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The relationship of a neuropsychological model of inhibitory control to the TOLDX performance of ADHD children
Abstracts from the 19th Annual Meeting
691
from the KABC), verbal reasoning (Similarities from the WISC-III), and language functioning (Peabody Picture Vocabulary Test-Revised, Formulated Sentences from the CELF-R). In terms of clock construction, four variables remained in the equation and successfully explained 43% of the variance in performance, including WCST Perseverative Errors and Failure to Maintain Set, Block Design, and the PPVT-R. In terms of hand placement, one variable remained in the equation and successfully explained 28% of the variance in performance: Gestalt Closure. Thus, it appears that children with A D H D present with poor clock drawing performance as compared to controls regardless of subtype, and executive functioning is a predictor of this reduced performance, along with visual-spatial functioning and receptive language.
Willen, E., Espe-Pfeifer, P., Devaraju-Backhaus, S., Mahrou, M., Michael, D., Golden, C., & Burns, W. J. An Analysis of Attention and Learning Deficits in A D H D and LD Children. This study investigated the utility of the Wide Range Assessment of Memory and Learning (WRAML) in identifying performance differences between children with Attention Deficit Hyperactivity Disorder (ADHD) and those with a learning disability (LD). Fifty-nine children with A D H D only and 66 children with LD only were included in the study. All children received a comprehensive neuropsychological evaluation and behavioral assessment prior to receiving the above diagnoses. No significant differences in performance between the two groups were found on three of the W R A M L Indices; the General Memory Index (GMI), Verbal Memory Index, and Visual Memory Index. However, A D H D children were found to score significantly higher on the Learning Index than LD children (F = 6.37, p < .0l) despite the fact that these two groups had similar IQs (as measured by the WISC-III) and similar GMI scores. The Learning Index measures the examinee's ability to acquire new information over multiple trials. Of the three subtests comprising this index, a significant difference was found on the Visual Learning subtest, with the LD children performing more poorly than those with A D H D (F = 4.97, p < .03). The reason that this subtest may have accounted for the significant finding on the Learning Index is because it is the most complex of the three subtests, and the demands of implicit memory may be greater. It is likely that, for the A D H D child, a learning difficulty is more an attentional rather than storage problem per se, whereas for the LD child it may be the reverse. The child with LD may attend well to the information presented, but still not be able to process this information adequately.
Cuibertson, W. C., Ziilmer, E. A., & Di Pinto, M. The Relationship of a Neuropsychological Model of Inhibitory Control to the TOL Dx Performance of A D H D Children. Numerous theoretical models have been proposed to account for the etiology, symptom manifestation, and response to treatment of childhood attention-deficit hyperactivity disorder (ADHD). Attention is currently centering on Barkley's (1997) model of A D H D as a disorder of self-regulation, namely impaired inhibitory control. Inhibitory control involves three interrelated neuropsychological processes: (a) inhibiting the initial prepotent response to an event; (b) stopping an ongoing response, thus allowing the delay necessary to decide whether the response should be altered or continued; and (c) protecting this period of delay from disruption by competing stimuli (resistance to distraction). Children exhibiting A D H D are hypothesized to manifest deficits in these three interrelated processes. The Tower of London-Drexel (TOL °x) is a measure of executive planning that has been found to differentiate A D H D and control children (Culbertson & Zillmer, 1998a,b). Multivariant analysis (factor analysis) has revealed that
692
Abstracts from the 19th Annual Meeting
T O L Dx planning performance is supported by a number of interrelated cognitive functions: response inhibition, working memory, attentional allocation, and mental flexibility. The relationship, however, of Barkley's tripartite inhibitory model to T O L Dx performance remains unclear. The purpose of the current study was to determine the relative contribution of each inhibitory process to the T O L Dx performance of children with A D H D . Measures were selected to assess inhibition of an initial prepotent response (Continuous Performance Test-commission error; CPTcm), stopping an ongoing response (Wisconsin Card Sorting Test-perseverative response; WCSTpsv), and resistance to interference (Stroop test-color-word; STRcw). Children identified with A D H D (n = 170), ranging in age from 8 to 15 years, were assessed with the inhibitory measures. Multiple regression analysis was employed to determine the relative contribution of each inhibitory measure to T O L Dx performance (total move, rule violation and time violation scores). Results revealed that the STRcw score contributed to the prediction of each of the T O L Dx scores. Specifically, the STRcw score combined with the CPTcm score in the prediction of total moves (R 2 = .48) and with the WCSTpsv score in the prediction of time violations ( R 2 = .44). Further, the STRcw score was found to be the singular predictor of rule violations (R 2 = .38). Thus, the three inhibitory processes contributed to T O L Dx performance in a differential manner with resistance to interference representing the primary inhibitory process. The results are discussed with regard to the executive-inhibitory deficits of ADHD~ models of inhibitory control and implicated neurosubstrates.
Hill, D., Campbell, R., Yeo, R., Brooks, W., Hart, B., & Vigil, J. Frontal-Striatal Circuitry in A D H D Children.
Previous MRI investigations have implicated frontal-striatal regions in the neuropathology of Attention Deficit Hyperactivity Disorder (ADHD). In the present study, 23 children with A D H D according to D S M - I V criteria and 24 normal control children underwent magnetic resonance imaging (MRI) of the brain. Volumetric measurements were obtained using the Measure program. Regions of interest included whole brain volume, dorsal-lateral prefrontal cortex (right/left), orbital prefrontal cortex, and caudate nucleus (right/left). Children with A D H D were found to have significantly reduced whole brain and total dorsal lateral prefrontal volumes, particularly on the right. No between-group differences emerged in orbital frontal or caudate volumes. Results of this study replicate previous findings of right frontal volumetric abnormalities in this population, and point to the right dorsal lateral region as particularly contributory to those abnormalities observed. In this study, lack of significant findings in caudate regions failed to clarify previous inconsistent findings regarding the role of the striatum in A D H D . Results of current study are discussed in relation to proposed pathophysiology of A D H D in the literature.
Hill, D., Campbell, R., Yeo, R., Vigil, J., Seeger, K., Bailey, R., & Yager, E. Working Memory and Executive Function in A D H D Children.
The present study utilized neuropsychological methods to assess memory and executive functions in children with Attention Deficit Hyperactivity Disorder (ADHD). Based on Barkley's proposed theory of A D H D , it was hypothesized that children with A D H D would perform significantly worse on tasks of visual and verbal working memory and that their performance would be related to performances on executive functioning measures. Twenty-five children diagnosed with A D H D according to D S M - I V criteria and 25 normal control children were administered a battery of tests including the Children's Consonant Trigrams, Sequential Memory Test, WISC-II1 Digit Span and Mazes subtests, Visual Two-Back Memory Task, Temporal Order Memory, W R A M L Story Memory and Verbal Learning subtests, visual CPT, Wisconsin Card Sorting Test, and Con-
691
from the KABC), verbal reasoning (Similarities from the WISC-III), and language functioning (Peabody Picture Vocabulary Test-Revised, Formulated Sentences from the CELF-R). In terms of clock construction, four variables remained in the equation and successfully explained 43% of the variance in performance, including WCST Perseverative Errors and Failure to Maintain Set, Block Design, and the PPVT-R. In terms of hand placement, one variable remained in the equation and successfully explained 28% of the variance in performance: Gestalt Closure. Thus, it appears that children with A D H D present with poor clock drawing performance as compared to controls regardless of subtype, and executive functioning is a predictor of this reduced performance, along with visual-spatial functioning and receptive language.
Willen, E., Espe-Pfeifer, P., Devaraju-Backhaus, S., Mahrou, M., Michael, D., Golden, C., & Burns, W. J. An Analysis of Attention and Learning Deficits in A D H D and LD Children. This study investigated the utility of the Wide Range Assessment of Memory and Learning (WRAML) in identifying performance differences between children with Attention Deficit Hyperactivity Disorder (ADHD) and those with a learning disability (LD). Fifty-nine children with A D H D only and 66 children with LD only were included in the study. All children received a comprehensive neuropsychological evaluation and behavioral assessment prior to receiving the above diagnoses. No significant differences in performance between the two groups were found on three of the W R A M L Indices; the General Memory Index (GMI), Verbal Memory Index, and Visual Memory Index. However, A D H D children were found to score significantly higher on the Learning Index than LD children (F = 6.37, p < .0l) despite the fact that these two groups had similar IQs (as measured by the WISC-III) and similar GMI scores. The Learning Index measures the examinee's ability to acquire new information over multiple trials. Of the three subtests comprising this index, a significant difference was found on the Visual Learning subtest, with the LD children performing more poorly than those with A D H D (F = 4.97, p < .03). The reason that this subtest may have accounted for the significant finding on the Learning Index is because it is the most complex of the three subtests, and the demands of implicit memory may be greater. It is likely that, for the A D H D child, a learning difficulty is more an attentional rather than storage problem per se, whereas for the LD child it may be the reverse. The child with LD may attend well to the information presented, but still not be able to process this information adequately.
Cuibertson, W. C., Ziilmer, E. A., & Di Pinto, M. The Relationship of a Neuropsychological Model of Inhibitory Control to the TOL Dx Performance of A D H D Children. Numerous theoretical models have been proposed to account for the etiology, symptom manifestation, and response to treatment of childhood attention-deficit hyperactivity disorder (ADHD). Attention is currently centering on Barkley's (1997) model of A D H D as a disorder of self-regulation, namely impaired inhibitory control. Inhibitory control involves three interrelated neuropsychological processes: (a) inhibiting the initial prepotent response to an event; (b) stopping an ongoing response, thus allowing the delay necessary to decide whether the response should be altered or continued; and (c) protecting this period of delay from disruption by competing stimuli (resistance to distraction). Children exhibiting A D H D are hypothesized to manifest deficits in these three interrelated processes. The Tower of London-Drexel (TOL °x) is a measure of executive planning that has been found to differentiate A D H D and control children (Culbertson & Zillmer, 1998a,b). Multivariant analysis (factor analysis) has revealed that
692
Abstracts from the 19th Annual Meeting
T O L Dx planning performance is supported by a number of interrelated cognitive functions: response inhibition, working memory, attentional allocation, and mental flexibility. The relationship, however, of Barkley's tripartite inhibitory model to T O L Dx performance remains unclear. The purpose of the current study was to determine the relative contribution of each inhibitory process to the T O L Dx performance of children with A D H D . Measures were selected to assess inhibition of an initial prepotent response (Continuous Performance Test-commission error; CPTcm), stopping an ongoing response (Wisconsin Card Sorting Test-perseverative response; WCSTpsv), and resistance to interference (Stroop test-color-word; STRcw). Children identified with A D H D (n = 170), ranging in age from 8 to 15 years, were assessed with the inhibitory measures. Multiple regression analysis was employed to determine the relative contribution of each inhibitory measure to T O L Dx performance (total move, rule violation and time violation scores). Results revealed that the STRcw score contributed to the prediction of each of the T O L Dx scores. Specifically, the STRcw score combined with the CPTcm score in the prediction of total moves (R 2 = .48) and with the WCSTpsv score in the prediction of time violations ( R 2 = .44). Further, the STRcw score was found to be the singular predictor of rule violations (R 2 = .38). Thus, the three inhibitory processes contributed to T O L Dx performance in a differential manner with resistance to interference representing the primary inhibitory process. The results are discussed with regard to the executive-inhibitory deficits of ADHD~ models of inhibitory control and implicated neurosubstrates.
Hill, D., Campbell, R., Yeo, R., Brooks, W., Hart, B., & Vigil, J. Frontal-Striatal Circuitry in A D H D Children.
Previous MRI investigations have implicated frontal-striatal regions in the neuropathology of Attention Deficit Hyperactivity Disorder (ADHD). In the present study, 23 children with A D H D according to D S M - I V criteria and 24 normal control children underwent magnetic resonance imaging (MRI) of the brain. Volumetric measurements were obtained using the Measure program. Regions of interest included whole brain volume, dorsal-lateral prefrontal cortex (right/left), orbital prefrontal cortex, and caudate nucleus (right/left). Children with A D H D were found to have significantly reduced whole brain and total dorsal lateral prefrontal volumes, particularly on the right. No between-group differences emerged in orbital frontal or caudate volumes. Results of this study replicate previous findings of right frontal volumetric abnormalities in this population, and point to the right dorsal lateral region as particularly contributory to those abnormalities observed. In this study, lack of significant findings in caudate regions failed to clarify previous inconsistent findings regarding the role of the striatum in A D H D . Results of current study are discussed in relation to proposed pathophysiology of A D H D in the literature.
Hill, D., Campbell, R., Yeo, R., Vigil, J., Seeger, K., Bailey, R., & Yager, E. Working Memory and Executive Function in A D H D Children.
The present study utilized neuropsychological methods to assess memory and executive functions in children with Attention Deficit Hyperactivity Disorder (ADHD). Based on Barkley's proposed theory of A D H D , it was hypothesized that children with A D H D would perform significantly worse on tasks of visual and verbal working memory and that their performance would be related to performances on executive functioning measures. Twenty-five children diagnosed with A D H D according to D S M - I V criteria and 25 normal control children were administered a battery of tests including the Children's Consonant Trigrams, Sequential Memory Test, WISC-II1 Digit Span and Mazes subtests, Visual Two-Back Memory Task, Temporal Order Memory, W R A M L Story Memory and Verbal Learning subtests, visual CPT, Wisconsin Card Sorting Test, and Con-