Week 9 - The neurobiology and management of ADHD Flashcards
What are the two main types of symptom in ADHD?
Symptoms that relate to attention and imulsivity/hyperactivity
As well as impairment in executive functions, what else do people with ADHD show impairments in?
- Selective attention
- Sustained attention
- Response precision
- Temporal information processing
What are the two main processses which can drive selective attention?
- Endogenous attention
- Exogenous attention
What is meant by the term selective attention?
The ability to process one stimulus in the presence of another potentially distracting stimuli
What are the two ways which selective attention may be driven?
- Exogenous (bottom-up)
- Endogenous (top-down)
What is exogenous attention driven by?
Sensory stimuli
What is endogenous attention driven by?
Internal goals or desires such as hunger
Where in the brain does the endogenous attention circuit begin?
The prefrontal cortex
Where in the brain does exogenous attention begin?
The sensory areas
Which type of attention is driven by a sensory stimuli such as a flash of light?
Exogenous attention
What is the key difference between exogenous and endogenous attention in terms of where the brain circuits begin?
Exogenous attention begins in sensory areas such as the visual cortex whereas endogenous attention begins in the prefrontal cortex
What does the superior calliculus play a role in?
- Receiving and processing sensory information
- Receiving projections from and sending projections to midbrain regions
Dysfunction in the superior calliculus may result in what difficulties?
Filtering the appropriate sensory stimuli from an otherwise overwhelming environment
What effect to the prefrontal cortex is noted in people with ADHD?
A reduction in volume
What is meant by myelination?
The process by which axons of neurons are coated in a fatty insulating substance called myelin
What is the purpose of myelination?
To speed up the conduction of action potentials
What abnormality to white matter has been noted in patients with ADHD?
A reduction in myelin
Which neurotransmitter is thought to be the most important for exogenous attention?
Acetylcholine
Which neurotransmitter is thought to be important for endogenous attention?
Dopamine
Name the three monoamine neurotransmitters
- Dopamine
- Serotonin
- Noradrenalin
What are the three principal dopaminergic pathways?
- Mesolimbic
- Mesocortical
- Nigrostriatal
As well as ADHD, what other conditions are dopaminergic pathways of interest regarding?
- Addictions
- Psychosis
What is the nucleus accumbens involved in?
Motivation
What is the nucleus accumbens of particular interest in the study of?
Addiction
Abnormalities within the serotonergic pathways are thought to be the basis of which condition?
Depression
What do serotonergic neurons play roles in?
- Sleep walking
- Emotions
- Moods
What is the hippocampus involved in?
- Learning
- Memory
- Emotion
- Mood
What are noradrenergic pathways most notably involved in?
- Arousal
- Reaction to stimuli
What are neurons that synthesise, store and release acetylcholine known as?
Cholinergic
What are cholinergic pathways involved in?
- Cognition
- Learning
- Memory
Cholinergic function is of particular interest with regards to the study of which condition?
Dementia
Where is the pons located?
The brain stem
Cognitive flexibility involves which 5 areas of the brain?
- Ventral tegmental area
- Prefrontal cortex
- Basal forebrain
- Amygdala
- Parietal cortex
Working memory involves which 3 areas of the brain?
- Ventral tegmental area
- Prefrontal cortex
- Locus coeruleus
Response inhibition involves which 3 areas of the brain?
- Basal ganglia
- Raphe nuclei
- Prefrontal cortex
Neurotransmitter is released from vesicles in the axon terminal into what?
The synaptic cleft
What does the neurotransmitter cross the synaptic cleft and bind to?
Receptors on the cell membrane of the postsynaptic neuron
Action potentials travel to the axon terminal in the what?
Presynaptic neuron
What are the methods by which neurotransmitter can be removed from the synapse?
- Reuptake
- Enzymatic degradation
- Diffusion
What does the gene which has been linked with ADHD code for?
The dopamine transporter
What are the names of the two genes which have been linked with ADHD?
- SLC6A3
- DRD4
If more dopamine transporters are available, what impact will there be on removal of dopamine from the synapse?
It will be removed from the synapse more effectively, meaning it has less chance to bind to receptors
What does DRD4 code for?
A specific type of dopamine receptor
If the receptor is less sensitive to dopamine, what would that mean for the postsynaptic neuron effect of dopamine binding to these receptors?
The usual effect of dopamine on the postsynaptic neuron would be subdued
What does the SLC6CA3 protein create?
A transporter which is more efficient at removing dopamine from the synapse, which reduces the amount available to bind to receptors
What does the DRD4 protein create?
Receptors with reduced sensitivity to dopamine
What is one of the biggest indicators that ADHD may have a dopaminergic basis?
The fact that medication used to treat it primarily targets this neurotransmitter
What is meant by the term descriptive statistics?
Data that describe or summarise features of a data set, such as the mean and standard deviation
What is meant by the term standard deviation?
The spread of data around the mean value
What is meant by the term inferential statistics?
Results of data or statistical analysis that allow inferences/predictions to be made from sets of data
What is a P value?
The probability that the difference between two data sets has arisen by chance alone
If a P value is close to zero, what does that mean?
It is less likely that the difference between two sets of data has arisen by chance (ie it is more likely that there is a genuine difference between the two groups)
To determine whether there is a statistically significant difference between two data sets, P values are compared with a cut-off value known as what?
The a value (alpha value)
What is an a (alpha) value?
The level of the P value is taken to denote statistical significance
What a value is usually used with regards to P values?
0.05
What is meant by the term parent training?
A type of training that aims to provide parents or carers with techniques for managing the behaviour of children
What ages of children is the Incredible Years parent programme suitable for?
From birth to 12 years
What are the key aims of the Incredible Years programme?
To support parents in developing child-centered behaviours such as play, following the child’s lead, and to ensure that parents reinforce positive behaviours in their children
What is meant by the term between-participants design?
An experimental design in which different groups of participants are used for each condition
What is meant by the term within-participants design?
An experimental design in which the same group of participants is used in both experimental and control conditions
What is meant by the term experimental condition?
The condition in which the suspected causal variable is present
What is meant by the term control condition?
The condition from which the suspected causal variable is absent
What is meant by the term order effects?
An effect on an experimental outcome measure that arises from the order in which participants are tested
What four factors are thought to compromise conditions including ADHD?
- Emotional or affective reactions
- Psychological symptoms
- Thoughts or cognitions
- Behaviours
In ADHD management, what does CBT focus on?
- Establishing structures and routines
- Establishing clear rules and expectations for key settings (eg work/school/home)
- Social skills with peers
- Problem solving
- Active listening skills
- Dealing with and expressing feelings
What is meant by the term psychostimulant drugs?
A class of drugs that typically increase activity of the central nervous system
When were psychostimulant drugs first discovered?
The 1930s
Which neurotransmitters fall into the category of monoamines?
- Dopamine
- Noradrenaline
- Serotonin
What is the role of the neurotransmitter transporter?
The transporter is normally responsible for removing neurotransmitter from the synapse
How does methylphenidate work?
By blocking the transporter (reuptake channel)
What effects does dopamine have at the synapse?
- Blocking transporters (uptake channels)
- Displacing dopamine from vesicles in the presynaptic neuron, which can then be transported into the synapse
What percentage of people discontinue treatment with long-acting ADHD drugs?
19%
What percentage of people discontinue treatment with short-acting ADHD drugs?
38%
What is the only non-stimulant drug treatment for ADHD currently available?
Atomoxetine
What role does the superior calliculus have in the brain?
It is part of the circuitry involved in selective attention and processing sensory information
What is synaptophysin?
A protein which aids release of neurotransmitter by interacting with synaptic vesicles
Where in the brain is the superior calliculus found?
The midbrain
Aside from blocking reuptake channels, what other effect does amphetamine have at the synapse?
It can displace dopamine from the vesicles within the presynaptic neuron, which can then be transported into the synapse
Methylphenidate and amphetamine both have what kind of effect on dopaminergic activity within the brain?
They increase it
