Chapter 24 - Neurodevelopmental disorders Flashcards

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1
Q

What’s the broad definition of neurodevelopmental disorders?

A
  • Multifaceted conditions generally defined by significantly lower-than-average performance in a school subject
  • Origin in abnormal brain development
  • Encompasses disorders of attention, social behaviour, general cognition, learning, communication, motor skills
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2
Q

What are the general stages of brain development?

A

1) Cell birth (neurogenesis; gliogenesis)
2) Neural migration
3) Cell differentiation
4) Neural maturation (dendrite and axon growth)
5) Synaptogenesis
6) Cell death and synaptic pruning
7) Myelogenesis

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3
Q

Which brain development stages occur prenatally and which continue well into adulthood?

A
  • Cell birth - cell differentiation: Prenatally
  • Neural maturation - Myelogenesis: Continues well into adulthood
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4
Q

What important development occurs during weeks 4-6?

A
  • The neural tube is forming, very sensitive to insults (ex. drinking)
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5
Q

Why are gestational weeks 6-8 weeks so important for neural development?

A
  • Neurogenesis is in full force and new neurons are developing, and neural migration is about begin
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6
Q

How does dendritic growth differ from axonal extension?

A
  • Dendritic growth - helps provide surface area for synapses with other cells; occurs very slowly (arborization)
  • Axonal extension - to appropriate targets to initiate synapse formation; occurs very quickly (1000X faster)
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7
Q

T/F: Most intellectual disability cases are mild.

A
  • TRUE
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8
Q

Which sex is more diagnosed with intellectual disabilities? What’s a major risk factor?

A
  • Males are more commonly diagnosed
  • Poverty is a risk factor
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9
Q

What’s Cerebral Palsy (CP)?

A
  • Group of motor function disorders caused by brain damage or abnormalities either before, during, or after birth
  • Diverse causes can include blood clots, infections, and a wide range of traumatic brain injuries
  • Considered an intellectual disability
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10
Q

What are some of the major symptoms of CP?

A
  • Can be mild impairments in a single limb to severe impairments which can affect the entire body
  • May be accompanied by other impairments (cognitive, emotional, epilepsy etc.)
  • 35-60% of cases are associated with moderate to profound intellectual impairment
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11
Q

Is there a difference between incidence of CP in male and females?

A
  • No
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12
Q

What’s considered a risk factor for CP?

A
  • Premature births can increase incidence by 100-fold
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13
Q

What’s spastic CP?

A
  • Makes up around 50% of cases
  • Characterized by hypertonia (excessive muscle tone), worse when limbs are moved quickly
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14
Q

What’s athetoid CP?

A
  • Makes up around 25% of cases
  • Characterized by continuous ongoing movement (uncontrolled)
  • Often caused by severe oxygen deprivation at birth, basal ganglia and thalamus are affected
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15
Q

What’s rigid CP?

A
  • Makes up around 10% of cases
  • More continuous, uniform hypertonia, affects whole body
  • More severe than spastic
  • Brain regions affected: basal ganglia, brain stem, and spinal cord
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16
Q

What’s ataxic CP?

A
  • Affects around 10% of cases
  • Caused by cerebellum damage, may need an aid to walk on their own
  • Balance and coordination and voluntary movement most affected
  • The least severe form of CP
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17
Q

What’s hypoxia?

A
  • Diminished oxygen flow during
  • May lead to an intellectual disability
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18
Q

What’s hydrocephalus?

A
  • Abnormal buildup of CSF in the ventricles
  • CSF bathes entire brain (cushions, adds buoyancy, provides ions etc.)
  • CSF flow is blocked
  • Atrophy of surrounding brain tissue leads to ventricle enlargement
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19
Q

When does infant hydrocephalus develop?

A
  • Usually develops during first 3 months
  • Affects around 2/1000 babies
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20
Q

Where is CSF produced and where does it move to?

A
  • Produced in the choroid plexus
  • Moves downward to the fourth ventricle
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21
Q

Where may CSF get blocked in hydrocephalus?

A
  • The cerebral aqueduct
  • The fourth ventricle
  • The foramen of Magendie
  • Foramen of Luschka
  • Foramen of Monro
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22
Q

How does CSF circulate throughout the brain?

A
  • The subarachnoid space (found between the arachnoid membrane and the pia mater)
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23
Q

What’s the most common cause of hydrocephalus?

A
  • Most are the result of inflammation of trauma
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24
Q

What are the treatments for hydrocephalus?

A

1) Endoscopic third ventriculostomy (drilling a hole in the third ventricle, allows for fluid to leak out)
2) Shunt (permanent, inserted into lateral ventricle, most common solution)

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25
Q

What’s Fragile-X Syndrome?

A
  • The most common inherited cause of an intellectual disability and autism spectrum disorder
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26
Q

Which sex has more learning disabilities with Fragile-X syndrome?

A
  • Most boys have learning disabilities, compared to only 1/3 of affected girls
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27
Q

What symptoms are found in Fragile-X syndrome?

A
  • Facial abnormalities and mental disabilities
  • Attention deficits, hyperactivity, anxiety, unstable mood and behaviour
28
Q

What causes Fragile-X syndrome?

A
  • Caused by mutations in the FMR1 (fragile X Messenger ribonucleoprotein 1) gene on the X chromosome
  • Mutation is a trinucleotide repeat (CGG) expansion
  • Leads to loss of the FMRP (Fragile-X mental retardation protein)
  • FMRP participates in synapse formation (GABA and glutamate receptors) and functioning
29
Q

What are some structural differences in Fragile-X syndrome?

A
  • Poorly formed and more numerous dendritic spines
  • MRI scans show cortical thinning, small caudate nucleus, and an increase in ventricular size
30
Q

What’s Fetal Alcohol Spectrum Disorder (FASD)?

A
  • Caused by abuse of alcohol by mothers/fathers preconception, or mothers during pregnancy
  • Physical malformation and intellectual impairment
  • Varying degrees of learning disability, relatively low intelligence scores, hyperactivity, social problems
31
Q

What may be some theories for the effects of alcohol toxicity on the developing brain?

A
  • Cell death
  • Cell signalling defects
  • Gene expression changes, including epigenetics
  • Vitamin deficiencies
32
Q

What causes Down Syndrome?

A
  • Congenital condition caused by an extra copy of chromosome 21
  • Failure of chromosome 21 to separate during meiosis
  • 88% of trisomy 21 cases result from nondisjunction during oogenesis
33
Q

T/F: Down syndrome is the least common chromosome abnormality in humans.

A
  • FALSE, it’s the most common
34
Q

What are some of the health risks of Down Syndrome?

A
  • 50% may have heart defects which require surgery in early infancy
  • Increase risk of developing autoimmune disorders
  • Higher risk of sleep apnea
  • More prone to obesity
  • Increase risk of developing dementia and Alzheimer disease
35
Q

What’s language disorder?

A
  • Persistent difficulties in learning and using spoken, written, or sign language
  • Understanding or using language, or both
  • Impairment usually extends to vocabulary, sentence structure, and discourse
36
Q

What are the general symptoms of a language disorder?

A
  • Short and simple sentences
  • Grammatical errors in speech
  • Small vocabulary
  • Word-finding difficulties
  • Persists into adulthood
37
Q

What’s the Wernicke-Geschwind model?

A
  • Classical anterior and posterior speech zones are connected by the arcuate fasciculus
38
Q

What may be the cause of a language disorder?

A
  • There’s a strong genetic component
  • The anterior frontal cortex pathways representing language syntax and meaning it may not fully mature
39
Q

What’s speech sound disorder?

A
  • Impaired pronunciation and articulation
  • May be due to difficulty with phonological knowledge or ability to coordinate movements necessary for speech
40
Q

What are some speech sound disorder symptoms?

A
  • Dropping, adding, distorting, or swapping word sounds
  • Saying only 1 syllable in a word
  • Simplifying a word by repeating 2 syllables
  • Leaving out a consonant sound
  • Changing certain consonant sounds
  • Running out of air while speaking
  • Hoarse, raspy, or nasally sounding voice
41
Q

What’s childhood-onset fluency disorder?

A
  • AKA stuttering
  • Fluency and rhythm of speech are interrupted
  • 4X more likely in males
  • Onset usually during 306 years, but is usually outgrown
41
Q

What’s the cause of speech sound disorder?

A
  • The cause is not well understood (often idiopathic)
  • There is a genetic component
42
Q

Developmental vs. Acquired childhood-onset fluency disorder?

A
  • Developmental - Number of structures in frontal and temporal cortices (both hemispheres)
  • Acquired - May occur after trauma/emotional and/or physical stress, or following neurological injury
43
Q

How does childhood-onset fluency disorder impact brain connectivity?

A
  • May be due to decreased white matter ‘integrity’ along left dorsal language tract (make it hard for articulation)
  • ‘Integrity’ - axon density, myelination, axonal diameter
44
Q

What’s social communication disorder?

A
  • Impaired verbal and nonverbal communication for social purposes
  • Difficulties with indirect use of language (i.e., implied sentences, metaphors, humour, aphorisms
  • Presence of ASD excludes an SCD diagnosis
45
Q

What are some major symptoms of ASD?

A
  • Impaired social interaction, narrow range of interests, abnormal language/communication skills, fixed and repetitive movements, and in some cases intellectual impairment
46
Q

What is Asperger syndrome called now?

A
  • Often referred to as high-functioning autism
  • They have good verbal communication, but difficulty with social communication
  • Narrow repetitive play, poor peer relations, need for routine/sameness
  • May excel in some aspect of behaviour
  • Can develop exceptional memory abilities
47
Q

T/F: ASD is 4X more common in boys

A
  • TRUE
48
Q

What is characteristic of the brain in those with ASD?

A
  • Brain characterized by accelerated rates of neuronal maturation
  • Excessive brain volume in the amygdala, temporal and frontal lobes
49
Q

What are some other anatomical correlates of ASD?

A
  • Von Economo neurons may fail to develop normally
  • These are large bipolar neurons found in areas of cortex associated with social cognition
  • Develop late, around age 4
  • May also be brainstem changes, such as a reduced size in posterior pons
50
Q

Where are VENs found in the brain?

A
  • DLPFC
  • Frontal insular cortex
  • Anterior cingulate cortex
51
Q

ACC vs. Insula in social cognition?

A
  • ACC - empathy, impulse-control, emotion, decision-making
  • Insula - empathy, trust, guilt, humor, etc.
52
Q

Why are VENs? important?

A
  • May allow for rapid adjustment to changing social contexts
  • They contribute to out theory of mind
53
Q

How may the cerebellum differ in those with ASD?

A
  • Decreased Purkinje cell counts in the cerebellar cortex and cerebellar volume
  • Cerebellar atrophy
  • Patients with cerebellar agenesis may have symtpoms of ASD
54
Q

What are the three core symptoms of ADHD?

A

1) Inattention
2) Hyperactivity
3) Impulsivity
*All must be present before age 12
*impulsivity must be present in any diagnosis

55
Q

Which ADHD symptoms are more common in which sexes?

A
  • Inattention is more common in females
  • Hyperactivity and impulsivity are more common in males
56
Q

T/F: Boys are 3X more likely than girls to have ADHD.

A
  • FALSE, it’s 2X more likely
57
Q

What are the structural differences in those with ADHD?

A
  • Widespread structural (gray matter) and connection (white matter) irregularities
  • Affects specifically the frontal-striatal, frontal-parietal networks
  • Also reductions in orbitofrontal gray matter and basal ganglia gray matter
58
Q

What’s the main cause of ADHD?

A
  • Largely genetic, may also be environmental risk factors (e.g., prenatal smoking, neonatal anoxia, childhood lead exposure)
59
Q

What stimulants are often prescribed for those with ADHD?

A
  • Methylphenidate (Ritalin)
  • Amphetamine (Adderall)
    *Both work by increasing levels of DA/NE.
60
Q

What can perinatal brain injury result in?

A
  • Can lead to neonatal encephalopathy
  • Most commonly due to hypoxia-ischaemia
61
Q

Which brain region may exposure to ACEs effect?

A
  • May compromise frontal lobe development
62
Q

What were some of the outcomes of the case of the Romanian orphans?

A
  • Astounding recovery if adopted before 2 years of age
  • By 12 years of age: average brain size was up to 20% smaller, and widespread reduction in cortical white and grey matter
  • Unresolved cognitive and behavioural problems
  • PFC, HPC, and amygdala likely affected
63
Q

What has prenatal stress been associated with in terms of brain function?

A
  • Increased size of amygdala
  • Decreased size of HPC
  • Later development of depression and anxiety disorders
64
Q

What did Donald Hebb do?

A
  • Provided enriched environments for rats and discovered they performed better on the Hebbs-William maze than lab-reared controls
  • He reared a group of rats in his kitchen
65
Q

What were some differences found in rats that were reared in rat condos?

A
  • Larger, more complex cortices, richer in synapses
66
Q

What’s Tooley’s Integrative Theory?

A
  • Stress accelerates brain development
  • High SES children = slower segregation of connectivity into adult networks
  • Positive and rare experiences lead to slower maturation and enhanced plasticity, while repetitive and negative experiences lead to faster maturation and reduced plasticity