Week 12: Neurodevelopmental disorders Flashcards
Malformation of the brain tissue during neurodevelopment is….
Often incompatible with life and will end in miscarriage or still births
However some can and do survive with deficits
What is hydrocephaly?
Occurs when there is excess CSF in the ventricles of the brain, increasing intracranial pressure
When does hydrocephaly occur?
Can occur prenatally due to congenital issues such as spina bifida
or
Peri or postnatally most likely due to an intraventricular haemorrhage among premature infants but may also be due to infections, cysts and brain injury
How do they relieve intracranial pressure in hydrocephaly?
Can use a shunt to drain the CSF from the ventricles
What are the 2 genetic and chromosomal disorders focussed on in this unit?
Turners’ syndrome
Williams syndrome
What causes turners’ syndrome?
Partial or total deletion of the X chromosome - meaning females are affected
People with turners’ syndrome do not develop….
Secondary sex characteristics
E.g. the development of ovaries is specifically affected
What is turners’ syndrome co-morbid with?
Learning disabilities and behavioural symptoms (ADHD or hyperactivity)
Explain intelligence in turners’ syndrome
Have low to average IQ but their verbal IQ is often way higher than their performance IQ
What treatments are used for turners’ syndrome?
Growth hormones
Sex hormone therapy
What causes williams syndrome?
Deletion of part of chromosome 7
Williams syndrome is….
rare
Are there any gender differences in Williams syndrome?
No it is equal in males and females
Those with williams syndrome are very….
Sociable, empathetic and talkative
What are the strengths of those with williams syndrome? but what are the slight downsides to these?
They have remarkable language skills despite their low IQ - this may mask their underlying disability
They have perfect pitch and sense of rhythm (musical ability) - however this makes them sensitive to sounds in their environment
What are some of the things those with williams syndrome struggle with?
Attention
Spatial abilities
Drawing objects
Problem solving
What distinct physical features do those with williams syndrome have?
An upturned nose and a broad mouth
What can be co-morbid with williams syndrome
CVD Gastrointestinal problems Kidney issues Bladder problems Joint problems (that affect motor control & delays motor development)
What changes occur in the brain for williams syndrome?
Cortical thinning (in parietal/occipital boundary and in the orbitofrontal cortex - explaining impairments in spatial cognition and hyper sociability)
Which area is spared in williams syndrome brains?
Superior temporal gyrus
auditory cortex - relates to musical ability
What are acquired (or preventable) disorders?
Occur when there is an injury to the brain either pre or postnatally
Typically due to radiation, toxins, malnutrition, tumours, brain injury
What is the most common acquired but preventable condition in children?
Fetal alcohol syndrome (an umbrella term for many conditions)
What causes fetal alcohol syndrome?
Occurs due to prenatal exposure to alcohol
Symptoms of fetal alcohol syndrome relate to the…
Dose and frequency of prenatal alcohol use
Alcohol consumption during pregnancy is more damaging when?
Throughout the first trimester of if used consistently throughout the whole pregnancy
What are the symptoms of fetal alcohol syndrome?
Increased risk of low birth rate and reduced growth Poor muscle tone and coordination Seizures or tremors (neurological) Below average IQ + learning difficulties Inattention Hyperactivity Poor behavioural regulation
What treatments are there for fetal alcohol syndrome?
Prevention is better than cure
There is some opportunity to identify mothers that need help to reduce consumption
Child:
- Learning support
- Behavioural management therapy
- Speech and learning therapy
- Can use medication for ADHD like symptoms
- Social skills training
What is autism spectrum disorder (ASD)?
a complex developmental condition that involves persistent challenges in social interaction, speech and nonverbal communication, and restricted/repetitive behaviors
When does ASD become apparent?
Between 1 and 3 years
Are there any gender differences in ASD?
75% are male
What is ASD generally co-morbid with?
Intellectual impairments and learning disabilities
How does ASD present in infants?
Poor eye contact Not responding to their name Lack of showing and sharing No gesturing by 12 months Loss of language or social skills
How does ASD present in preschool children?
Limited pretend play
Odd or intensely focussed interests
Rigidity or inflexibility
How does ASD present in school-age children?
Concrete or literal thinking
Trouble understanding emotions
Lack conversational skills or appropriate social approach
What are the causes of ASD?
Can be genetic or environmental
- also gene-environment interaction
Explain genetics and ASD
50% inheritability rates - greater risk among siblings or first-degree relatives
Genes that regulate brain development, neurotransmitter function and synapses have been identified
The environmental causes of ASD?
Perinatal birth complications
parental age (advanced age of parents)
Exposure to infections, pollution, nutritional factors
Maternal infection or immune activation during pregnancy
ASD is characterised by increased brain volume. Where?
In frontal and temporal lobes
White and gray matter in ASD
There is excess white matter and disrupted connectivity between areas
there is reduced cortical thickness in the temporal cortex and increased in frontal cortex
What functional findings are there regarding autism brains
There is a mixed findings of increased and decreased glucose metabolism and blood flow compare to controls often in the limbic frontal and temporal areas
What social factors are largely affected in autism
Impairments in theory of mind and emotion perception and processing
What cognitive functions are moderately affected in autism
Processing speed verbal learning and memory
What treatment is there for autism
You can use intensive learning experience and behavioural interventions in early childhood target communication and social behaviours
There are no recommended medications for the core symptoms but antipsychotics and prescription stimulants can sometimes be prescribed for other behavioural symptoms
What is attention deficit hyperactivity disorder
Persistent patterns of inattentiveness and impulsivity and hyperactivity
When is the typical onset of ADHD
Typically occurs before 12 years of age
How many children have ADHD
5 to 7%
How many adults have ADHD
2.5%
Are there any gender differences in ADHD
It is two times more likely in males
What are the three subtypes of ADHD
A combined subtypes with both of the core symptoms
A predominantly inattentive presentation
A predominantly hyperactive impulsive presentation
What are are some of the inattentiveness symptoms of ADHD
Low attention to detail, can’t sustain attention, doesn’t listen when spoken to, can’t follow instructions a complete tasks, loss of items necessary for activities, easily distracted
What are some of the hyperactivity and impulsivity aspects of ADHD
Often fidgets with hands or feet
Leaves their seat in situations when they’re not supposed to
Often runs or climbs in situations where it is inappropriate
Can’t be engaged in activities quietly
Often talks excessively
Has difficulty waiting their turn
Interrupts often
What are some common psychiatric and medical comorbidities in ADHD
Tourettes Mood disorders Learning disabilities Diabetes Hypertension Epilepsy
What are some challenges or risks for those with ADHD
Academic performance School-related problems Risk-taking Social relationships Antisocial behaviour Drug abuse
What is the inheritability rate of ADHD
70 to 80%
What genes are involved in ADHD
There is a focus on the dopaminergic system associated with reduced dopamine and dopamine agonists are affective in treatment
other serotonergic genes are under investigation
What are some environmental factors towards the cause of ADHD
Prenatal events such as low birth rate and complications
Substance exposures, heavy metal and chemical exposure
Nutritional factors such as vitamin D and omega three
Lifestyle and Psychosocial factors such as stress poverty and trauma
What are the functional findings of ADHD brains
The frontostriatal structures and pathways are different such as reduced bloodflow in frontal lobes and basal ganglia during tasks that require cognitive control
These areas have rich dopaminergic projections and the medication to treat ADHD modulates the basal ganglia and frontal lobe activity working to increase the activity in these areas
Explain EEG patterns in ADHD compare to normal controls
There is greater theta and beta ratios which is a marker of cognitive control.
When engaging in control there is a reduction in this ratio showing that ADHD children do not have the same level of cognitive control
What cognitive processes are different in ADHD
Reduction in both focused and sustained attention
Verbal and working memory differences
Executive functioning differences such as planning, reward processing, risky or impulsive decision making, inhibitory control and attentional control
What is the dopamine hypothesis of ADHD
Thought to be associated with reduced extracellular dopamine
Treatment with dopamine agonists inhibits the re-uptake of dopamine so there is more dopamine in the extracellular space
What is the maturational delay hypothesis of ADHD
Delayed cortical thickness meaning delayed development of high cognitive functions and symptoms tend to improve or normalise with age as many children do not have severe symptoms of ADHD in adult hood
This is thought to be due to the late development of frontal lobes
What is the network dysfunction model of ADHD
Suggests a hyperactive or reduced activity in the pre-frontal cortex that is required for organisation and planning accounting for in attention and disorganisation
However it does not account for impulsivity and hyperactivity
What are the three separate attentional network models
Alerting model
Orienting model
Executive control network
What is the alerting network within the attentional network model
It governs our general level of arousal and our vigilance
It is maintained by nopinephrine that is synthesised in the locus calculus of the pons projecting broadly throughout many areas of the brain
What is the orienting network of the attention of network model
It is important to directing our attention to prioritise external information by selecting something to attend to
This can be automatic or voluntary it may catch our eye and we orientated towards it or we may wish to attend to it
The dorsal system is top-down and more voluntary
The ventral system is bottom up and re-orientating
What is the temporal parietal Junction and how is it involved in the ventral system of the orienting network
It acts as an interrupt feature so that if something appears in our environment that we need to attend to it will interrupt our current processing and re-orientate us to that novel stimulus in the environment
What is the executive control network of the attentional network model
It is involved in high-level regulation of the other systems including the orienting and alerting systems
it is important to prioritise information information for our current goals
Explain the ventral system hypos and hyper situations
If it’s hypo the deficits in detecting irregularities in the environment and this my underlying problems in modulating behaviour based on changes
If it’s hyper it may end up in some of the distractibility symptoms for example this circuit is a bracket to orient I will attention so increased activation he may increase this instead of focusing on what is really important
What is the reward model of ADHD
It can explain attention and impulsivity
The striatum, anterior cingulate cortex and orbitofrontal cortex central to reward processing
What is the mind at rest theory of ADHD
It’s the default mode network this is active when you’re at rest and deactivated when you’re focused on a task so that other networks are important for the task activated imaging research shows that ADHD children are slow to switch off this network and it corrects with methylphenidate
What are the pharmacological treatment of ADHD
Dopamine and norepinephrine agonists
They stop the reuptake and increases dopamine availability up regulating striatal to pathways
What are the nonpharmacological treatments of ADHD
The typically less affective in terms of ADHD symptoms but they are helpful for symptoms that are left over after the medication is taken affect
Things such as behavioural interventions
Oh there’s things like cognitive training neuro feedback dietary nutrition information and caffeine
What is dyslexia
Defined by specific reading disability is despite normal intelligence and exposure to adequate reading instructions
What aspect of reading to those with dyslexia struggle with
Have problems with decoding written text instead of oral language comprehension
How prevalent is dyslexia
7%
Are there any gender differences in dyslexia
It is more common in males
What are the common comorbidities of dyslexia
ADHD, language impairment and speech sound disorder
Are there any cultural differences in dyslexia
There are severe cases of dyslexia when language is consistent in grapheme phoneme mapping this is not the case in English
What is the genetic heritability rate of dyslexia
50%
What are the brain differences in dyslexia
There are various subtle visual auditory and motor deficits seen however because there are different types of dyslexia there are possibly multiple causes
likely to stem from a deficit of phonological processing so the representation and comprehension of speech sounds
What are the two aspects of the dual route model of word recognition
Lexical or the direct route
Phonetic or the indirect route
What is the lexical route of the dual route model of word recognition
The word is recognised as a whole unit and translated directly to meaning
used for reading with familiar and irregular words
this is what we use when we become efficient in reading in order to comprehend it
What is the phonetic or indirect route of dual route model of word recognition
Letters are translated into sounds
using grapheme phoneme conversion
so this is used for reading unfamiliar and nonwords non-words
What is the visual theory of dyslexia
Based on observation that people with dyslexia often make word reversal errors it was argued that this was a result of a failure in establishing hemispheric dominance
What is the phonological theory of dyslexia
Grapheme phoneme conversion route that seems to be the problem issues with reading words through this process of phonological decoding
What is the most largely excepted best explanation of dyslexia theories
The phonological theory
What is the orthographic learning theory of dyslexia
It emphasises the ability to establish those mappings between phonemes and graphemes rather than just a problem with the final logical representation of them themselves
What is the visual attention theory of dyslexia
Performance on visual tasks is often different in people with dyslexia compare to neuro typical
This performance can predict reading ability at a later point in time
What are the new mechanism differences in dyslexia
There is disrupted activation of the left hemispheric language network
The temporal region for phonological processing in grapheme and phoneme conversion
Occipital temporal for visual word form area and whole word recognition
What are the treatments for dyslexia
It is recommended the children identified early
They can undergo early intensive instructions to learn how to read phonics maybe resulting in the normalisation of the reading and language left hemispheric networks
