic firing rates
Describe the hyper-arousal mechanism of ADHD.
Excess noradrenergic/dopamine stimulates receptors and causes signals to noise detection to deteriorate
Associated with increased phasic firing of NA/D neurons
Treated by down-regulating neuronal activity and desensitise postsynaptic receptors
Describe some requirements for a diagnosis of ADHD to be made.
- apparent before the age of 7
- excessive for age and development
- pervasive
- symptoms worse in the afternoon
What are the SIGN guidelines for ADHD?
The core ADHD symptoms have a significant impact on the development of the child (impairs social, emotional and cognitive functioning)
Symptoms are responsible for morbidity and dysfunction of the child, peers and family
Name some things that should be recorded when taking a history of someone with suspected ADHD.
Current behaviour, activity levels, impulsivity, emotional reactivity Ability to sustain interest/attention Impact on child and family Interactions with others Eating and sleeping habits Parental management strategies
Name some of the things you should record in regards to medical history when examining someone with suspected ADHD.
Illness/infection Operations Head injury Hearing problems Tics/funny turns/faints/fits Current medication Allergies
What is the pharmacological treatment for ADHD?
1st line - psychostimulants (methylphenidate and dexamphetamine)
2nd line - atomoxetine
3rd line - clonidine
Describe the mechanism of action of dexamphetamine.
Blocks dopamine and noradrenaline membrane transporters, thus preventing re-uptake by pre-synaptic neurons
Also travels into the neuron and once inside it prevents noradrenaline/dopamine storage in vesicles
- increases cystolic concentrations and is transported back out into the synaptic cleft
