Inherited urea cycle disorders disrupt the body's ability to remove ammonia, which can damage the brain's white matter. White matter allows different brain regions to communicate, so damage interferes with cognitive functions. A neuropsychological evaluation assesses strengths and weaknesses by comparing test scores to peers, helping to understand behavior and guide treatment. Damage to white matter from urea cycle disorders may impair executive functions, processing speed, coordination and mood.
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Neuropsychological Implications Of Ucd
1. The Neuropsychology of Urea Cycle Disorders M. Cullen Gibbs, Ph.D. Pediatric Neuropsychologist Children’s National Medical Center
2. Neuropsychological Implications of UCD Inherited urea cycle disorders (UCD) represent one of the most common groups of inborn errors of metabolism; however, little information is available on the natural disease progression in persons with UCD. In UCD the failure of the urea cycle to rid the body of excess ammonia causes hyperammonemia episodes. These episodes result in toxic effects on the white matter of the central nervous system.
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4. The Importance of White Matter White matter is, in essence, the mechanism by which different regions of the brain communicate with each other. White matter fibers in the brain allow communication between the left and right cerebral hemispheres, within the cerebral hemispheres, and between the brain stem and the cerebral hemispheres Damage to the white matter interferes with the ability of different regions of the brain to communicate, resulting in cognitive impairment.
5. Why is the Impact of Disease Processes on Neuropsychological Functioning Difficult to Identify in Children? Opposing vectors of development and deterioration mask effects of disease The premorbid level of ability is a rate of development, not a level of performance.
6. Developmental status Chronological age Vector of normal development Vector of disease effect Hypothetical Effects of Disease and Normal Development on Growth Trajectory Courtesy of Dr. Elsa Shapiro; University of Minnesota Medial School. 0 2 4 6 8 10 3 4 5 6 7 8 9 10 Resultant of vectors of development and disease in affected child
7. Problems in the Assessing the Cognitive Impact of Disease Processes in Childhood Unknown premorbid intellectual level Difficult to identify cognitive changes in early stages of disease Impact may vary according to age of onset
8. Problems Assessing the Cognitive Impact of Disease Processes in Childhood Because certain mental functions are not yet developed at the outset of the disease and cannot be measured, the extent of the impact may not be detected until those functions are developmentally ready to emerge. Presence of confounding factors, both biological and environmental.
9. What is Neuropsychology? The study of learning and behavior in relationship to a child’s developing brain. A framework that draws from cognitive sciences, neurology, neuroanatomy, and clinical, social, developmental, biological psychology.
10. What is a Neuropsychological Evaluation? Examination of external behavior to make inferences about internal brain function and structure. Formal testing of abilities such as memory and language skills assesses brain functioning. By comparing a child’s test scores to children of a similar age, it is possible to create a profile of the child’s strengths and weaknesses.
11. What is the Purpose of a Neuropsychological Evaluation? To understand, explain and predict behavior Develop a profile of an individual's cognitive strengths and weaknesses Describe presence and degree of cognitive impairments and explain mechanisms responsible for their perpetuation
12. What is the Purpose of a Neuropsychological Evaluation? Measure presence and degree of behavioral difficulties resulting from neurological bases Establish baseline of functioning for systematic comparisons across time Measure the cognitive or behavioral impact of rehabilitation, pharmacological, surgical or therapeutic interventions
13. What is the Purpose of a Neuropsychological Evaluation? Help formulate appropriate treatment plans Guide remedial educational or vocational rehabilitation programs Predict individual's ability to achieve success in particular settings Needs for settings to accommodate to the individual versus individuals' ability to adapt to the setting
16. Lateral Axis Left Hemisphere Systems Preferentially involved with: Building blocks of language Parts of complex materials Temporal processing Processing unimodal, codable information Executive of discrete motor Right Hemisphere Systems Preferentially involved with: Spatial information Relationship between parts Configuration of complex Processing multi-modal novel information Emotional tone in speech <-->
17. Domains of Neuropsychological Functioning General cognitive functioning Attention Executive-regulatory function Language Visual/Nonverbal processing Memory& Learning Sensory and Motor Academics Social & emotional
18. What are the Potential Neuropsychological Implications of Damage to the White Matter? Impaired executive functions Slowed speed of processing Impaired spatial processing Impaired coordination Dysarthric speech Depressed mood Cummings, 1990
19. What are the Executive Functions? An “umbrella” term, encompassing… those interrelated skills necessary for purposeful, goal-directed activity” ( Anderson, 1998) “ Capacities that enable a person to engage successfully in independent, purposeful, self-serving behaviors” (Lezak, 1993)
20. Role of the Executive Conductor of the orchestra" “ CEO of the corporation” “ General of the army” “ Domain general processes”
22. Functions of the “Conductor” 1. Initiate goal-oriented action 2. Working Memory 3. Plan & Organize 4. Self-monitor & evaluate 5. Inhibit 6. Flexibility 7. Emotional regulation 8. Self-awareness
23. Functional Domains of The Executive Inhibit - stop an action or not react to impulse Shift - move from one task or situation to another Emotional Control - regulate emotional response Initiate - begin task, activity, attention Working Memory - hold information actively in mind Plan - anticipate future events and develop steps Organize - establish, maintain order Self-monitor - attend to behavior/output; revise
24. Functions of the “Orchestra” 1. Perception 2. Conceptual thinking 3. Language processes 3. Visual-spatial processes 4. Memory 5. Sensory inputs 6. Motor outputs 7. Emotion 8. Knowledge & skills social non-social
25. Functions of the “Conductor” 1. Initiate goal-oriented action 2. Working Memory 3. Plan & Organize 4. Self-monitor & evaluate 5. Inhibit 6. Flexibility 7. Emotional regulation 8. Self-awareness Functions of the “Orchestra” 1. Perception 2. Conceptual thinking 3. Language processes 3. Visual-spatial processes 4. Memory 5. Sensory inputs 6. Motor outputs 7. Emotion 8. Knowledge & skills social non-social
26. Critical features of Executive Control Functions (Denckla 1995) Provide for delayed responding Future-oriented Strategic action selection Intentionality Anticipatory Set Freedom from interference Ability to sequence behavioral outputs
27. Demand Situations for Executive Functions Multi-step tasks/ learning Novelty (lack of experience base) vs Automaticity (familiar) High vs low stress Future vs present orientation Intentional action selection
28. Outcome of “Good” Executive Function Purposeful, goal-directed activity Active problem solving Self-control Independence Reliability and consistency Positive self-efficacy Internal locus of control
30. Neuroanatomic Organization: Frontal lobes are densely connected with other cortical and subcortical regions Prefrontal system is highly, reciprocally interconnected with the limbic (motivational) system, reticular activating (arousal) system posterior association cortex (perceptual/ cognitive processes and knowledge base) motor (action) regions of the frontal lobes
31. Interventions: General Principles Teach goal-directed problem-solving process , within everyday meaningful routines, having real-world relevance and application, using key people (parents/ teachers/ peers) as models, “coaches” (Co-conductor).
32. Interventions: General Principles External to internal process External models of multi-step problem-solving routines External guidance to develop & implement everyday routines Practice application/ use of routines Fade external support to cueing internal generation & use of routines
33. Interventions: General Principles External to internal process Internal control to generate & use specific problem-solving routine Generalization to new situation, requiring some external guidance Accumulate experience, examine conditions for selective use of various routines Feedback throughout (i.e., reward)
34. Structuring an executive function intervention program Use of everyday routines with (e.g., Goal-Plan-Do-Review) Support working memory via “hard copy” of routine Allowing child to become increasingly more active in formulating plans and reviewing their performance
35. What Do We Hope to Learn? By using a developmental approach to analyzing both natural history and response to treatment we hope to discover information about . . . neurobehavioral/neuropsychological associations with localized dysfunction Age related differences in neurobehavioral/ neuropsychological sequelae Other phenomena such as how intervention might change the trajectory of development
36. What Do We Hope to Learn? Neuropsychological studies of UCD can help to identify specific effects on the brain associated with UCD and correlate these findings with behavior and outcome. The impact of UCD occurring at different stages of development will help us to better understand the impact of the disease process on the developing brain. The quantification of neuropsychological and neurobehavioral outcomes will be increasingly important in determining the efficacy of interventions. Efficacious educational/ behavioral interventions for children with UCD based on their neuropsychological profile.