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Question #27


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Questions and Answers

Question # 27

Do older children, adolescents, and adults with NLD exhibit deficits in "executive functions"? Are such deficits important dimensions of NLD?


Executive functions are much discussed in modern clinical neuropsychology. Although there are a number of definitions of these functions, they all appear to have in common the following components: (a) forming concepts; (b) solving complex problems; (c) discerning cause-effect relationships; (d) initiating, planning, directing, managing, and orchestrating behaviour. These executive functions are thought to develop especially quickly over the initial phases of the life-span, and many would ascribe the parallel (positively correlated) development of systems within the frontal lobes of the brain as responsible for, or causative in, the development of such functions. (Although important, this is an issue beyond the scope of this question.)

It is clear that older children, adolescents, and adults with NLD exhibit problems in concept-formation, problem-solving, discerning cause-and-effect relationships, and initiating, planning, directing, managing, and orchestrating their behaviour; these deficits are usually moderate to severe. This was known far before the term, executive functions, was coined. It has been known since the 1970s that persons who exhibit NLD usually display considerable difficulty in all aspects of complex concept-formation, reasoning, trouble-shooting, problem-solving, discerning cause-effect relationships, and related dimensions of behaviour. Indeed, our earliest formulations of NLD (e.g., Rourke, 1982; Strang & Rourke, 1983) placed considerable emphasis upon such deficits as pivotal to the understanding of the adaptive difficulties faced by persons with NLD.

Nothing has transpired since that time that would lead any serious scientist to question the validity of this point of view (e.g., Fisher, DeLuca, & Rourke, 1997). This is also the case for pediatric neurological disorders in which NLD is a predominant phenotype, such as Fragile X and Turner Syndromes (e.g., Kirk, Mazzocco, & Kover, 2005), spina bifida/hydrocephalus (Tarazi, Zabel, & Mohone, 2008), and Asperger's Syndrome (e.g., Kenworthy et al., 2005; Klin, Volkmar, Sparrow, Cicchetti, & Rourke, 1995; Rourke & Tsatsanis, 2000; Tsatsanis & Rourke, 2003). A review of investigations that deal with such phenotypic relationships in other forms of pediatric neurological disease, disorder, and dysfunction is contained in Rourke et al. (2002).

It is also the case that the impact of deficits in these important areas becomes more significant with the passing of time. With advancing years, many developmental demands change; chief among these is the expectation that the person will need less and less external structure to perform in an adaptive manner. Of course, this is not necessarily the case for the person with NLD, whose needs for structure may diminish very little with the passage of time. It is also expected that, with advancing years, the person will develop capacities for independent and age- appropriate decision-making. Once again, it is unlikely that the person with NLD will make significant strides in these areas or reach age-expected levels in them. Thus, the impact of the deficits under consideration is expected to become much more marked with advancing years from older childhood into adulthood (Ahmad, Rourke, & Drummond, under review; Rourke, Hayman-Abello, & Collins, 2003; Tsatsanis & Rourke, 2003).

Hence, the short answer to the first question is as follows: If one views executive functions as including the common dimensions cited above, yes. As for the second question, with regard to the importance of understanding of such dimensions vis-a-vis the adaptive behaviour of persons with NLD: Again, yes. Indeed, all of this has been well known for more than a quarter of a century.

Clinical Implications. Whereas the term, executive functions, has served to increase awareness of, and research regarding, the complexities of developmental brain-behaviour relationships, asserting that a particular person has deficiencies in "executive functions" is, arguably, not particularly helpful from either a classification/diagnostic or a treatment perspective. What is helpful is a determination of (a) whether and (b) to what extent a person has deficits in concept-formation, problem-solving, and so on. A comprehensive neuropsychological assessment is necessary in order to determine this. And, the efficacy of interventions for the person with NLD is very much dependent upon adequate inferences derived from an assessment of these dimensions within the context of other important neuropsychological assets and deficits.


References

Ahmad, S. A., Rourke, B. P., & Drummond, C. D. (under review). Comparison of older children and adults with Nonverbal Learning Disabilities and Basic Phonological Processing Disabilities.

Fisher, N. J., DeLuca, J. W., & Rourke, B. P. (1997). Wisconsin Card Sorting Test and Halstead Category Test performances of children and adolescents who exhibit the syndrome of Nonverbal Learning Disabilities. Child Neuropsychology, 3, 61-70.

Kenworthy, L. E., Black, D. O., Wallace, G. L., Ahlavalia, T., Wagner, Ann E., & Sirian, L. M. (2005). Disorganization: The forgotten executive dysfunction in high-functioning autism (HFA) spectrum disorders. Developmental Neuropsychology, 28, 809-828.

Kirk, J. W., Mazzocco, M. M., & Kover, S. T. (2005). Assessing executive dysfunction in girls with Fragile X or Turner Syndromes using the Contingency Naming Test (CNT). Developmental Neuropsychology, 28, 755-778.

Klin, A., Volkmar, F. R., Sparrow, S. S., Cicchetti, D. V., & Rourke, B. P. (1995). Validity and neuropsychological characterization of Asperger syndrome: Convergence with Nonverbal Learning Disabilities syndrome. Journal of Child Psychology and Psychiatry, 36, 1127-1140.

Rourke, B. P. (1982). Central processing deficiencies in children: Toward a developmental neuropsychological model. Journal of Clinical Neuropsychology, 4, 1-18.

Rourke, B. P., Ahmad, S. A., Collins, D. W., Hayman-Abello, B. A., Hayman-Abello, S. E., & Warriner, E. M. (2002). Child-clinical/pediatric neuropsychology: Some recent advances. Annual Review of Psychology, 53, 309-339.

Rourke, B. P., Hayman-Abello, B. A., & Collins, D. W. (2003). Learning disabilities: A neuropsychological perspective. In R. S. Schiffer, S. M. Rao, & B. S. Fogel (Eds.), Neuropsychiatry (2nd ed., pp. 630-659). New York: Lippincott, Williams, & Wilkins.

Rourke, B. P., & Tsatsanis, K. D. (2000). Syndrome of Nonverbal Learning Disabilities and Asperger syndrome. In A. Klin, F. Volkmar, & S. S. Sparrow (Eds.), Asperger syndrome (pp. 231-253). New York: Guilford Press.

Sikora, D. M., Haley, P., Edwards, J. & Butler, R. W. (2002). Tower of London test performance in children with poor arithmetic skills. Developmental Neuropsychology, 21(3), 243-254.

Strang, J. D., & Rourke, B. P. (1983). Concept-formation/non-verbal reasoning abilities of children who exhibit specific academic problems with arithmetic. Journal of Clinical Child Psychology, 12, 33-39.

Tarazi, R. A., Zabel, T. A., & Mahone, E. M. (2008). Age-related differences in executive function among children with spina bifida/hydrocephalus based on parent behavior. The Clinical Neuropsychologist, 22, 585-602.

Tsatsanis, K. D., & Rourke, B. P. (2003). Syndrome of Nonverbal Learning Disabilities: Effects on learning. In A. H. Fine & R. Kotkin (Eds,), Therapists guide to learning and attention disorders (pp. 109-145). New York: Academic Press.

Tsatsanis, K.D., & Rourke, B.P. (2008). Syndrome of Nonverbal Learning Disabilities in adults. In L. Wolf, H. Schreiber, & J. Wasserstein (Eds.), Adult learning disorders:Contemporary Issues.(pp.159-190). New York:Psychology Press.

Woodward, L. J., Caron, A. C. C., Pritchard, V. E., Anderson, P. J. & Inder, T. E. (2011). Neonatal white matter abnormalities predict global executive function impairment in children born very preterm. Developmental Neuropsychology, 36, 22-41.



Addendum: Scientific Notes and Background

From: Tsatsanis, K.D., & Rourke, B.P. (2008). Syndrome of Nonverbal Learning Disabilities in adults. In L. Wolf, H. Schreiber, & J. Wasserstein (Eds.), Adult learning disorders:Contemporary Issues.(pp.159-190). New York:Psychology Press.

In lieu of a strict one-to-one correspondence of structure and function, the functional role of brain regions may depend in part on the neural context or the pattern of interactions among brain regions. McIntosh (1999) gives evidence that a region, such as the right prefrontal cortex, can play a different functional role in memory depending upon its interactions with anatomically related regions. Rather than being committed to specific functions, brain regions may play a role in a variety of cognitive and other operations and that interregional interactions will differ depending on the type of cognitive challenge. It may be argued also that our own interpretation of the functionality of a region of the brain is dependent on context. Some brain regions are activated by several different tasks; tasks that belong to different cognitive domains may share processing components and thus activate overlapping regions (e.g., the role of the fusiform gyrus in activation to faces versus objects as part of a perceptual expertise network or a composition of the social brain; Schultz et al., 2003).

Finally, whereas a favorable area of research lies in “executive functions” and the role of the frontal lobe in the so-called executive brain, a consideration of the NLD model points to the importance of the somatosensory cortex and integration of sensory-perceptual networks in higher order thinking. Parietal regions in the right hemisphere are consistently activated during tasks involving attention, spatial perception and imagery, working memory, spatial episodic encoding, episodic retrieval, and skill learning (e.g., Cabeza & Nyberg, 2000, for a review). Moreover, neuro-imaging studies reveal that mental imagery, important to many cognitive tasks such as perspective changes and problem solving as well as motor leaning, may involve overlapping regions of the brain related to somato-sensory perception and actual experience (e.g., Wolbers, Weiller, & Buchel, 2003). Perhaps a neural parallel to Piaget’s developmental trajectories, attention to the spatial location of an object may engage overlapping regions responsible for tactile and guided visual motor (hand-arm) behavior. In their study, Wolbers et al. (2003) revealed that when mental rotation is combined with motor imagery of the hands, the superior parietal lobe is activated; this region is sensitive to signals arising from mental imagery in the absence of somatosensory input as well as to input in actual hand reaching and grasping. A task requiring a combination of visual spatial, tactile, and motor imagery is processed or integrated through activity in the parietal lobe; such functions can be expected to be impaired in NLD.

Similarly, a role for the right somatosensory cortex and emotion recognition is supported using lesion mapping (Adolphs, Damasio, Tranel, Cooper, & Damasio, 2000). The findings were significant for showing again that a seemingly visually based task, such as recognition of emotion from visually presented facial expressions, is significantly impaired by dysfunction in right-hemisphere regions processing somatosensory information. Moreover, distinct systems were critical for conceptual knowledge and knowledge of the name of an emotion versus knowledge based on one’s ability to recognize another’s emotional state by internally generating somatosensory representations that simulate how the other individual would feel when displaying a certain facial expression (e.g., based on one’s own internal experience). Connections between frontal regions and the right postcentral gyrus (somatosensory cortex) and regions of (right inferior) parietal lobe as well as the amygdala may be central to processing perspective or self-other distinctions (Ruby & Decety, 2004).

References

Adolphs, R., Damasio, H., Tranel. D., Cooper, G., & Damasio, A.R. (2000). A role for somatosensory cortices in the visual recognition of emotion as revealed by three-dimensional lesion mapping. The Journal of Neuroscience, 20, 2683-2690.

Cabeza, R., & Nyberg, L. (2000). Imaging cognition II: An empirical review of 275 PET and fMRI studies. Journal of Cognitive Neurosciences, 12, 1-47.

McIntosh, A. R. (1999). Mapping cognition to the brain through neural interactions. Memory, 7, 523-548.

Ruby, P., & Decety, J. (2004). How would you feel versus how do you think she would feel? A neuroimaging study of perspective-taking with social emotions. Journal of Cognitive Neuroscience, 16, 988-999.

Schultz, R.T., Grelotti, D.J., Klin, A., Kleinman, J., Van der Gaag, C., Marois, R., et al. (2003). The role of the fusiform face area in social cognition: Implications for the pathobiology of autism. Philosophical Transactions of the Royal Society, Series B., 358, 415-427.

Wolberg, T., Weiller, C., & Buchel, C. (2003). Contralateral coding of imagined body parts I the superior parietal lobe. Cerebral Cortex, 13, 392-399.


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