Rhonda Martinussen

Working Memory Impairments in Children with Attention-Deficit Hyperactivity Disorder With and Without Comorbid Language Learning Disorders

Our objectives were to examine whether children with attention-deficit hyperactivity disorder (ADHD) are impaired on one or more components of working memory (WM) independent of comorbid language learning disorders, and whether WM impairments are more strongly related to symptoms of inattention than to symptoms of hyperactivity-impulsivity. Four groups of children participated: ADHD (n = 62); ADHD+RD/LI (n = 32); RD/LI (n = 15); and a typically developing comparison group (n = 34). Four simple and brief measures of WM were used that varied in modality (auditory-verbal; visual-spatial) and processing demands (temporary storage versus manipulation of information). Children with ADHD without comorbid language learning disorders exhibited deficits in visual-spatial storage and verbal and visual-spatial central executive (C.E.) functions that were independent of comorbid psychiatric disorders. Children with language learning disorders, regardless of comorbidity with ADHD, exhibited impairments in both verbal and spatial storage as well as C.E. domains of WM. Symptoms of inattention, but not symptoms of hyperactivity/impulsivity, predicted performance on verbal and visual-spatial C.E. measures independent of age, verbal cognitive ability, and reading and language performance. Findings are consistent with data implicating neuropsychological impairments in ADHD. The dimensional results are also consistent with prior research demonstrating the neuropsychological impairments are more strongly associated with the inattention symptom dimension than with the hyperactive-impulsive dimension.

Naming Speed Performance and Stimulant Effects Indicate Effortful, Semantic Processing Deficits in Attention-Deficit/Hyperactivity Disorder

This study investigated rapid automatized naming and effects of stimulant medication in school-age children with attention-deficit/hyperactivity disorder (ADHD) with and without concurrent reading disorder (RD). Two ADHD groups (67 ADHD only; 21 ADHD + RD) and a control group of 27 healthy age-matched peers were compared on four variables: color naming speed, letter naming speed, phonologic decoding, and arithmetic computation. Discriminant function analysis (DFA) was conducted to predict group membership. The four variables loaded onto two discriminant functions with good specificity: phonologic decoding, letter naming speed, and arithmetic defined the first function; color naming speed defined the second function. Both ADHD groups were significantly slower in color naming than controls, but did not differ from one another. DFA correctly classified 96% of the control group, 91% of ADHD + RD, and 82% of ADHD only. A subset of children in the ADHD groups participated subsequently in an acute, randomized, placebo-controlled, crossover trial with three single doses (10, 25, 20 mg) of methylphenidate. Methylphenidate selectively improved color-naming speed but had no effect on the speed of naming letters or digits. These findings challenge the tenet that naming speed deficits are specific to RD and implicate naming speed deficits associated with effortful semantic processing in ADHD, which are improved but not normalized by stimulant medication.

The Strengths and Difficulties Questionnaire overseas: evaluations and applications of the SDQ beyond Europe.

Abstract.Background:During the few years that have passed since it became available, the Strengths and Difficulties Questionnaire (SDQ) has been extensively evaluated and widely applied to assess behaviour disorders of children and adolescents in European countries. In contrast, relatively few reports have published SDQ results obtained in other parts of the world, although its briefness and availability in over 40 languages make this instrument particularly attractive for international collaborations and cross-cultural comparisons concerning clinical and epidemiological issues.Objectives:This initial overview summarises some of these non-European experiences with the SDQ by presenting a selection of projects that have either psychometrically evaluated this novel questionnaire, applied it to screen for behaviour disorders, or employed its parent-, teacher- or self-rated versions as research tools. Since a large part of the mentioned studies are ongoing or have only recently been completed, much of the work reported here is still unpublished.Conclusions:Across a huge variety of cultures and languages, experience gained with the SDQ in other continents has supported European evidence of good psychometric properties and clinical utility of this questionnaire. Since worldwide usage of the SDQ can be expected to increase in the future, more international coordination is encouraged, in order to fully exploit the promising potentials of this versatile assessment tool and systematically investigate cross-cultural differences and similarities in child and adolescent behaviour.

Methylphenidate Improves Visual-Spatial Memory in Children With Attention-Deficit/Hyperactivity Disorder

OBJECTIVE To investigate the effect of methylphenidate (MPH) on visual-spatial memory, as measured by subtests of the Cambridge Neuropsychological Testing Automated Battery (CANTAB), in children with attention-deficit/hyperactivity disorder (ADHD). Visual-spatial memory is a core component of working memory that has been shown to be impaired in ADHD, irrespective of comorbid reading and/or language problems. METHOD A clinic-referred sample of school-age children with a confirmed DSM-IV diagnosis of ADHD (n = 26) completed tests of visual-spatial memory, planning ability, and recognition memory in an acute, randomized, placebo-controlled, crossover trial with three single fixed doses of MPH. MPH effects on right-handed and left-handed motor control were also assessed. RESULTS MPH significantly improved performance on a self-ordered, updating visual-spatial working memory task and on maintenance of visual-spatial information but had no effects on measures of visual-spatial planning ability or recognition memory. Also, MPH significantly improved left-handed motor control. CONCLUSIONS Beneficial effects of MPH on visual-spatial processing in ADHD are selective and restricted to visual-spatial memory.

Working Memory Weaknesses in Students With ADHD: Implications for Instruction

Students with attention deficit hyperactivity disorder (ADHD) are at risk for academic underachievement. Children and youth with ADHD have been found to exhibit impairments on neuropsychological measures of executive functions, including working memory. Working memory is important to attentional control and learning. This article defines working memory, describes its importance to scholastic functioning, and highlights recent studies examining working memory functioning in students with ADHD. Finally, the authors discuss how educators can address working memory weaknesses in the classroom.

Word-level reading achievement and behavioral inattention: exploring their overlap and relations with naming speed and phonemic awareness in a community sample of children.

This study investigated the contribution of naming speed and phonemic awareness to teacher inattention ratings and word-level reading proficiency in 79 first grade children (43 boys, 36 girls). Participants completed the cognitive and reading measures midway through the school year. Teacher ratings of inattention were obtained for each child at the same time point. A path analysis revealed that behavioral inattention had a significant direct effect on word reading proficiency as well as significant indirect effects through phonemic awareness and naming speed. For pseudoword reading proficiency, the effects of inattention were indirect only through phonemic awareness and naming speed. A regression analysis indicated that naming speed, but not phonemic awareness, was significantly associated with teacher inattention ratings controlling for word reading proficiency. The findings highlight the need to better understand the role of behavioral inattention in the development of emergent literacy skills and reading proficiency.

Reading comprehension in adolescents with ADHD: Exploring the poor comprehender profile and individual differences in vocabulary and executive functions

The overall objective of this study was to investigate reading comprehension in youth with and without a prior diagnosis of attention-deficit hyperactivity disorder (ADHD). The first goal was to determine whether youth with and without ADHD matched in word reading ability exhibited differences in reading comprehension proficiency. The next goal was to determine whether good and poor comprehenders within the ADHD subgroup differed from each other on language and academic achievement measures. The third objective was to examine whether word recognition or oral vocabulary knowledge mediated the effect of ADHD symptoms on reading comprehension performance. Youth with ADHD scored significantly lower than the comparison youth on a standardized measure of reading comprehension. Relative to good comprehenders with ADHD, poor comprehenders with ADHD exhibited weaknesses in expressive vocabulary, mathematical reasoning, written expression, and exhibited more executive function (EF) difficulties as reported by the teacher. Expressive vocabulary and word reading, but not teacher EF ratings, accounted for unique variance in reading comprehension performance and mediated the relationship between ADHD symptoms and reading comprehension. Implications for further research and educational practice are discussed.

Longitudinal relations among inattention, working memory, and academic achievement: testing mediation and the moderating role of gender

Introduction. Behavioral inattention, working memory (WM), and academic achievement share significant variance, but the direction of relationships across development is unknown. The aim of the present study was to determine whether WM mediates the pathway between inattentive behaviour and subsequent academic outcomes. Methods. 204 students from grades 1–4 (49.5% female) were recruited from elementary schools. Participants received assessments of WM and achievement at baseline and one year later. WM measures included a visual-spatial storage task and auditory-verbal storage and manipulation tasks. Teachers completed the SWAN behaviour rating scale both years. Mediation analysis with PROCESS (Hayes, 2013) was used to determine mediation pathways. Results. Teacher-rated inattention indirectly influenced math addition fluency, subtraction fluency and calculation scores through its effect on visual-spatial WM, only for boys. There was a direct relationship between inattention and math outcomes one year later for girls and boys. Children who displayed better attention had higher WM scores, and children with higher WM scores had stronger scores on math outcomes. Bias-corrected bootstrap confidence intervals for the indirect effects were entirely below zero for boys, for the three math outcomes. WM did not mediate the direct relationship between inattention and reading scores. Discussion. Findings identify inattention and WM as longitudinal predictors for math addition and subtraction fluency and math calculation outcomes one year later, with visual-spatial WM as a significant mediator for boys. Results highlight the close relationship between inattention and WM and their importance in the development of math skills.

Factor Structure of the Strengths and Difficulties Questionnaire in a Canadian Elementary School Sample.

The Strengths and Difficulties Questionnaire (SDQ) is a 25-item screening measure for emotional and behavioral problems in children and adolescents aged 4 to 16. Structural equation modeling was used to test the five-factor structure of teacher and parent ratings on the British version of the SDQ in a community sample of 501 Canadian children aged 6 to 9 years. The five-factor model fit the data well for both teacher and parent ratings. In addition, the SDQ demonstrated acceptable reliability based on internal consistency coefficients and inter-rater agreement. The findings provide preliminary support for the reliability and validity of the British version of the parent and teacher SDQ in a sample of early elementary school Canadian children.

Combined Modality Intervention for ADHD with Comorbid Reading Disorders: A Proof of Concept Study.

To evaluate the relative efficacy of two reading programs with and without adjunctive stimulant medication for children with attention-deficit/hyperactivity disorder and comorbid reading disorder (ADHD+RD). Sixty-five children (7–11 years in age) were assigned randomly to one of three intensive remedial academic programs (phonologically or strategy-based reading instruction, or general academic strategy and social skills training) in combination with either immediate-release methylphenidate or placebo. Multiple-blind procedures were used for medication/placebo, given twice daily. Children received 35 hours of instruction in 10 weeks, taught by a trained teacher in a separate school classroom, in small matched groups of 2 to 3. Children’s behavior and reading abilities were assessed before and after intervention. Stimulant medication produced expected beneficial effects on hyperactive/impulsive behavioral symptoms (reported by classroom teachers) but none on reading. Children receiving a reading program showed greater gains than controls on multiple standardized measures of reading and related skills (regardless of medication status). Small sample sizes precluded interpretation of possible potentiating effects of stimulant medication on reading skills taught in particular reading programs. Intensive reading instruction, regardless of treatment with stimulant medication, may be efficacious in improving reading problems in children with ADHD+RD and warrants further investigation in a large-scale study.