Week 12 - Neurodevelopmental Disorders Flashcards
What is a type of abnormality of anatomical development?
Hydrocephaly
What is hydrocephaly?
Abnormal build up of cerebrospinal fluid (CFS) in the ventricles of the brain
What are some genetic and chromosomal disorders?
Turner’s syndrome
Williams syndrome
What are acquired neurodevelopmental disorders?
Fetal alcohol syndrome
What is Turner’s syndrome?
Partial or total deletion of X chromosome affecting females
Do not develop secondary sex characteristics, short stature, other physical features
Comorbid with learning disabilities and behavioural symptoms
Low-average IQ
What are some treatments for Turner’s syndrome?
Growth and sex hormone therapy
What is Williams syndrome?
Distinct physical features
Sociable, empathetic, talkative
Remarkable language abilities for characteristically low IQs
What are some strengths of people with WIlliams syndrome?
Sociable, empathetic, talkative
Remarkable language abilities for characteristically low IQs
Other cognitive strengths include near-perfect pitch, a sense of rhythm and a remarkable ability to recognise faces
What problems are associated with Williams syndrome?
Severe attentional problems,
poor spatial abilities
Difficulty drawing objects
What are the brain changes associated with Williams syndrome?
General thinning of cortex
- Boundary of parietal and occipital lobes
- Orbitofrontal cortex
Spared in superior temporal gyrus (auditory cortex)
Why may people with Williams syndrome have a remarkable sense of pitch and rhythm?
No deficits in superior temporal gyrus (auditory cortex)
What is fetal alcohol syndrome?
characteristic physical features
microcephaly, low birth weight, reduced growth
Poor muscle tone and coordination
Below average IQ, inattention, hyperactivity, learning disabilities, poor behavioural regulation
What are some communication neurodevelopmental disorders?
Language disorder
Speech sound disorder
Childhood onset fluency disorder (stuttering)
Social (pragmatic) communication disorder
What are some motor neurodevelopmental disorders?
Developmental coordination disorder
Stereotypical movement disorder
Tic disorder
What are the core symptoms of autism spectrum disorder?
Reduced capacity for social interaction and communication
Restricted and repetitive patterns of behaviour, interests or other activities
What are the early signs of autism in infants?
poor eye contact
poor response to name
lack of showing and sharing
no gesturing by 12 months
loss of language or social skills
What are the early signs of autism in pre-school-aged children?
Limited pretend play
odd or intensely focused interests
rigidity
What are the early signs of autism in school-aged children?
Concrete literal thinking
trouble understanding emotions
lack conversational skills or appropriate social approach
What is the genetic basis of autism?
heritability 50%
many genes identified
gene-environment interaction
What are the environmental factors of autism?
Perinatal or birth complications
parental age
exposure to infection, pollution, pesticide, nutritional factors
What did Pinel describe as the neural mechanisms in autism?
Variability in underlying neural correlates
Post mortem and structural studies implicate cerebellum, amygdala, frontal and temporal cortex, white matter connectivity
What are the structural findings of autism?
Enlarged brain volume
Increased volume in frontal and temporal lobes
Reduced cortical thickness in the temporal cortex
Increased cortical thickness in the frontal cortex
Fewer/smaller neurons in cerebellum and frontal and temporal cortices
Smaller subcortical volume, greater volume in caudate nucleus
Excess white matter and disrupted connectivity between areas
What are the functional findings of autism?
Mixed findings of increased and decreased glucose metabolism and blood flow compared to control
often limbic, frontal and temporal areas
What are the treatments for autism?
Intensive learning experiences and behavioural interventions in early childhood
No recommended pharmacological treatment for core symptoms
antipsychotics and prescription stimulants sometimes prescribed for other symptoms
What are the core symptoms of ADHD?
Inattentiveness
Impulsivity and hyperactivity
What are the challenges/risks associated with ADHD?
academic performance
school-related problems
risk taking
social relationships
antisocial behaviour
drug abuse
What is the genetic basis of ADHD?
Heritability 70-80%
Multiple genes focussed on the dopaminergic system
Epigenetic effects
What environmental factors contribute to ADHD?
Prenatal events and substance exposures, Heavy metal and chemical exposures, nutritional factors
and lifestyle/psychosocial factors
what are the structural findings of ADHD?
Reduced brain volume
Smaller volume of subcortical structures (basal ganglia, amygdala, hippocampus) cerebellum, prefrontal cortex and corpus callosum
Peak cortical thickness is delayed 3 years
Disrupted cortical thinning and white matter connectivity between hemispheres
What are the functional findings of ADHD?
Fronto striatal structures and pathways
Mixed findings in relation to D2, D3 receptor availability and density of dopamine transporters
Gene variants related to the dopaminergic system may modulate fronto-striatal circuitry
What are the cognitive deficits related to ADHD?
Focused attention
Sustained attention
Verbal memory
Working memory
Executive function
What is the dopamine hypothesis of ADHD?
It is associated with reduced extracellular dopamine
Treatment with dopamine agonists inhibits the reuptake of dopamine
What is the maturational delay hypothesis?
Delayed development of higher cognitive functions (Inhibitory control, attention, temporal foresight)
Symptoms tend to improve with age
What does neuroimaging suggest about the naturational delay hypothesis of ADHD?
Reduced size of cortico-striatal regions and reduced functional activation
What do the network dysfunction models of ADHD suggest?
Hypoactive PFC - organisation and planning, value based decision making. accounts for inattention and disorganisation
What are the different types of network dysfunction models of ADHD?
Attention model
Reward model
‘mind at rest’
What did cortese et al (2012) suggest about the attention model of ADHD?
Fronto parietal system: goal directed executive control processes
Ventral attention system: orienting to salient external stimuli
Doral attention system: Select external stimuli based on goals, experience, memory
What did ortiz et al (2015) find about the Reward model of ADHD?
Hypoactivity in the striatum for reward anticipation
Hyperactivity dLPFC and OFC for reward receipt
What is the reward model of ADHD?
Related to the striatum, ACC, OFC central to reward processing
Delayed gratification, impulse control
Significance not assigned to longer term goals
What is the mind-at- rest model of ADHD?
Default mode network (DMN) - active when at rest, deactivated when task focussed
Mind wandering, day dreaming, contemplating, reflecting
What does imaging research show about the mind-at-rest model for children with ADHD?
ADHD children are slow to switch off DMN - corrects with methylphenidate
How can you switch off DMN in children?
Methylphenidate
What are some pharmacological treatments for ADHD?
Dopamine and norepinephrine agonists:
Dextroamphetamine, methylphenidate (ritalin) mixed with amphetamine (adderall)
Sometimes NE agonists (atomoxetine) antidepressants or anticonvulsants
What is the core symptom of dyslexia?
Specific reading disability
What is the genetic basis of dyslexia?
Strong genetic influence
Heritability 50%
What are the environmental factors associated with dyslexia?
Lower SES = 5-10 variance in reading
What are the causes of dyslexia?
Various subtle visual, auditory and motor/cerebellar deficits are commonly seen
Multiple types of developmental dyslexia - possibly multiple causes
Likely to stem from a deficit of phonological processing (representation/comprehension of speech sounds) rather than sensorimotor processing
What is included in the dual-route model of word recognition?
Lexical (orthographic/direct) route
Phonetic (phonological/indirect) route
What is the lexical route of the dual-route model of dyslexia?
Word recognised as a whole unit and translated directly to a meaning
Used for reading familiar and irregular words
What is the phonetic route in the dual-route model of dyslexia?
Letters translated into sounds (phonemes) using grapheme-phoneme conversion (GPC) rules and sounds are blended together
Used for reading unfamiliar and nonwords
What are the causal theories of dyslexia?
Visual theory
auditory processing theory
cerebellar theory
Magnocellular visual theory
Phonological theory
Orthographic learning
Visual attention theory
What are the neural mechanisms of dyslexia?
Disrupted activation of LH language network
- Temporoparietal regioln: phonological processing and grapheme phoneme conversion
- Occipito-temporal: visual word form areas, whole word recognition
- LH inferior frontal gyrus
How is dyslexia treated?
Early intensive explicit instruction
Phonics based reading instruction
