Laurie E. Cutting

Prediction of Reading Comprehension: Relative Contributions of Word Recognition, Language Proficiency, and Other Cognitive Skills Can Depend on How Comprehension Is Measured.

Reading comprehension scores from the Wechsler Individual Achievement Tests, the Gates-MacGinitie Reading Test, and the Gray Oral Reading Test were examined in relation to measures of reading, language, and other cognitive skills that have been hypothesized to contribute to comprehension and account for comprehension differences. In a sample of 97 first through tenth graders, the relative contributions of word recognition/decoding and oral language skills to comprehension varied from test to test. The inclusion of reading speed accounted for additional variance, but prediction of comprehension scores was minimally improved by including measures of rapid serial naming, verbal memory, IQ, or attention. The findings suggest that commonly used tests of reading comprehension, such as the three we compared, may not tap the same array of cognitive processes. Implications for research and practice are discussed.

Validity of the behavior rating inventory of executive function in children with ADHD and/or Tourette syndrome

The dynamic, multidimensional nature of executive function (EF), thought to be characteristically impaired in those with attention deficit hyperactivity disorder (ADHD), has been challenging to operationalize and assess in a clinical setting [Barkley, R. A. (1997). ADHD and the nature of self-control. New York: Guilford Press.]. Gioia, Isquith, Guy, and Kenworthy [Gioia, G. A., Isquith, P. K., Guy, S. C., & Kenworthy, L. (2000) Behavior Rating Inventory of Executive Function. Odessa, FL: Psychological Assessment Resources.] developed the Behavior Rating Inventory of Executive Function (BRIEF) to address these concerns. In order to provide concurrent validity information on the BRIEF, parents of 76 children (ADHD=18; Tourette syndrome (TS)=21; TS+ADHD=17; controls=20) completed the BRIEF, additional behavior rating scales and interviews, measures of psychoeducational (PE) competence, and performance-based measures of EF. Both ADHD and TS+ADHD groups were rated as more impaired (P<.0001) than the other groups on the five primary BRIEF indices. BRIEF index scores showed no significant correlation with performance-based EF or PE measures, with the exception of math achievement; however, the BRIEF showed a strong relationship with interviews and other parent rating measures of behaviors seen in ADHD. Future attempts to validate the BRIEF should focus on differences within subtypes of ADHD (e.g., inattentive, combined subtypes), and separating ADHD from other clinical groups in which EF is reported to be a problem.

THE CONTRIBUTION OF EXECUTIVE SKILLS TO READING COMPREHENSION

Although word recognition deficits (WRD) are a known cause of reading comprehension deficits (RCD), other contributions to RCD, including executive function (EF), have not been fully explored. We examined the contribution of EF (working memory and planning), along with attention, decoding, fluency, and vocabulary to reading comprehension in 60 children (including 16 WRD and 10 RCD), ages 9–15 years. After controlling for commonly accepted contributors to reading comprehension (i.e., attention, decoding skills, fluency, and vocabulary), EF continued to make a significant contribution to reading comprehension but not to word recognition skills. These findings highlight the need for consideration of the role of EF in RCD.

Executive Dysfunction Among Children With Reading Comprehension Deficits

Emerging research supports the contribution of executive function (EF) to reading comprehension; however, a unique pattern has not been established for children who demonstrate comprehension difficulties despite average word recognition ability (specific reading comprehension deficit; S-RCD). To identify particular EF components on which children with S-RCD struggle, a range of EF skills was compared among 86 children, ages 10 to 14, grouped by word reading and comprehension abilities: 24 average readers, 44 with word recognition deficits (WRD), and 18 S-RCD. An exploratory principal components analysis of EF tests identified three latent factors, used in subsequent group comparisons: Planning/ Spatial Working Memory, Verbal Working Memory, and Response Inhibition. The WRD group exhibited deficits (relative to controls) on Verbal Working Memory and Inhibition factors; S-RCD children performed more poorly than controls on the Planning factor. Further analyses suggested the WRD group’s poor performance on EF factors was a by-product of core deficits linked to WRD (after controlling for phonological processing, this group no longer showed EF deficits). In contrast, the S-RCD group’s poor performance on the planning component remained significant after controlling for phonological processing. Findings suggest reading comprehension difficulties are linked to executive dysfunction; in particular, poor strategic planning/organizing may lead to reading comprehension problems.

Effects of fluency, oral language, and executive function on reading comprehension performance

Reading disability (RD) typically consists of deficits in word reading accuracy and/or reading comprehension. While it is well known that word reading accuracy deficits lead to comprehension deficits (general reading disability, GRD), less is understood about neuropsychological profiles of children who exhibit adequate word reading accuracy but nevertheless develop specific reading comprehension deficits (S-RCD). Establishing the underlying neuropsychological processes associated with different RD types is essential for ultimately understanding core neurobiological bases of reading comprehension. To this end, the present study investigated isolated and contextual word fluency, oral language, and executive function on reading comprehension performance in 56 9- to 14-year-old children [21 typically developing (TD), 18 GRD, and 17 S-RCD]. Results indicated that TD and S-RCD participants read isolated words at a faster rate than participants with GRD; however, both RD groups had contextual word fluency and oral language weaknesses. Additionally, S-RCD participants showed prominent weaknesses in executive function. Implications for understanding the neuropsychological bases for reading comprehension are discussed.

Effects of IQ on Executive Function Measures in Children with ADHD

The present study compared children with Attention-Deficit Hyperactivity Disorder (ADHD) and controls on a selected set of clinical measures of executive function (EF). A total of 92 children (51 ADHD, 41 control), ages 6-16, completed measures chosen from a larger neuropsychological battery to illustrate diverse components of the EF construct (planning, inhibitory control, response preparation, memory search). The selected measures were moderately correlated with one another, and moderately correlated with IQ. After controlling for age, sex, presence of learning disability (LD), ADHD, and IQ test version, Full Scale IQ was significantly related to four of the five selected EF measures. A second analysis showed group differences on the EF measures at different IQ levels. After covarying for age, there was a significant multivariate effect for IQ level (average, high average, superior) and a significant multivariate interaction between group (ADHD vs. control) and IQ level. Three of the five selected EF measures showed significant univariate group effects (controls performing better than ADHD) at the average IQ level; however, there were no significant group differences between children with ADHD and controls at high average or superior IQ levels. These results suggest that clinical measures of EF may differ among children with ADHD and controls at average IQ levels, but there is poorer discriminatory power for these measures among children with above average IQ.

Sex differences in cerebral laterality of language and visuospatial processing

Sex differences on language and visuospatial tasks are of great interest, with differences in hemispheric laterality hypothesized to exist between males and females. Some functional imaging studies examining sex differences have shown that males are more left lateralized on language tasks and females are more right lateralized on visuospatial tasks; however, findings are inconsistent. Here we used functional magnetic resonance imaging to study thirty participants, matched on task performance, during phonological and visuospatial tasks. For each task, region-of-interest analyses were used to test differences in cerebral laterality. Results indicate that lateralization differences exist, with males more left lateralized during the phonological task and showing greater bilateral activity during the visuospatial task, whereas females showed greater bilateral activity during the phonological task and were more right lateralized during the visuospatial task. Our data provide clear evidence for differences in laterality between males and females when processing language versus visuospatial information.

White matter microstructural differences linked to left perisylvian language network in children with dyslexia.

Studies of dyslexia using diffusion tensor imaging (DTI) have reported fractional anisotropy (FA) differences in left inferior frontal gyrus (LIFG) and left temporo-parietal white matter, suggesting that impaired reading is associated with atypical white matter microstructure in these regions. These anomalies might reflect abnormalities in the left perisylvian language network, long implicated in dyslexia. While DTI investigations frequently report analyses on multiple tensor-derived measures (e.g., FA, orientation, tractography), it is uncommon to integrate analyses to examine the relationships between atypical findings. For the present study, semi-automated techniques were applied to DTI data in an integrated fashion to examine white matter microstructure in 14 children with dyslexia and 17 typically developing readers (ages 7-16 years). Correlations of DTI metrics (FA and fiber orientation) to reading skill (accuracy and speed) and to probabilistic tractography maps of the left perisylvian language tracts were examined. Consistent with previous reports, our findings suggest FA decreases in dyslexia in LIFG and left temporo-parietal white matter. The LIFG FA finding overlaps an area showing differences in fiber orientation in an anterior left perisylvian language pathway. Additionally, a positive correlation of FA to reading speed was found in a posterior circuit previously associated with activation on functional imaging during reading tasks. Overall, integrating results from several complementary semi-automated analyses reveals evidence linking atypical white matter microstructure in dyslexia to atypical fiber orientation in circuits implicated in reading including the left perisylvian language network.

Oculomotor abnormalities in attention deficit hyperactivity disorder: A preliminary study

Background: Prevailing hypotheses suggest that attention deficit hyperactivity disorder (ADHD) is secondary to dysfunction of motor intentional systems mediated by prefrontal circuitry. Oculomotor paradigms provide a mechanism for examining and localizing dysfunction at the interface between movement and cognition. Objective: Three different saccade tasks (reflexive or prosaccades, antisaccades, and memory-guided saccades) were used to examine functions necessary for the planning and the execution of eye movements, including motor response preparation, response inhibition, and working memory. Methods: The study included 19 children with ADHD, divided into two groups: a group of 8 children on methylphenidate at the time of testing and a group of 11 children not taking any psychoactive medication. Results from the two groups were compared with those from 25 age- and gender-matched normal control children. Results: Both groups of children with ADHD made significantly more directional errors than did controls on the antisaccade task and significantly more anticipatory errors than did controls on the memory-guided saccade task, findings that are consistent with deficits in response inhibition. There were no significant differences in prosaccade latency, although unmedicated children with ADHD showed significantly greater variability in latency on the prosaccade task than did controls. On the memory-guided saccade task there were no significant differences in saccade accuracy; however, unmedicated children with ADHD showed longer saccade latency than did either controls or medicated children with ADHD. Conclusions: Oculomotor findings suggest that deficits in prefrontal functions, in particular response inhibition, contribute to behavioral abnormalities observed in ADHD. Findings also suggest that the administration of methylphenidate is associated with improvements in the consistency of motor response. Although there were no observed improvements in response inhibition with methylphenidate, conclusions await a design in which subjects complete testing both on and off medication.

Disproportionate increases of white matter in right frontal lobe in Tourette syndrome.

Objective: Based on previous findings implicating abnormalities of cortico–striatal–thalamo–cortical circuitry in Tourette syndrome (TS), the authors performed a volumetric analysis of frontal and nonfrontal tissue (gray + white matter) in boys with TS, with and without attention deficit hyperactivity disorder (ADHD). Methods: Frontal and nonfrontal gray and white matter compartment volumes, obtained by a MRI protocol, were analyzed with a 2 × 2 factorial multivariate analysis of variance approach for associations with a TS or ADHD factor in 11 boys with TS only, 14 with TS + ADHD, 12 with ADHD only, and 26 healthy boys. Results: In subjects with TS, the right frontal lobe showed a larger proportion of white matter. In addition, results were consistent with previous reports of reduced frontal lobe volumes associated with ADHD. Our analyses suggested these reductions to be mainly the consequence of smaller gray matter volumes, particularly on the left. Conclusions: These findings, suggesting the volumetric composition of frontal lobe tissue to be different in TS, support the hypothesis proposing frontostriatal pathway involvement in the pathophysiology of the disorder. Differences in composition of right frontal lobe attributable to white matter do not definitively implicate the hypothesized fiber pathways; however, considered in the context of the unilateral directionality of frontal–striatal circuitry, these results suggest the white matter connections as one explanation for basal ganglia anomalies (loss of normal left > right asymmetry) in TS.