A comparison of working memory profiles in school-aged children with Specific Language Impairment, Attention Deficit/Hyperactivity Disorder, Comorbid SLI and ADHD and their typically developing peers

The association between specific language impairment (SLI), attention deficit/hyperactivity disorder (ADHD), and working memory (WM) was examined. WM has been implicated in language acquisition and models of ADHD; however, evidence for WM deficits in SLI and ADHD has been inconsistent. The components of Baddeley's WM model were investigated in 18 children with SLI, 16 children with ADHD, 11 children with comorbid SLI+ADHD, and 24 typically developing (TD) children. The presence of SLI resulted in deficits in more components of WM than the presence of ADHD indicating that children with SLI are more vulnerable to WM deficits than those with ADHD.     

Interactions between working memory and language in young children with specific language impairment (SLI)

The underlying structure of working memory (WM) in young children with and without specific language impairment (SLI) was examined. The associations between the components of WM and the language abilities of young children with SLI were then analyzed. The Automated Working Memory Assessment and four linguistic tasks were administered to 58 children with SLI and 58 children without SLI, aged 4–5 years. The WM of the children was best represented by a model with four separate but interacting components of verbal storage, visuospatial storage, verbal central executive (CE), and visuospatial CE. The associations between the four components of WM did not differ significantly for the two groups of children. However, the individual components of WM showed varying associations with the language abilities of the children with SLI. The verbal CE component of WM was moderately to strongly associated with all the language abilities in children with SLI: receptive vocabulary, expressive vocabulary, verbal comprehension, and syntactic development. These results show verbal CE to be involved in a wide range of linguistic skills; the limited ability of young children with SLI to simultaneously store and process verbal information may constrain their acquisition of linguistic skills. Attention should thus be paid to the language problems of children with SLI, but also to the WM impairments that can contribute to their language problems.     

What Part of Working Memory is not Working in ADHD? Short-Term Memory, the Central Executive and Effects of Reinforcement

Deficits in Working Memory (WM) are related to symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD). In children with ADHD visuospatial WM is most impaired. WM is composed of Short-Term Memory (STM) and a Central Executive (CE). Therefore, deficits in either or both STM and the CE may account for WM impairments in children with ADHD. WM-component studies investigating this find deficits in both STM and the CE. However, recent studies show that not only cognitive deficits, but also motivational deficits give rise to the aberrant WM performance of children with ADHD. To date, the influence of these motivational deficits on the components of WM has not been investigated. This study examined the effects of a standard (feedback-only) and a high level of reinforcement (feedback + 10 euros) on the visuospatial WM-, visuospatial STM-, and the CE performance of 86 children with ADHD and 62 typically-developing controls. With standard reinforcement the STM, CE, and WM performance of children with ADHD was worse than that of controls. High reinforcement improved STM and WM performance more in children with ADHD than in controls, but was unable to normalize their performance. High reinforcement did not appear to improve the CE-related performance of children with ADHD and controls. Motivational deficits have a detrimental effect on both the visuospatial WM performance and the STM performance of children with ADHD. Aside from motivational deficits, both the visuospatial STM and the CE of children with ADHD are impaired, and give rise to their deficits in visuospatial WM.     

Improving Working Memory in Children with Attention-Deficit/Hyperactivity Disorder: The Separate and Combined Effects of Incentives and Stimulant Medication

Working memory (WM) is considered a core deficit in Attention-Deficit/ Hyperactivity Disorder (ADHD), with numerous studies demonstrating impaired WM among children with ADHD. We tested the degree to which WM in children with ADHD was improved by performance-based incentives, an analog of behavioral intervention. In two studies, WM performance was assessed using a visuo-spatial n-back task. Study 1 compared children (ages 9-12?years) with ADHD-Combined type (n?=?24) to a group of typically developing (TD) children (n?=?32). Study 1 replicated WM deficits among children with ADHD. Incentives improved WM, particularly among children with ADHD. The provision of incentives reduced the ADHD-control group difference by approximately half but did not normalize WM. Study 2 examined the separate and combined effects of incentives and stimulant medication among 17 children with ADHD-Combined type. Both incentives and a moderate dose of long-acting methylphenidate (MPH; ~0.3?mg/kg t.i.d. equivalent) robustly improved WM relative to the no-incentive, placebo condition. The combination of incentives and medication improved WM significantly more than either incentives or MPH alone. These studies indicate that contingencies markedly improve WM among children with ADHD-Combined type, with effect sizes comparable to a moderate dose of stimulant medication. More broadly, this work calls attention to the role of motivation in studying cognitive deficits in ADHD and in testing multifactorial models of ADHD.     

Semantic Language as a Mechanism Explaining the Association between ADHD Symptoms and Reading and Mathematics Underachievement

ADHD is associated with academic underachievement, but it remains unclear what mechanism accounts for this association. Semantic language is an underexplored mechanism that provides a developmental explanation for this association. The present study will examine whether semantic language deficits explain the association between ADHD and reading and mathematics underachievement, taking into account alternative explanations for associations, including verbal working memory (WM) impairments, as well as specificity of effects to inattentive and hyperactive-impulsive ADHD symptom domains. Participants in this cross-sectional study were 546 children (54?% male) ages six to twelve (M?=?9.77, SD?=?1.49). ADHD symptoms were measured via maternal and teacher report during structured interviews and on standardized rating forms. Children completed standardized semantic language, verbal WM, and academic testing. Semantic language fully mediated the ADHD-reading achievement association and partially mediated the ADHD-mathematics achievement association. Verbal WM also partially mediated the ADHD-mathematics association but did not mediate the ADHD-reading achievement association. Results generalized across inattentive and hyperactive-impulsive ADHD symptom domains. Semantic language explained the association between ADHD and reading underachievement and partially explained the association between ADHD and mathematics underachievement. Together, language impairment and WM fully explained the association between ADHD and reading underachievement, in line with developmental models suggesting that language and WM conjointly influence the development of attention and subsequent academic achievement. This work has implication for the development of tailored interventions for academic underachievement in children with ADHD.     

Can Motivation Normalize Working Memory and Task Persistence in Children with Attention-Deficit/Hyperactivity Disorder? The Effects of Money and Computer-Gaming

Visual-spatial Working Memory (WM) is the most impaired executive function in children with Attention-Deficit/Hyperactivity Disorder (ADHD). Some suggest that deficits in executive functioning are caused by motivational deficits. However, there are no studies that investigate the effects of motivation on the visual-spatial WM of children with- and without ADHD. Studies examining this in executive functions other than WM, show inconsistent results. These inconsistencies may be related to differences in the reinforcement used. The effects of different reinforcers on WM performance were investigated in 30 children with ADHD and 31 non-ADHD controls. A visual-spatial WM task was administered in four reinforcement conditions: Feedback-only, 1 euro, 10 euros, and a computer-game version of the task. In the Feedback-only condition, children with ADHD performed worse on the WM measure than controls. Although incentives significantly improved the WM performance of children with ADHD, even the strongest incentives (10 euros and Gaming) were unable to normalize their performance. Feedback-only provided sufficient reinforcement for controls to reach optimal performance, while children with ADHD required extra reinforcement. Only children with ADHD showed a decrease in performance over time. Importantly, the strongest incentives (10 euros and Gaming) normalized persistence of performance in these children, whereas 1 euro had no such effect. Both executive and motivational deficits give rise to visual-spatial WM deficits in ADHD. Problems with task-persistence in ADHD result from motivational deficits. In ADHD-reinforcement studies and clinical practice (e.g., assessment), reinforcement intensity can be a confounding factor and should be taken into account. Gaming can be a cost-effective way to maximize performance in ADHD.     

Children with Comorbid Speech Sound Disorder and Specific Language Impairment are at Increased Risk for Attention-Deficit/Hyperactivity Disorder

This study focuses on the comorbidity between attention-deficit/hyperactivity disorder (ADHD) symptoms and speech sound disorder (SSD). SSD is a developmental disorder characterized by speech production errors that impact intelligibility. Previous research addressing this comorbidity has typically used heterogeneous groups of speech-language disordered children. This study employed more precise speech-language diagnostic criteria and examined ADHD symptomatology in 108 SSD children between the ages of 4 and 7 years old with specific language impairment (SLI) (n = 23, 14 males, 9 females) and without SLI (n = 85, 49 males, 36 females). We also examined whether a subcategory of SSD, persistent (n = 39, 25 males, 14 females) versus normalized SSD (n = 67, 38 males, 29 females), was associated with ADHD and/or interacted with SLI to predict ADHD symptomatology. Results indicated that participants in the SSD + SLI group had higher rates of inattentive ADHD symptoms than those in the SSD-only and control groups. In addition, an unexpected interaction emerged such that children with SLI and normalized-SSD had significantly higher ADHD inattentive ratings than the other subgroups. A proposed explanation for this interaction is discussed.     

Language Abilities in Children with Attention Deficit Hyperactivity Disorder, Reading Disabilities, and Normal Controls

Research has demonstrated a high prevalence of language impairments (LI) and reading disabilities (RD) in children with attention deficit hyperactivity disorder (ADHD). Since RD is also associated with LI, it is unclear whether the language impairments are specific to ADHD or associated with comorbid RD. The language abilities of ADHD children with and without RD were investigated in a task requiring recall of a lengthy narrative, and in tests assessing knowledge of the semantic aspects of language. The study was conducted with 50 boys—14 ADHD, 14 ADHD + RD, 8 RD, and 14 normal controls, aged 7 to 11. Children with ADHD (ADHD-only, ADHD + RD) exhibited difficulties in organizing and monitoring their story retelling. Children with RD (RD-only, ADHD + RD) demonstrated deficits in receptive and expressive semantic language abilities on the language processing tests. The comorbid group (ADHD + RD) exhibited the deficits of both ADHD and RD children. The deficiencies of ADHD children are consistent with higher-order executive function deficits while the deficits of RD children are consistent with deficits in the basic semantics of language processing.     

Working Memory and Motor Activity: A Comparison Across Attention-Deficit/Hyperactivity Disorder,Generalized Anxiety Disorder,and Healthy Control Groups

Converging findings from recent research suggest a functional relationship between attention-deficit/hyperactivity disorder (ADHD)-related hyperactivity and demands on working memory (WM) in both children and adults. Excessive motor activity such as restlessness and fidgeting are not pathognomonic symptoms of ADHD, however, and are often associated with other diagnoses such as generalized anxiety disorder (GAD). Further, previous research indicates that anticipatory processing associated with anxiety can directly interfere with storage and rehearsal processes of WM. The topographical similarity of excessive motor activity seen in both ADHD and anxiety disorders, as well as similar WM deficits, may indicate a common relationship between WM deficits and increased motor activity. The relationship between objectively measured motor activity (actigraphy) and PH and visuospatial WM demands in adults with ADHD (n = 21), adults with GAD (n = 21), and healthy control adults (n = 20) was examined. Although all groups exhibited significant increases in activity from control to WM conditions, the ADHD group exhibited a disproportionate increase in activity, while activity exhibited by the GAD and healthy control groups was not different. Findings indicate that ADHD-related hyperactivity is uniquely related to WM demands, and appear to suggest that adults with GAD are no more active relative to healthy control adults during a cognitively demanding laboratory task.     

Differences in memory functioning between children with attention-deficit/hyperactivity disorder and/or focal epilepsy

Prior research has shown that attention-deficit/hyperactivity disorder (ADHD) and epilepsy are frequently comorbid and that both disorders are associated with various attention and memory problems. Nonetheless, limited research has been conducted comparing the two disorders in one sample to determine unique versus shared deficits. Hence, we investigated differences in working memory (WM) and short-term and delayed recall between children with ADHD, focal epilepsy of mixed foci, comorbid ADHD/epilepsy and controls. Participants were compared on the Core subtests and the Picture Locations subtest of the Children’s Memory Scale (CMS). Results indicated that children with ADHD displayed intact verbal WM and long-term memory (LTM), as well as intact performance on most aspects of short-term memory (STM). They performed worse than controls on Numbers Forward and Picture Locations, suggesting problems with focused attention and simple span for visual-spatial material. Conversely, children with epilepsy displayed poor focused attention and STM regardless of the modality assessed, which affected encoding into LTM. The only loss over time was found for passages (Stories). WM was intact. Children with comorbid ADHD/epilepsy displayed focused attention and STM/LTM problems consistent with both disorders, having the lowest scores across the four groups. Hence, focused attention and visual-spatial span appear to be affected in both disorders, whereas additional STM/encoding problems are specific to epilepsy. Children with comorbid ADHD/epilepsy have deficits consistent with both disorders, with slight additive effects. This study suggests that attention and memory testing should be a regular part of the evaluation of children with epilepsy and ADHD.     

Noise on, voicing off: Speech perception deficits in children with specific language impairment

Speech perception of four phonetic categories (voicing, place, manner, and nasality) was investigated in children with specific language impairment (SLI) (n = 20) and age-matched controls (n = 19) in quiet and various noise conditions using an AXB two-alternative forced-choice paradigm. Children with SLI exhibited robust speech perception deficits in silence, stationary noise, and amplitude-modulated noise. Comparable deficits were obtained for fast, intermediate, and slow modulation rates, and this speaks against the various temporal processing accounts of SLI. Children with SLI exhibited normal “masking release” effects (i.e., better performance in fluctuating noise than in stationary noise), again suggesting relatively spared spectral and temporal auditory resolution. In terms of phonetic categories, voicing was more affected than place, manner, or nasality. The specific nature of this voicing deficit is hard to explain with general processing impairments in attention or memory. Finally, speech perception in noise correlated with an oral language component but not with either a memory or IQ component, and it accounted for unique variance beyond IQ and low-level auditory perception. In sum, poor speech perception seems to be one of the primary deficits in children with SLI that might explain poor phonological development, impaired word production, and poor word comprehension.     

Working memory and behavioral inhibition in boys with ADHD: An experimental examination of competing models

Working memory (WM) and behavioral inhibition impairments have garnered significant attention as candidate core features, endophenotypes, and/or associated neurocognitive deficits of attention-deficit/hyperactivity disorder (ADHD). The relationship between ADHD-related WM and inhibition deficits remains relatively unclear, however, with inferences about the constructs’ directional relationship stemming predominantly from correlational research. The current study utilized a dual-task paradigm to experimentally examine the relationship between ADHD-related WM and behavioral inhibition deficits. A total of 31 boys (15 ADHD and 16 typically developing [TD]) aged 8–12 years completed WM (1-back and 2-back), behavioral inhibition (stop-signal task [SST]), and dual-condition (1-back/SST and 2-back/SST) experimental tasks. Children with ADHD exhibited significant, large-magnitude WM deficits for the 1-back condition but were not significantly different from children in the TD group for the 2-back, 1-back/SST, and 2-back/SST conditions. Children with ADHD also exhibited significant inhibition deficits for the SST, 1-back/SST, and 2-back/SST conditions, but the within-group effect was not significant. The findings suggest that ADHD-related stop-signal demands are upstream, or compete for, resources involved in controlled-focused attention and/or other central executive (CE), WM processes.     

Content mazes and filled pauses in narrative language samples of children with specific language impairment

Linguistic nonfluencies known as mazes (filled pauses, repetitions, revisions, and abandoned utterances) have been used to draw inferences about processing difficulties associated with the production of language. In children with normal language development (NL), maze frequency in general increases with linguistic complexity, being greater in narrative than conversational contexts and in longer utterances. The same tendency has been found for children with specific language impairment (SLI). However, the frequency of mazes produced by children with NL and SLI has not been compared directly at equivalent utterance lengths in narration. This study compared the frequency of filled pauses and content mazes in narrative language samples of school-age children with SLI. The children with SLI used significantly more content mazes than the children with NL, but fewer filled pauses. Unlike content mazes, the frequency of filled pauses remained stable across samples of different utterance lengths among children with SLI. This indicates that filled pauses and content mazes have different origins and should not be analyzed or interpreted in the same way.     

What Causes Specific Language Impairment in Children?

ABSTRACT— Specific language impairment (SLI) is diagnosed when a child's language development is deficient for no obvious reason. For many years, there was a tendency to assume that SLI was caused by factors such as poor parenting, subtle brain damage around the time of birth, or transient hearing loss. Subsequently it became clear that these factors were far less important than genes in determining risk for SLI. A quest to find "the gene for SLI" was undertaken, but it soon became apparent that no single cause could account for all cases. Furthermore, although fascinating cases of SLI caused by a single mutation have been discovered, in most children the disorder has a more complex basis, with several genetic and environmental risk factors interacting. The clearest evidence for genetic effects has come from studies that diagnosed SLI using theoretically motivated measures of underlying cognitive deficits rather than conventional clinical criteria.     

Domain-specific cognitive systems: insight from Grammatical-SLI

Specific language-impairment (SLI) is a disorder of language acquisition in children who otherwise appear to be normally developing. Controversy surrounds whether SLI results from impairment to a "domain-specific" system devoted to language itself or from some more "domain-general" system. I compare these two views of SLI, and focus on three components of grammar that are good candidates for domain-specificity: syntax, morphology and phonology. I argue that the disorder is heterogeneous, and that deficits of different subgroups potentially stem from different underlying causes. Interestingly, although poor sensory or non-verbal abilities often co-occur with SLI, there is no evidence that these impairments cause the grammatical deficits found in SLI. Moreover, evidence suggests that impairment in at least one subgroup is specific to grammar.     

Sequence‐specific procedural learning deficits in children with specific language impairment

This study tested the procedural deficit hypothesis of specific language impairment (SLI) by comparing children's performance in two motor procedural learning tasks and an implicit verbal sequence learning task. Participants were 7‐ to 11‐year‐old children with SLI (n = 48), typically developing age‐matched children (n = 20) and younger typically developing children matched for receptive grammar (n = 28). In a serial reaction time task, the children with SLI performed at the same level as the grammar‐matched children, but poorer than age‐matched controls in learning motor sequences. When tested with a motor procedural learning task that did not involve learning sequential relationships between discrete elements (i.e. pursuit rotor), the children with SLI performed comparably with age‐matched children and better than younger grammar‐matched controls. In addition, poor implicit learning of word sequences in a verbal memory task (the Hebb effect) was found in the children with SLI. Together, these findings suggest that SLI might be characterized by deficits in learning sequence‐specific information, rather than generally weak procedural learning.     

Interrelations Between Executive Function and Symptoms of Hyperactivity/Impulsivity and Inattention in Preschoolers: A Two Year Longitudinal Study

The present study, including children at risk for developing Attention Deficit Hyperactivity Disorder (ADHD), examined the idea that complex executive functions (EFs) build upon more simple ones. This notion was applied in the study of longitudinal interrelations between core EF components — simple and complex inhibition, selective attention, and working memory (WM) — at age 5 and 6 as well as their predictive relations to ADHD symptoms at age 7. The results showed that simple inhibition and selective attention at age 5 independently predicted complex inhibition and WM at age 6. In addition, EFs primarily predicted symptoms of inattention rather than hyperactivity/impulsivity even at this young age. Finally, age 6 complex inhibition was shown to act as a mediator in the relations between simple inhibition and selective attention at age 5 and symptoms of inattention at age 7. These findings provide novel longitudinal support for the theory that fundamental EF components show a progression with age toward more complex executive control (see Garon et al. Psychological Bulletin 134(1):31–60 2008). Further, complex inhibition, implicating both inhibition and WM, seems to be a particularly strong correlate of ADHD symptoms in young children and should as such be the focus of future studies examining the relation between cognitive function and ADHD symptoms from a developmental perspective.     

Deficits in acquiring language structure: The importance of using prosodic cues

The study investigates and supports the hypothesis that (1) specifically language-impaired (SLI) children have deficits in processing and using the rhythmic-prosodic structure of speech; and that (2) these deficits impede the implicit learning of formal regularities of input language. The ability of SLI children to exploit prosodic cues in rule learning was tested in an experimental design using a miniature language. Twenty-four SLI children (mean age 6;5) learned a small set of sentences generated by a content-free rule system. The sample sentences were presented either with or without prosodic cues to the underlying formal regularities. The experimental groups were matched by various cognitive and language indicators. To assess whether they had acquired some regularities of the miniature language, a grammaticality judgement task was presented. In addition, their ability to reproduce rule-structured and rule-violating strings was tested. The experimental as well as some additional correlational data support the basic theoretical assumptions. The children had deficits in processing and exploiting prosodic cues in rule learning, and these deficits covaried with their rhythmic ability as indicated by a rhythm discrimination task.     

Working memory resources in young children with mathematical difficulties

Kyttälä, M., Aunio, P. & Hautamäki, J. (2010). Working memory resources in young children with mathematical difficulties. Scandinavian Journal of Psychology, 51 , 1–15.
Working memory (WM) ( Baddeley, 1986, 1997 ) is argued to be one of the most important cognitive resources underlying mathematical competence ( Geary, 2004 ). Research has established close links between WM deficits and mathematical difficulties. This study investigated the possible deficits in WM, language and fluid intelligence that seem to characterize 4- to 6-year-old children with poor early mathematical skills before formal mathematics education. Children with early mathematical difficulties showed poor performance in both verbal and visuospatial WM tasks as well as on language tests and a fluid intelligence test indicating a thoroughly lower cognitive base. Poor WM performance was not moderated by fluid intelligence, but the extent of WM deficits was related to language skills. The educational implications are discussed.     

The effects of presentation and content on syllogistic reasoning by children with and without specific language impairment

This study examines performance at a syllogistic reasoning task for a group of children (age 10 years) with specific language impairment (SLI) along with age- and language-matched controls. The syllogisms were presented either verbally or verbally/pictorially, and contained two types of item: imaginary versus real, both intended not to evoke strong beliefs. Children with SLI performed worse than age-matched controls, and equivalently to language-matched controls. Patterns of performance indicate this may be due to cognitive ability deficits rather than specific language deficits. For all groups, pictorial presentation interfered with reasoning processes. It is suggested that, for syllogisms, this pictorial information contextualises the interpretation of the task, and that in turn either raises working memory load or evokes belief bias. Additionally, these results suggest that caution should be exhibited before using visual aids to help children with SLI in the classroom.