Week 1
Chapter 1 Child neuropsychology
Theory of recovery of function:
- Child’s brain is less differentiated than mature adult ⇒ transferring functions
- Critical period: the time window during which external influences have a significant effect
- Brain insult have different consequences at different times throughout development
- Brain damage during critical stage ⇒ cognitive skill is irreversibly impaired
Non-verbal learning disability (NVLD; Rourke’s model):
- NVLD accounts for a consistent pattern of neurobehavioral deficits in children with a history of
early, generalized cerebral dysfunction, occurs during perinatal period or infancy
- Hallmark characteristics of NVLD:
- Bilateral tactile-perceptual deficits
- More on left side of body
- Impaired visual recognition and discrimination and visuospatial organisational
deficiencies
- Bilateral psychomotor coordination problems
- More on left side of body
- Difficulties managing novel information
- NVLD intact skills:
- Primarily within auditory/ verbal domain
- Simple motor skills
- Auditory perception
- Rote learning
- Selective and sustained attention for auditory-verbal information
- Basic expressive and receptive language
- Word reading and spelling
- Timing of insult is important
- Normal development of white matter is essential for intact child development
- NVLD occurs when there is disruption to white matter development during critical stages of early
childhood
- Early brain insult doesn’t always lead to symptoms consistent with NVLD
Developmental stage at insult and cognitive outcome (Dennis’ heuristic theory):
- Focus on primarily on age/ developmental stage at time of insult and progression in cognitive
skills with time since insult
- Impact of brain damage on language development
- Skill development has different levels:
- Emerging: ability is in early stages of acquisition, but not yet functional
- Developing: a capacity is partially acquired but not fully functional
- Established: abilities are fully matured
- Theory integrates developmental skill levels with three crucial age-related variables:
- Age at time of lesion
- Determines nature of the cognitive dysfunction
- Early lesions disrupt onset and rate of language development; later lesions
associated with specific symptom pattern like high-level language dysfunction
, - Age at testing
- Important since healthy children vary in their abilities
- Early brain insults appear to cause relatively few problems early post-injury ⇒
ongoing development children may “grow into” deficits ⇒ fail to acquire
age-expected skills
- Time since insult
- Differing performance patterns identified at different stages of recovery, with
increases in some cognitive skills, but failure to develop others
- Model does not propose specific neurological mechanism, but implies that full impact of childhood
brain injury is not clear until brain maturation
Current multi-dimensional theoretical approaches:
Cognitive reserve model:
- Brain reserve capacity (BRC)
- Measured by insult severity, brain volume, structural connectivity, neurological sequelae
(e.g., epilepsy)
- When BRC is depleted below threshold levels ⇒ functional deficits emerge ⇒ physical,
cognitive, socio-emotional symptoms
- Cognitive reserve capacity (CRC)
- Intrinsic (pre-injury cognition and behavior and post-injury cognition) and extrinsic
(socio-economic status and family functioning) factors can influence functional outcomes
- Age and time variables are important for outcome
- Age = age at the time of insult, time elapsed since insult, child’s age at evaluation
- Lesion location and functional network involvement are important for functional outcome
- Greater the time elapsed since injury, the less effect of brain insult characteristics and the greater
the effect of environmental variables on cognitive functioning
,Recovery continuum model:
- Neither early plasticity nor early vulnerability theories in isolation are sufficient to explain the
outcomes following early brain insult ⇒ continuum approach ⇒ number of potential risk and
resilience factors interact to determine long-term outcome
- Model incorporates factors including:
- Nature (global, diffuse) and severity (mild/ severe, presence of complications) of insult,
developmental stage of child (infant child, adolescent), timing of assessment, pre-injury
child characteristics, environmental context (distal and proximal factors), access to
interventions and social support
- Impact of these factors may not be linear ⇒ larger lesions do not always result in poorer
outcomes; early injury is not always more toxic than later injury
- Factors interact
Dimensions of child neuropsychology: a biopsychosocial model
Bio dimension:
- Prenatal period: development is largely concerned with structural formation ⇒ establishing the
basic “hard-ware” of the brain
- Interruptions to brain development during this period results in structural abnormalities
(dysplasia, neural tube defects, agenesis of corpus callosum)
- Postnatal development: directed towards elaboration of the brain, establishing the connectivity
vital for the system to function effectively, process continues into early adolescence
- Process includes: dendritisation, synaptogenesis, myelination
- Development occurs in a hierarchical manner ⇒ anterior regions the last to reach
maturity
- Different things impact this process ⇒ brain injury/ insult, infection, environmental factors
(malnutrition), trauma, environmental toxins
- Early disruption to CNS may have irreversible consequences
- Nature and severity of cerebral insult are of primary importance, more severe and
widespread disruption leading to poorest outcomes
, - Childhood brain disorders are more commonly diffuse, impacting on the brain as a whole
(traumatic brain injury, cerebral infection, metabolic disorder); focal disorders (tumor, stroke) are
rare
- Specific impairments such as aphasias or modality-specific memory disorders are less
common
- Generalized disturbances of information processing (Attention, memory, psychomotor
skills), executive functions and social cognition are more observed
- Acute recovery appears to be similar irrespective of age
- Long-term recovery patterns differ ⇒ in favor of mature brain
- Prognosis more difficult to predict in childhood injury
- Plasticity theorists argue that damage to immature brain yields less disability than equivalent
insults in adults, however, longitudinal research indicates that such interpretations are too
optimistic ⇒ children will grow into their difficulties as demands increase through late childhood
- Transfer of function ⇒ debate
- Some evidence suggest that prenatal brain injury may not result in functional transfer, but
skills may be maintained effectively by damaged tissue ⇒ developmental delays
- Even if transfer takes place ⇒ could result in “crowding” of skills and generalized
depression of function
- Recovery following early brain insult is not static, but likely reflects ongoing disruption to
maturation of functional neural networks and have major negative impact on long-term outcome
Environment: social dimension
- Adaptive and positive interactions promote healthy, social development
- Problems (family trauma) ⇒ disruption in both the child and the environment
- SES, parent education and income,abuse, neglect, illness all influence development
Environment, neglect, trauma, abuse:
- Consequences of child neglect and abuse ⇒ reduced intellectual ability, attention, working
memory, self-regulatory deficits, lower levels of academic achievement and self-confidence,
mental health problems
- Evidence for changes in structure and function in developing brain
- Reduced brain volume (impacting gray and white matter)
- Deficits in structural connectivity
- Atypical brain activation
- Specific brain regions more susceptible to impact of neglect and abuse:
- Fronto-limbic networks, medial prefrontal cortex, orbital prefrontal cortex, hippocampus,
amygdala, corpus calosum
Environment, chronic illness, brain insult:
- A combination of environmental factors (low SES, presence of multiple family stresses, previous
psychological disturbance, low levels of maternal education) ⇒ predictive of poorer long-term
outcome in early-acquired brain insult
- Better outcomes are found where there is family cohesion and supportive social networks
- Above mentioned factors are consistent with the “double-hazard hypothesis” ⇒ brain insults may
have greater consequences in children from socially disadvantaged backgrounds
- Dysfunctional family ⇒ post-insult ⇒ poorer mental health and social problems in child
- Modifiable risk factor ⇒ improving parent and family function may have follow-on benefits for
child outcome
- Interventions focus on parenting and parent mental health
