Investigating the relationship between attention and working memory in clinical and community samples

Does Working Memory Impact Functional Outcomes in Individuals With ADHD: A Qualitative and Comprehensive Literature Review

OBJECTIVE

Working Memory (WM) is a domain of executive functioning often impaired in individuals with ADHD. Although assumed to cause difficulties across functioning, the scope of impairments from WM deficits in ADHD has not been investigated. The aim of this study was to examine outcomes associated with WM deficits in ADHD.

METHOD

We conducted a search of the scientific literature on WM deficits, and Freedom From Distractibility (FFD), in ADHD using PubMed and PsycInfo databases.

RESULTS

The final sample included 11 controlled studies of WM/FFD deficits in ADHD with operationalized assessment of outcomes in academic, social, and emotional areas. WM assessment was divided into auditory-verbal memory (AVM) and spatial-visual memory (SWM). Seven studies examined WM deficits in academic functioning, eight studies assessed WM deficits in social functioning, and three assessed WM deficits in psychopathology.

CONCLUSION

The majority of the literature suggests that WM deficits affect primarily academic functioning.

The Relationship Between Executive Functions and Academic Performance in Primary Education: Review and Meta-Analysis

The purpose of this study was to research the relationship between executive functions and academic performance in primary education (6–12 years). Based on 21 samples (n = 7,947), a meta-analysis of random effects demonstrated a moderately significant weighted effect size (r = 0.365) and was found to be a good predictor of academic performance. For the subjects of language and mathematics, the results of the random effects model were similar and slightly higher for mathematics (r = 0.350; r = 0.365). Thus, the theory that executive functions have greater influence on mathematical performance is supported, especially in aspects such as coding, organization, and the immediate retrieval of information. Regarding the different executive function components (working memory, inhibition, cognitive flexibility, and planning), working memory had the highest presence (k = 14, n = 3,740) and predictive weight for performance, with an effect size of r = 0.370 for random effects, with a moderate level of significance. The moderating effect of variables such as gender and age were also analyzed. After performing a meta-regression, gender resulted in a value of R² = 0.49; the age variable was not significant. This result is especially important since age has traditionally been considered to be the moderating variable of executive functions. The review reveals a good predictive power of executive functions in the primary education stage, and it is even higher at the early ages, indicating its great significance in describing future performance. The study also revealed the competencies and specific aspects of the executive functions that affect the way in which its components intervene in the academic area, demonstrating the mediating effect of variables such as physical fitness, motor skills, and memory processes.

Applied Problem Solving in Children with ADHD: The Mediating Roles of Working Memory and Mathematical Calculation

The difficulties children with ADHD experience solving applied math problems are well documented; however, the independent and/or interactive contributions of cognitive processes underlying these difficulties are not fully understood and warrant scrutiny. The current study examines two primary cognitive processes integral to children's ability to solve applied math problems: working memory (WM) and math calculation skills (i.e., the ability to utilize specific facts, skills, or processes related to basic math operations stored in long-term memory). Thirty-six boys with ADHD-combined presentation and 33 typically developing (TD) boys aged 8-12 years old were administered multiple counterbalanced tasks to assess upper (central executive [CE]) and lower level (phonological [PH STM] and visuospatial [VS STM] short-term memory) WM processes, and standardized measures of mathematical abilities. Bias-corrected, bootstrapped mediation analyses revealed that CE ability fully mediated between-group differences in applied problem solving whereas math calculation ability partially mediated the relation. Neither PH STM nor VS STM was a significant mediator. When modeled together via serial mediation analysis, CE in tandem with math calculation ability fully mediated the relation, explained 79% of the variance, and provided a more parsimonious explication of applied mathematical problem solving differences among children with ADHD. Results suggest that interventions designed to address applied math difficulties in children with ADHD will likely benefit from targeting basic knowledge of math facts and skills while simultaneously promoting the active interplay of these skills with CE processes.

Generating Attention, Inhibition, and Memory: A Pilot Randomized Trial for Preschoolers With Executive Functioning Deficits

This goal of this study was to assess the initial feasibility and efficacy of a play-based intervention targeting executive functions (EF) and parent-child relationships in preschoolers compared with an active control group. Preschoolers with EF deficits (M age = 3.7 ± 0.47, predominantly White boys) and their parents were randomized to intervention (n = 36) or active control (n = 32) conditions. Child performance on EF tasks, parent and masked teacher ratings of EF and behavior, and masked clinician ratings of severity were collected at baseline and at 3 and 6 months postbaseline. Partial eta-squared effect sizes at .02 or higher comparing performance across the two groups was considered evidence of meaningful, albeit small, intervention effects. Intervention effects were observed for parent ratings of inattention, hyperactivity/impulsivity, and number/severity of problems experienced in various home situations, teacher ratings of severity of problems in various school situations, parent and teacher ratings of overall impairment, and clinician ratings of impairment. Intervention effects for functional improvements were maintained at the 6-month follow-up. No effect of the intervention was observed on the objective EF measures, although parent ratings of emotional control were improved for children in the intervention group. An intervention utilizing play-based activities targeting EF, when administered in a structured way by parents, is a promising approach for improving behavior in preschoolers with self-regulation deficits. More work is needed to investigate potential impact on EF and to disentangle mechanisms of action. It may be that the intervention's focus on the structure and quality of parent-child interactions is a mediator of outcomes, rather than improved EFs.

Clinical correlates of working memory deficits in youth with and without ADHD: A controlled study

OBJECTIVE

Both working memory (WM; a brain system that provides temporary storage and manipulation of the information) and attention-deficit/hyperactivity disorder (ADHD) have been associated with educational deficits. Since WM deficits are prevalent in children with ADHD, the main aim of the present study was to examine whether educational deficits are driven by working memory deficits or driven by the effect of ADHD itself.

METHOD

Participants were referred youth with (N = 276) and without (N = 241) ADHD ascertained from pediatric and psychiatric sources. Assessment included measures of psychiatric, psychosocial, educational, and cognitive functioning. Education deficits were defined as grade retention or placement in special classes and were assessed using interviews and written rating scales. Working memory was assessed using the Wechsler Intelligence Scale for Children-Revised (WISC-R) Freedom from Distractibility (FFD) factor based on Digit Span, Arithmetic, and Coding.

RESULTS

Significantly more youth with ADHD had WM deficits than controls (31.9% vs. 13.7%, p < .05). In ADHD children, WM deficits were significantly (p < .01) associated with an increased risk for grade retention and placement in special classes as well as lower scores on reading and math achievement tests than for ADHD children without WM deficits. In contrast, no other differences were noted in other areas of functioning. Although WM deficits also had some adverse impact on educational and cognitive correlates in non-ADHD controls, these differences failed to attain statistical significance.

CONCLUSION

WM deficits significantly and selectively increase the risk for academic deficits and cognitive dysfunction in children with ADHD beyond those conferred by ADHD. Screening for WM deficits may help identify children with ADHD at high risk for academic and cognitive dysfunction.

Comparison of change detection performance and visual search patterns among children with/without ADHD: Evidence from eye movements

BACKGROUND

ADHD participants showed poorer change detection performance compared to participants without any diagnosis. The difficulty to detect changes in ADHD children might be due to their voluntary eye movement control and attentional deficits.

AIMS

To evaluate change detection performance and visual search patterns of children with ADHD and compare their performances with typically developing (TD) children.

METHODS AND PROCEDURES

48 children (nADHD=24, nTD=24) participated (Mage=8 years, 10 months). Flicker paradigm was used to evaluate change detection performance, while eye movements were recorded during the experiment.

RESULTS

Change detection accuracies of TD children were higher compared to ADHD children. TD groups made longer fixations on the changed area and their first fixation duration was also longer than ADHD children which showed that TD children had longer fixation maintenance than ADHD children.

CONCLUSIONS

The change detection performance, which is associated with visual attention and memory, was found to be worse in ADHD children than TD children and these children made shorter fixations on the changed area than TD children. The findings were found to be in line with the difficulty to sustain attention in ADHD children that is necessary for encoding the scene properties and goal-oriented behavior.

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.

A longitudinal study of neuropsychological functioning and academic achievement in children with and without signs of attention-deficit/hyperactivity disorder

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) in childhood is associated with poor academic functioning. Deficits in academic functioning have proven to be less responsive to intervention than behavioral deficits in this population, yet the causes of this academic underperformance are not well understood. The purpose of this study is to examine the relationship between ADHD and academic performance in elementary-aged children in a developmental context. To do this, we study important cognitive variables and academic achievement over a three-year timeframe.

METHOD

Based on teacher ratings of ADHD, children were divided into a high symptom group (n = 17) and a low symptom group (n = 34). A thorough battery of cognitive and academic tests was administered at Time 1 and again 2 years later. Cognitive measures focused specifically on working memory and response inhibition.

RESULTS

RESULTS indicate that children who have high levels of ADHD signs differ from their low-sign peers in academic achievement and in several cognitive domains. Differences in cognitive functioning show a developmental trend consistent with earlier developmental delays in response inhibition and later delays in working memory. Working memory appears to be particularly important in several academic domains. Importantly, in a longitudinal model, working memory was more predictive of math achievement for students demonstrating signs of ADHD than for those who did not.

CONCLUSION

The relationship between these cognitive variables and academic functioning are explicated in the domains of reading, math, and problem solving.

Working memory in ADHD: a comparison of British and South African children

OBJECTIVE

The aim of the present study was to investigate the following issues: (a) Do students with ADHD have a pervasive pattern of impaired working memory skills across verbal and visuospatial domains? (b) is there evidence for a similar pattern of deficits across U.K. and South African students? and (c) which working memory tasks can effectively identify students with ADHD from TD peers?

METHOD

Four groups of children participated in the study: students with ADHD and TD from the United Kingdom and students with ADHD and TD from South Africa.

RESULTS

There were several key findings. First, the students with ADHD in South Africa performed significantly worse than the other groups (ADHD-United Kingdom, TD-United Kingdom, and TD-South Africa) in verbal and visuospatial short-term memory measures. Next, students with ADHD in the United Kingdom and South Africa exhibited working memory deficits extended to the visuospatial domain. This pattern was consistent with previous research in developmental populations (Alloway et al., 2006) and in adult samples (Kane et al., 2004; Park et al., 2002). A related finding was that the memory deficits in the students with ADHD (in the United Kingdom and South Africa) were significantly worse than their TD counterparts even when IQ and age were statistically accounted. These persistent deficits fit well accumulating evidence of the importance of working memory in learning.

CONCLUSION

Practical implications for education will be discussed in the context of appropriate diagnosis and support in the classroom.

The Contribution of Attentional Control and Working Memory to Reading Comprehension and Decoding

Little is known about how specific components of working memory, namely, attentional processes including response inhibition, sustained attention, and cognitive inhibition, are related to reading decoding and comprehension. The current study evaluated the relations of reading comprehension, decoding, working memory, and attentional control in 1,134 adolescent students. Path analyses were used to assess the direct and indirect effects of working memory and aspects of attentional control on reading comprehension and decoding. There were significant direct effects of working memory, sustained attention, and cognitive inhibition on reading comprehension, but not decoding. There was a significant direct effect of working memory and response inhibition on decoding, but not comprehension. These results suggest that different aspects of attentional control are important for decoding versus comprehension.

ADHD Subtype Differences in Reinforcement Sensitivity and Visuospatial Working Memory

Both cognitive and motivational deficits are thought to give rise to the problems in the combined (ADHD-C) and inattentive subtype (ADHD-I) of attention-deficit hyperactivity disorder (ADHD). In both subtypes one of the most prominent cognitive weaknesses appears to be in visuospatial working memory (WM), which is composed of short-term memory (STM) and a central executive (CE). In children with ADHD-C, both STM and the CE seem impaired, and together with motivational impairments, give rise to their deficits in visuospatial WM. In children with ADHD-I, no studies investigated these WM components and their interplay with motivational impairments. Effects of a standard (feedback only) and a high level of reinforcement (feedback + 10 euros) on visuospatial WM-, STM-, and CE performance were examined in 27 children with ADHD-I (restrictive-subtype), 70 children with ADHD-C, and 40 typically developing controls (aged 9-12). In both ADHD-subtypes CE and WM performance was worse than in controls. STM performance of children with ADHD-I was, in contrast to that of children with ADHD-C, not different from controls. STM and WM performance was worse in ADHD-C than in ADHD-I, whereas CE-related performance did not differ. High reinforcement improved STM and WM performance in both subtypes but not in controls. This improvement was equally pronounced in both subtypes. High reinforcement did not improve CE-related performance. Both subtypes have equally pronounced motivational deficits, which have detrimental effects on their visuospatial STM and WM performance. In contrast to children with ADHD-C, children with ADHD-I seem unimpaired on visuospatial STM; only an impaired CE and motivational impairments give rise to their deficits in visuospatial WM.

Executive function in children with attention deficit/hyperactivity disorder: the NIH EXAMINER battery

Theories of attention deficit/hyperactivity disorder (ADHD) increasingly highlight the role of neuropsychological impairment in ADHD; however, a consistent and identifiable pattern of performance on tests is not well established. The National Institutes of Health (NIH) Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (EXAMINER) battery provides measures of common variance across multiple executive function tests within specific domains and was used to characterize which executive functions are most affected in children with ADHD. Thirty-two children (24 male), ages 8-15 years (M = 12.02; SD = 2.29), diagnosed with ADHD and no comorbid disorder completed the NIH EXAMINER battery. Sixty age and gender matched healthy controls were chosen from a database of participants enrolled in the NIH EXAMINER multi-site study. Children with ADHD performed worse on the working memory score compared with the controls. No differences were found on the cognitive control or fluency scores. For children with ADHD, poorer working memory performance predicted parent report of child learning problems. Cognitive control and fluency scores did not predict learning problems. In summary, working memory emerges as a primary impairment in children with ADHD who have no comorbid disorders. Furthermore, working memory weaknesses may underlie the academic problems often seen in children with ADHD.

Working Memory: The What, the Why, and the How

Working memory, our ability to work with information, plays an important role in learning from kindergarten to the college years. In this article, we review the what, the why, and the how of working memory. First, we explore the relationship between working memory, short-term memory, and long-term memory. We also investigate research on the link between whether environmental factors, such as financial background and mother's educational level, affect working memory. In the next section — the why of working memory — we compare the predictive nature of working memory and IQ in learning outcomes. While IQ typically measures the knowledge acquired by the student, working memory measures what they do with that knowledge. Working memory skills are linked to key learning outcomes, including reading and math. In the final section, we present classroom strategies to support working memory. We also review current research on the efficacy of working memory training.

Moderators of working memory deficits in children with attention-deficit/hyperactivity disorder (ADHD): a meta-analytic review

Working memory has assumed a prominent role as a primary neurocognitive deficit or endophenotype in extant models of attention-deficit/hyperactivity disorder (ADHD). The current study updated previous reviews and employed meta-analytic techniques to examine a broad range of moderating variables of effect size heterogeneity across phonological and visuospatial working memory tasks. Collectively, results revealed large between-group effect sizes across both working memory domains. In addition, several sample (percent female) and task (number of experimental trials, recall vs. recognition tasks, and demands on the central executive) moderating variables explained significant effect size variability among phonological and visuospatial studies. These findings suggest that children with ADHD exhibit statistically significant, large magnitude working memory deficits relative to their typically developing peers.

Evaluating vigilance deficits in ADHD: a meta-analysis of CPT performance

We meta-analytically review 47 between-groups studies of continuous performance test (CPT) performance in children with attention-deficit/hyperactivity disorder (ADHD). Using a random effects model and correcting for both sampling error and measurement unreliability, we found large effect sizes (δ) for overall performance, but only small to moderate δ for performance over time in the handful of studies that reported that data. Smaller δs for performance over time are likely attributable, in part, to the extensive use of stimuli for which targets and distractors are quite easily differentiated. Artifacts accounted for a considerable proportion of variance among observed δs. Effect sizes reported in previous reviews were significantly attenuated because of the presence of uncorrected artifacts and highlight the necessity of accounting for artifactual variance in future work to determine the amount of true neurocognitive heterogeneity within ADHD. Signal detection theory and diffusion modeling analyses indicated that the ADHD-related deficits were because of decreased perceptual sensitivity (d') and slower drift rates (v). Results are interpreted the context of several recent models of ADHD.