A meta-analysis of working memory impairments in children with attention-deficit/hyperactivity disorder

Investigating Working Memory Deficits in School-Age Children with Attention-Deficit/Hyperactivity Disorder: An Event-Related Potentials Study During Delayed-Match-to-Sample Task

OBJECTIVE

To investigate the neural mechanisms underlying working memory (WM) deficits in children with ADHD.

METHOD

WM was compared between thirty-four children with ADHD and thirty-four matched controls using neuropsychological tests, spatial and verbal versions of modified delayed matching-to-sample (DMTS) tasks, and the event-related potential technique.

RESULTS

Children with ADHD demonstrated poor behavioral performance, delayed P3 latencies in high-load spatial modified DMTS tasks during encoding, and delayed P2 and N2 latencies during retrieval in spatial modified DMTS tasks. In high-load verbal modified DMTS tasks during encoding, they showed a smaller P3 amplitude.

DISCUSSION

Pronounced deficits in the central executive system in children with ADHD were exhibited by neuropsychological tests and the modified DMTS task. Children with ADHD exhibited a slowing of processing speed during encoding. Under high-load conditions, they showed a reduced P3 amplitude during retrieval, suggesting reduced neural resource allocation was available when the central executive of the working memory was heavily loaded.

Neuromonitoring-guided working memory intervention in children with ADHD

We proposed a personalized intervention that integrates computerized working memory (WM) training with real-time functional neuromonitoring and neurofeedback (NFB) to enhance frontoparietal activity and improve cognitive and clinical outcomes in children with attention-deficit/hyperactivity disorder (ADHD). The study involved 77 children with ADHD aged 7-11 years, who were assigned to either 12 sessions of NFB or treatment-as-usual (i.e., received standard clinical care) groups. Real-time neuromonitoring with functional near-infrared spectroscopy (fNIRS) and fMRI measured frontoparietal activity during n-back task at baseline and post-intervention. Thirty-six participants (21 NFB, 15 treatment-as-usual) completed the study. Significant improvements in NFB group were observed in frontoparietal brain activity and WM performance (primary outcomes). NFB group also showed improvements in Behavior Rating Inventory of Executive Function (BRIEF-2) WM t-scores and Conners 3 ADHD index scores (secondary outcomes) compared to treatment-as-usual group. These findings suggest that neuromonitoring-guided NFB effectively enhances cognitive and clinical outcomes in children with ADHD by targeting brain mechanisms underlying WM deficits.

No Effects of Auditory and Visual White Noise on Oculomotor Control in Children with ADHD

BACKGROUND

White noise stimulation has demonstrated efficacy in enhancing working memory in children with ADHD. However, its impact on other executive functions commonly affected by ADHD, such as inhibitory control, remains largely unexplored. This research aims to explore the effects of two types of white noise stimulation on oculomotor inhibitory control in children with ADHD.

METHOD

Memory guided saccade (MGS) and prolonged fixation (PF) performance was compared between children with ADHD (N = 52) and typically developing controls (TDC, N = 45), during auditory and visual white noise stimulation as well as in a no noise condition.

RESULTS

Neither the auditory nor the visual white noise had any beneficial effects on performance for either group.

CONCLUSIONS

White noise stimulation does not appear to be beneficial for children with ADHD in tasks that target oculomotor inhibitory control. Potential explanations for this lack of noise benefit will be discussed.

Executive function in children with neurodevelopmental conditions: a systematic review and meta-analysis

Executive function (EF) delays are well documented in paediatric neurodevelopmental conditions (NDCs). There is no consensus about whether EF delay represents a transdiagnostic feature of NDCs. This systematic review and meta-analysis synthesized 180 studies reporting two or more NDC comparisons on EF, examined differences between NDCs, and the moderating effects of gender, age, publication year, DSM editions and assessment types. Studies using established EF measures across seven domains (attention, fluency, set-shifting, set-switching, response inhibition, planning and working memory) in participants under 18 were included. Summary effects were compared: (1) for all reported NDCs relative to control, (2) for each individual NDC relative to control and (3) between NDC groups. Results confirmed that EF delay was a transdiagnostic feature of neurodevelopmental delay, with a moderate effect size of delay across all NDCs (g = 0.56, 95% confidence interval (CI) 0.49-0.63) compared with control. This effect increased with comorbidities (g = 0.72, 95% CI 0.59-0.86), DSM-5 criteria and informant measures. Comparisons between NDCs revealed few differences: children with tic disorders (TD) showed smaller EF delays, children with attention-deficit/hyperactivity disorder (ADHD) showed larger delays in attention, response inhibition, planning and working memory compared with TD and specific learning disorders, while children with autism spectrum disorders showed greater delays on set-switching compared with ADHD. Findings support transdiagnostic models of neurodevelopment to further a developmentally sensitive science that can reveal how EF delays contribute to brain circuitry, symptom profiles and functioning, and ultimately support early interventions and outcomes for all children with NDCs.

Eye-tracking training improves visuospatial working memory of children with attention-deficit/hyperactivity disorder and autism spectrum disorder

Given the close connection between eye movement and frontal lobe functions and some evidence supporting the effect of eye-tracking training on enhancing cognitive performance mediated by the frontal lobe, this study aimed to explore if after-school eye-tracking training can improve the visuospatial working memory (VSWM) and cognitive flexibility performance in children with attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). This study is a non-randomized cluster trial. Forty children from eight primary schools were selected, half receiving eye-tracking training for 20 sessions over 9 months, while the other half served as a waitlist control. They were matched on demographic characteristics and baseline cognitive performance. Their VSWM and cognitive flexibility were assessed at the beginning and end of the study. Results showed that children who received eye-tracking training, but not those on a waitlist, exhibited significant improvements in the total score and working memory span of the VSWM tests, and the correct responses in cognitive flexibility tests. Specifically, VSWM performance at higher span levels (5 or above) yielded a greater improvement. The findings suggest that eye-tracking training can be a feasible and effective after-school program for improving working memory and cognitive flexibility performance in children with ADHD and ASD. This study was prospectively registered at ClinicalTrials.gov (https://clinicaltrials.gov/, trial number: NCT05428657).

Is WISC-IV Working Memory Index associated with ADHD symptoms in 7-8-year-olds?

The Working Memory Index (WMI) in the Wechsler Intelligence Scale for Children (WISC) has been suggested to be associated with ADHD symptoms. The relationship between WMI and ADHD symptoms in the general population is not clear. The study aimed to examine the association between working memory (WM) and behavioral regulation (BR), and hyperactivity/inattention (HI) in a general population sample of 7-8-year-olds, and whether general intellectual functioning is associated with BR and HI. The study also examined if those with low WMI also fulfill elevated ADHD criteria. The study group (N = 865) was assessed with the WISC (Fourth edition), the Behavior Rating Inventory of Executive Function, the Strengths and Difficulties Questionnaire, and the Five to Fifteen Questionnaire, and divided into three groups based on WM function, and in relation to BR and/or HI problems. The associations between WM and BR, and WM and HI, including intellectual functioning as covariate, were examined. WM deficits were found in 22%, but the majority of those had no BR or HI problems. Four percent in the study group had WM deficits combined with BR and/or HI problems, and in about one third of those inattentive ADHD criteria were fulfilled. WM and prosocial behavior were associated with BR and HI. WM deficits measured with WISC WMI in 7-8-year-olds do not always signal BR and/or HI problems.

Effects of Auditory and Visual White Noise on Oculomotor Inhibition in Children With Attention-Deficit/Hyperactivity Disorder: Protocol for a Crossover Study

BACKGROUND

In attention-deficit/hyperactivity disorder (ADHD), poor inhibitory control is one of the main characteristics, with oculomotor inhibition impairments being considered a potential biomarker of the disorder. While auditory white noise has demonstrated the ability to enhance working memory in this group, visual white noise is still unexplored and so are the effects of both types of white noise stimulation on oculomotor inhibition.

OBJECTIVE

This crossover study aims to explore the impact of auditory and visual white noise on oculomotor inhibition in children with ADHD and typically developing (TD) children. The study will investigate the impact of different noise levels (25% and 50% visual, 78 dB auditory), and performance will be evaluated both with and without noise stimulation. We hypothesize that exposure to white noise will improve performance in children with ADHD and impair the performance for TD children.

METHODS

Memory-guided saccades and prolonged fixations, known for their sensitivity in detecting oculomotor disinhibition in ADHD, will be used to assess performance. Children diagnosed with ADHD, withdrawing from medication for 24 hours, and TD children without psychiatric disorders were recruited for the study.

RESULTS

Data collection was initiated in October 2023 and ended in February 2024. A total of 97 participants were enrolled, and the first results are expected between September and November 2024.

CONCLUSIONS

This study will examine whether cross-modal sensory stimulation can enhance executive function, specifically eye movement control, in children with ADHD. In addition, the study will explore potential differences between auditory and visual noise effects in both groups. Our goal is to identify implications for understanding how noise can be used to improve cognitive performance.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06057441; https://clinicaltrials.gov/study/NCT06057441.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/56388.

Attention-deficit/hyperactivity disorder (ADHD) in cultural context II: a comparison of the links between ADHD symptoms and waiting-related responses in Hong Kong and UK

The concept of attention-deficit/hyperactivity disorder (ADHD) is considered to have cross-cultural validity, but direct comparisons of its psychological characteristics across cultures are limited. This study investigates whether preschool children's ADHD symptoms expressed in two cultures with different views about child behaviour and parenting, Hong Kong and the UK, show the same pattern of associations with their waiting-related abilities and reactions, an important marker of early self-regulation. A community sample of 112 preschoolers (mean age = 46.22 months; 55 from UK, 57 from HK) completed three tasks measuring different waiting elements - waiting for rewards, choosing the amount of time to wait, and having to wait unexpectedly when a task is interrupted. Participants' waiting-related behavioural and emotional reactions were coded. Parents rated their children's ADHD symptoms and delay aversion. Our findings revealed that the associations between ADHD symptoms and waiting-related responses were comparable in both UK and HK samples. This suggests that the core psychological characteristics of ADHD, particularly in relation to waiting behaviours, may exhibit similarity across cultural contexts. Future research can extend this cross-cultural analysis to other ADHD-related psychological domains and explore additional cultural settings.

Examining the role of the visuospatial sketchpad in children's math calculation skills using Baddeley and Hitch's model of working memory

Math difficulties (MDs) occur in about 3-7 % of children and have been associated with academic, health, and occupational challenges. To date, findings about the role of working memory in MDs have been conflicting. The Automated Working Memory Assessment Battery (AWMA), which assesses all components of Baddeley and Hitch's model of working memory, was used to investigate which component of the model was most related to math calculation skills in elementary-school children. Participants were 94 (52 male) children (M age = 9 years 1 month; Range = 6 years 0 months to 11 years 8 months). As hypothesized, math calculation scores were correlated with all four working memory components (phonological loop, visuospatial sketchpad, verbal and visuospatial central executive). After accounting for age, phonological processing, and attention, the visuospatial sketchpad was the only memory component that contributed to the prediction of math calculation scores, explaining an additional 10.2 % of unique variance. Short-term visuospatial memory should be assessed in children having difficulty with math and children could benefit from interventions that include attention to the development of both visuospatial memory and math calculation skills. This study did not use a longitudinal design and so we cannot conclude that weak visuospatial memory impedes the development of math calculation skills. Future research should use longitudinal designs and investigate other types of math skills.

Contextualizing Positionality, Intersectionality, and Intelligence in the Anthropocene

The geological epoch of the Anthropocene has challenged traditional definitions of what intellectual abilities are necessary to creatively problem-solve, understand, and address contemporary societal and environmental crises. If we hope to make meaningful changes to how our society addresses these complex issues and pave the way for a better future for generations to come, we must advance traditional theories and measures of higher-order abilities to reflect equity and inclusion. To this end, we must address global issues by integrating the complexities of intersectional identities as they impact our understanding of what constitutes intelligence in individuals, groups, and diverse communities. This re-envisioning of intelligence presents new complexities for understanding and challenges for our field beyond the boundaries of what has been previously touted by many disciplines, including psychology. It is an opportunity to re-envision what it means to be intelligent in a diverse global context while also honoring and recognizing the value of difference, positionality, and other ways of knowing.

Effects of comorbidity on executive functions among children with ADHD, finding trends

There is still no basic overview about the effect of various types of comorbidity in executive functions due to two main reasons: (1) the type and number of comorbidities in ADHD is significantly varied, (2) EFs are very diverse and have different neuropsychological properties. Our objective was to determine the effect of comorbid disorders (number and type) on the performance in a wide range (seven) of executive functions in a sample of children with ADHD. Fifty-five male children aged seven to nine years with ADHD were divided into six groups: G1 = ADHD only (ADHD-O), G1 = Oppositional defiant disorder (ODD), G3 = (anxiety/depressive disorder (ADD), G4 = ODD + ADD, G5 = ODD + learning disorder (LD), G6 = ODD + LD + conduct disorder (CD). The six groups exhibited different number of deficits in EFs; G1 showed only 1 deficit in contrast, G6 presented 11. Statistical analysis (ANOVA and logistic regression) identified three most affected EFs: Working memory, generation/classification of semantic categories, and inhibitory control. Alterations in EFs increased mainly in relation to the increase of the specific number and type of comorbidity. To date, no studies have addressed comorbidity from this perspective. A wide range approach of EF confirms the need to further study comorbidity in ADHD from a wide range/variety perspective and determine all possible combinations (number/type) to clarify its contribution to the complex neuropsychology functioning in ADHD.

For better or for worse? Memories and mental health related to COVID-19 lockdowns in adolescents with Attention Deficit Disorders

PURPOSE

In adolescents with Attention Deficit Hyperactivity Disorders (ADHD, ICD-10 defined) we examined self-reported well-being, depressive symptoms and autobiographical memories from the first COVID-19 lockdown in Denmark in comparison to adolescents without an ADHD diagnosis.

METHODS

Data from 16 adolescents with ADHD and 16 non-ADHD age and gender matched controls were collected between September 2020 and April 2021. Questionnaires included the World Health Organization Well-Being Index (WHO-5), the Short Mood and Feelings Questionnaire (SMFQ), and an autobiographical memory survey assessing a lockdown memory, a memory not related to lockdown and a future projection. Mixed design ANOVAs were used to compare within subject differences in memory types across groups and independent sample t-tests were used to compare group differences.

RESULTS

Three adolescents with ADHD scored below the WHO-5 cut-off (< 50) and above the SMFQ cut-off (> 8) indicating risk of depression, compared to two in the control group. Both groups rated lockdown memories as less positive and more negative and reported feeling more sad and worried when reminiscing about lockdown experiences compared to 'other personal memories' and 'future projections'. Compared to the non-ADHD controls, adolescents with ADHD reported more sadness, t(30) = -0.2.45, p < .05 and worries t(30) = -3.84, p < .001 when reminiscing about the lockdown.

CONCLUSIONS

Even though there were no striking differences between groups in the assessments on risk of depression, the findings suggest that adolescents diagnosed with ADHD were more negatively affected when recalling memories about the lockdown compared to their peers.

Working and short-term memory in children with ADHD: an examination of prefrontal cortical functioning using functional Near-Infrared Spectroscopy (fNIRS)

Working memory impairments are an oft-reported deficit among children with ADHD, and complementary neuroimaging studies implicate reductions in prefrontal cortex (PFC) structure and function as a neurobiological explanation. Most imaging studies, however, rely on costly, movement-intolerant, and/or invasive methods to examine cortical differences. This is the first study to use a newer neuroimaging tool that overcomes these limitations, functional Near Infrared Spectroscopy (fNIRS), to investigate hypothesized prefrontal differences. Children (aged 8-12) with ADHD (N = 22) and typically developing (N = 18) children completed phonological working memory (PHWM) and short-term memory (PHSTM) tasks. Children with ADHD evinced poorer performance on both tasks, with greater differences observed in PHWM (Hedges' g = 0.67) relative to PHSTM (g = 0.39). fNIRS revealed reduced hemodynamic response among children with ADHD in the dorsolateral PFC while completing the PHWM task, but not within the anterior or posterior PFC. No between-group fNIRS differences were observed during the PHSTM task. Findings suggest that children with ADHD exhibit an inadequate hemodynamic response in a region of the brain that underlies PHWM abilities. The study also highlights the use of fNIRS as a cost-effective, noninvasive neuroimaging technique to localize/quantify neural activation patterns associated with executive functions.

Memory deficits and hippocampal cytokine expression in a rat model of ADHD

Attention-deficit/hyperactivity disorder (ADHD) is a complex behavioral disorder characterized by hyperactivity, impulsivity, inattention, and deficits in working memory and time perception. While animal models have advanced our neurobiological understanding of this condition, there are limited and inconsistent data on working and elapsed time memory function. Inflammatory signaling has been identified as a key factor in memory and cognitive impairments, but its role in ADHD remains unclear. Additionally, the disproportionate investigation of male subjects in ADHD research has contributed to a poor understanding of the disorder in females. This study sought to investigate the potential connections between memory, neuroimmunology, and ADHD in both male and female animals. Specifically, we utilized the spontaneously hypertensive rat (SHR), one of the most extensively studied animal models of ADHD. Compared to their control, the Wistar-Kyoto (WKY) rat, male SHR are reported to exhibit several behavioral phenotypes associated with ADHD, including hyperactivity, impulsivity, and poor sustained attention, along with impairments in learning and memory. As the hippocampus is a key brain region for learning and memory, we examined the behavior of male and female SHR and WKY rats in two hippocampal-dependent memory tasks. Our findings revealed that SHR have delay-dependent working memory deficits that were similar to, albeit less severe than, those seen in hippocampal-lesioned rats. We also observed impairments in elapsed time processing in female SHR, particularly in the discrimination of longer time durations. To investigate the impact of inflammatory signaling on memory in these rats, we analyzed the levels of several cytokines in the dorsal and ventral hippocampus of SHR and WKY. Although we found some sex and genotype differences, concentrations were generally similar between groups. Taken together, our results indicate that SHR exhibit deficits in spatial working memory and memory for elapsed time, as well as some differences in hippocampal cytokine concentrations. These findings contribute to a better understanding of the neurobiological basis of ADHD in both sexes and may inform future research aimed at developing effective treatments for the disorder. Nonetheless, the potential mediating role of neuroinflammation in the memory symptomatology of SHR requires further investigation.

Measuring children's sustained selective attention and working memory: validity of new minimally linguistic tasks

This study introduces visual tasks using nonlinguistic stimuli that measure sustained selective attention (SSA) and working memory (WM), two constructs foundational to learning and associated with developmental disorders in children. Using an argument-based approach to validation, we examine whether each task (a) measures distinct constructs, (b) shows internal consistency, (c) captures a range of performance, and (d) relates to development as indexed by age. Participants included 71 children, ages 4-10, of whom 12 had parental concern for language/learning. The SSA task presented spatial locations within a long and uninteresting task, following the continuous performance task paradigm. The WM task presented paired location sequences of increasing length, incorporating key elements of the n-back and complex span paradigms. Controlling for age, tasks were found to be minimally associated with each other (r = .26), suggesting related but distinct constructs. Internal consistency was high, with split-half reliability of .94 (SSA) and .92 (WM); the stability of these estimates was supported by bootstrapping simulations. Task performance was evenly distributed, with minimal floor or ceiling effects within this age range. Performance was positively related to age (SSA r = .49; WM r = .53). Exploratory correlations with a measure of parental concern were significant for SSA but not WM. The results show that these new tasks can be used to measure children's SSA and WM in a visual domain with minimal linguistic influence. These tasks capture developmental changes in the early school years. Further investigation can examine their utility for classifying children with developmental disorders.

Executive functions underlie word reading and reading fluency in Chinese children with attention deficit/hyperactivity disorder, reading disabilities, and comorbid attention deficit/hyperactivity disorder and reading disabilities

The current study examined the executive function (EF) deficits and their roles in reading in one hundred and four Cantonese-speaking children with typical development, reading disabilities (RD), ADHD, and comorbid ADHD and RD (ADHD + RD). Children's EF and reading skills were measured. Analysis of variance results showed that all children with disorders manifested deficits in verbal and visuospatial short-term and working memory and behavioral inhibition. Moreover, children with ADHD and ADHD + RD also exhibited deficits in inhibition (IC and BI) and cognitive flexibility. These findings demonstrated that the EF deficits in Chinese children with RD, ADHD, and ADHD + RD are similar to those in their counterparts using alphabetic languages. However, children with ADHD + RD displayed more severe deficits in visuospatial working memory compared to children with RD and ADHD, which was inconsistent with that observed in children using alphabetic languages. Regression analysis results showed that verbal short-term memory was a significant predictor for both word reading and reading fluency in children with RD and ADHD + RD. Moreover, behavioral inhibition significantly predicted reading fluency in children with ADHD. These findings also agreed with previous studies. Collectively, the results of the current study showed that the EF deficits and their roles in reading found in Chinese children with RD, ADHD, and ADHD + RD are mainly consistent with children using alphabetic languages. However, more studies are still needed to confirm these findings, especially comparing the severity of working memory among these three disorders.

Measurement Invariance of the WISC-V across a Clinical Sample of Children and Adolescents with ADHD and a Matched Control Group

Measurement invariance of the Wechsler Intelligence Scale for Children, Fifth Edition (WISC-V) 10-primary subtest battery was analyzed across a group of children and adolescents with ADHD (n = 91) and a control group (n = 91) matched by sex, age, migration background, and parental education or type of school. First, confirmatory factor analyses (CFAs) were performed to establish the model fit for the WISC-V second-order five-factor model in each group. A sufficiently good fit of the model was found for the data in both groups. Subsequently, multigroup confirmatory factor analyses (MGCFAs) were conducted to test for measurement invariance across the ADHD and control group. Results of these analyses indicated configural and metric invariance but did not support full scalar invariance. However, after relaxing equality constraints on the Vocabulary (VC), Digit Span (DS), Coding (CD), Symbol Search (SS), and Picture Span (PS) subtest intercepts as well as on the intercepts of the first-order factors Working Memory (WM) and Processing Speed (PS), partial scalar invariance could be obtained. Furthermore, model-based reliability coefficients indicated that the WISC-V provides a more precise measurement of general intelligence (e.g., represented by the Full-Scale IQ, FSIQ) than it does for cognitive subdomains (e.g., represented by the WISC-V indexes). Group comparisons revealed that the ADHD group scored significantly lower than the control group on four primary subtests, thus achieving significantly lower scores on the corresponding primary indexes and the FSIQ. Given that measurement invariance across the ADHD and the control group could not be fully confirmed for the German WISC-V, clinical interpretations based on the WISC-V primary indexes are limited and should only be made with great caution regarding the cognitive profiles of children and adolescents with ADHD.

Brief Report: A Randomized Controlled Trial of a Digital Working Memory Intervention for Preschoolers Displaying ADHD Symptoms

PURPOSE

This study aimed to investigate the effects of a self-paced digital working memory (WM) intervention on preschoolers with ADHD symptoms and explore the relation between WM and time perception (TP) through a randomized controlled trial.

METHOD

Fifty preschoolers between four-to-six years of age (M = 4.93 years) were randomly assigned to three groups: a WM training group (WM; n = 14), a social-emotional (SE) training active control group (n = 15), and a waitlist control group (n = 21). Both the WM and SE groups received fifteen 10-min self-paced digital training sessions over five consecutive weeks.

RESULTS

The digital WM training was effective in improving children's digit span performance compared to the waitlist control group only. Within-group comparisons across two time points indicated a near-significant improvement in numeration and trends of reduced ADHD symptoms and improved TP tasks in the WM group at the post-test, but between-group differences were not observed.

CONCLUSION

The study showed limited effects of the WM training on preschoolers displaying ADHD symptoms. However, the results implied an association between working memory and time perception that awaits further investigation.

Exploring the steps of learning: computational modeling of initiatory-actions among individuals with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is characterized by difficulty in acting in a goal-directed manner. While most environments require a sequence of actions for goal attainment, ADHD was never studied in the context of value-based sequence learning. Here, we made use of current advancements in hierarchical reinforcement-learning algorithms to track the internal value and choice policy of individuals with ADHD performing a three-stage sequence learning task. Specifically, 54 participants (28 ADHD, 26 controls) completed a value-based reinforcement-learning task that allowed us to estimate internal action values for each trial and stage using computational modeling. We found attenuated sensitivity to action values in ADHD compared to controls, both in choice and reaction-time variability estimates. Remarkably, this was found only for first-stage actions (i.e., initiatory actions), while for actions performed just before outcome delivery the two groups were strikingly indistinguishable. These results suggest a difficulty in following value estimation for initiatory actions in ADHD.

Effects of stochastic vestibular stimulation on cognitive performance in children with ADHD

Previous work has shown that exposure to auditory white noise (WN) can improve cognitive performance in children with ADHD, but it is unknown whether this improvement generalizes to other sensory modalities. To address this knowledge gap, we tested the effect of Stochastic Vestibular Stimulation (SVS) on cognitive performance and reaction time (RT) variability in two groups: children with ADHD and typically developing children (TDC). Children with ADHD (N=42) and TDC (N=28) performed three cognitive tasks (Spanboard, Word Recall and N-back tasks) at two different occasions, with and without exposure to SVS, in a double blinded design. The results showed no main effects of SVS on neither performance nor RT variability for children in any of the groups, and no interactions between SVS and group. Based on these results we conclude that, using our stimulation protocol, the positive effects of WN exposure on cognition in children with ADHD do not generalize to Stochastic Vestibular Stimulation.

Screen time, impulsivity, neuropsychological functions and their relationship to growth in adolescent attention-deficit/hyperactivity disorder symptoms

Previous longitudinal studies found significant associations between screen time and increase in attention-deficit/hyperactivity disorder (ADHD) symptoms, but the mechanisms mediating this association remain understudied. Thus, we used data from a 5-year population-based longitudinal cohort of nearly 4000 Canadian high school students, modeled using multivariate multilevel mediation, to investigate the association of screen time (i.e., social media, television, video games, computer use) with ADHD symptoms via different potential behavioral and neuropsychological mediators (i.e. impulsivity, response inhibition, working memory). We studied direct and indirect between-person, concurrent within-person, and lagged-within-person effects of screens on ADHD symptoms. Results showed that increases in screen time in a given year were associated with an exacerbation of ADHD symptoms within that same year (within-person association), over and above potential common vulnerability (between-person association). Impulsivity proved to be the most robust mediator in the association of screen time with ADHD symptoms at both between and within-person levels. Only social media use displayed a significant lagged-within-person association with ADHD symptoms mediated by impulsivity, indicating an enduring influence on behavior, which was further shown to be mediated by chained changes in response inhibition on a Go/No-Go task. These findings provide clinical implications of screen time and should be an important focus in the management and prevention of ADHD symptoms among adolescents.

Working Memory-Related Neurofunctional Correlates Associated with the Frontal Lobe in Children with Familial vs. Non-Familial Attention Deficit/Hyperactivity Disorder

Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder with high prevalence, heritability, and heterogeneity. Children with a positive family history of ADHD have a heightened risk of ADHD emergence, persistence, and executive function deficits, with the neural mechanisms having been under investigated. The objective of this study was to investigate working memory-related functional brain activation patterns in children with ADHD (with vs. without positive family histories (ADHD-F vs. ADHD-NF)) and matched typically developing children (TDC). Voxel-based and region of interest analyses were conducted on two-back task-based fMRI data of 362 subjects, including 186, 96, and 80 children in groups of TDC, ADHD-NF, and ADHD-F, respectively. Relative to TDC, both ADHD groups had significantly reduced activation in the left inferior frontal gyrus (IFG). And the ADHD-F group demonstrated a significant positive association of left IFG activation with task reaction time, a negative association of the right IFG with ADHD symptomatology, and a negative association of the IFG activation laterality index with the inattention symptom score. These results suggest that working memory-related functional alterations in bilateral IFGs may play distinct roles in ADHD-F, with the functional underdevelopment of the left IFG significantly informing the onset of ADHD symptoms. Our findings have the potential to assist in tailored diagnoses and targeted interventions in children with ADHD-F.

Alterations of neural activity in the prefrontal cortex associated with deficits in working memory performance

Working memory (WM), a core cognitive function, enables the temporary holding and manipulation of information in mind to support ongoing behavior. Neurophysiological recordings conducted in nonhuman primates have revealed neural correlates of this process in a network of higher-order cortical regions, particularly the prefrontal cortex (PFC). Here, we review the circuit mechanisms and functional importance of WM-related activity in these areas. Recent neurophysiological data indicates that the absence of these neural correlates at different stages of WM is accompanied by distinct behavioral deficits, which are characteristic of various disease states/normal aging and which we review here. Finally, we discuss emerging evidence of electrical stimulation ameliorating these WM deficits in both humans and non-human primates. These results are important for a basic understanding of the neural mechanisms supporting WM, as well as for translational efforts to developing therapies capable of enhancing healthy WM ability or restoring WM from dysfunction.

The Relationship Between Speech and Language Disorders and Working Memory: Children with Attention Deficit and Hyperactivity Disorder and Typical Development

OBJECTIVE

To examine the speech, language, and communication skills of school-age children with attention deficit and hyperactive disorder.

METHOD

The sample of the study consists of attention deficit and hyperactivity disorder (n = 47) participants who are combined type and attention-deficit-dominant type, and the control group (n = 40) typically developing participants. Turkish School Age Language Development Test, Turkish Articulation and Phonology Test, Working Memory Scale, and Predictive Cluttering Inventory were applied to all participants.

RESULTS

SPSS program was used in the analysis of the data. Mann Whitney U and One Way ANOVA analyzes were performed to find the difference between the groups. As a result of the statistical analysis, a significant difference was found between the participants with typical development and those with attention deficit and hyperactivity disorder in terms of word count (p < .001). It was determined that participants with typical development outperformed participants with attention deficit and hyperactivity disorder in all tests. There was no difference in the two subtypes of the attention deficit and hyperactivity disorder group (p > .001).

CONCLUSION

It has been concluded that language, speech, and working memory skills of children with attention deficit and hyperactivity disorder are lower than their peers with typical development. Speech and language skills and working memory must be taken into consideration in assessment and intervention children with attention deficit and hyperactivity disorder.

A longitudinal investigation of parental ratings and performance metrics for executive functioning and symptom severity in clinically referred youth with ADHD

There remains a knowledge gap concerning the persistence of attention deficit hyperactivity disorder (ADHD) over the longer term. The current study aimed to investigate the change in parent-rated, and performance-based metrics of executive functioning (EF) and the relationship between these EF metrics and ADHD symptoms in individuals with ADHD from childhood/adolescence to young adulthood. This was done by examining possible improvements in parent-rated EF and performance-based measures of inattention and inhibition over a three-year interval and their relationship to ADHD outcomes in 137 clinically referred youth with ADHD (mean age = 12.4 years, SD = 3.1). Participants' parents completed the Behavior Rating Inventory of Executive Function (BRIEF) and the Swanson-Nolan-Pelham Scale at baseline and follow-up. Participants completed the Conners' Continuous Performance Test, Version II (CPT II) at baseline and follow-up. Statistical analyses were performed with Linear Mixed Models. The sex- and age-standardized measures Commission and Hit reaction time (RT) subscales of the CPT II and parent-rated metacognitive, and behavior regulation composites of the BRIEF were largely stable between measuring points. CPT Omissions, Hit RT standard error (reaction time variability), and parent-rated ADHD symptom scores improved slightly. BRIEF composites and reaction time variability were related to ADHD symptoms using longitudinal data. Overall, behavioral aspects of EF, as observed by parents in the home context, appear to play a significant role in the trajectory of childhood ADHD.

Single-dose effects of methylphenidate and atomoxetine on functional connectivity during an n-back task in boys with ADHD

RATIONALE

Working memory deficits and associated neurofunctional abnormalities are frequently reported in attention-deficit/hyperactivity disorder (ADHD). Methylphenidate and atomoxetine improve working memory performance and increase activation of regions under-functioning in ADHD. Additionally, methylphenidate has been observed to modulate functional networks involved in working memory. No research, however, has examined the effects of atomoxetine or compared the two drugs.

OBJECTIVES

This study aimed to test methylphenidate and atomoxetine effects on functional connectivity during working memory in boys with ADHD.

METHODS

We tested comparative effects of methylphenidate and atomoxetine on functional connectivity during the n-back task in 19 medication-naïve boys with ADHD (10-15 years old) relative to placebo and assessed potential normalisation effects of brain dysfunctions under placebo relative to 20 age-matched neurotypical boys. Patients were scanned in a randomised, double-blind, cross-over design under single doses of methylphenidate, atomoxetine, and placebo. Controls were scanned once, unmedicated.

RESULTS

Patients under placebo showed abnormally increased connectivity between right superior parietal gyrus (rSPG) and left central operculum/insula. This hyperconnectivity was not observed when patients were under methylphenidate or atomoxetine. Furthermore, under methylphenidate, patients showed increased connectivity relative to controls between right middle frontal gyrus (rMFG) and cingulo-temporo-parietal and striato-thalamic regions, and between rSPG and cingulo-parietal areas. Interrogating these networks within patients revealed increased connectivity between both rMFG and rSPG and right supramarginal gyrus under methylphenidate relative to placebo. Nonetheless, no differences across drug conditions were observed within patients at whole brain level. No drug effects on performance were observed.

CONCLUSIONS

This study shows shared modulating effects of methylphenidate and atomoxetine on parieto-insular connectivity but exclusive effects of methylphenidate on connectivity increases in fronto-temporo-parietal and fronto-striato-thalamic networks in ADHD.

Attention Deficit-Hyperactivity Disorder (ADHD): From Abnormal Behavior to Impairment in Synaptic Plasticity

Attention deficit-hyperactivity disorder (ADHD) is a neurodevelopmental disorder with high incidence in children and adolescents characterized by motor hyperactivity, impulsivity, and inattention. Magnetic resonance imaging (MRI) has revealed that neuroanatomical abnormalities such as the volume reduction in the neocortex and hippocampus are shared by several neuropsychiatric diseases such as schizophrenia, autism spectrum disorder and ADHD. Furthermore, the abnormal development and postnatal pruning of dendritic spines of neocortical neurons in schizophrenia, autism spectrum disorder and intellectual disability are well documented. Dendritic spines are dynamic structures exhibiting Hebbian and homeostatic plasticity that triggers intracellular cascades involving glutamate receptors, calcium influx and remodeling of the F-actin network. The long-term potentiation (LTP)-induced insertion of postsynaptic glutamate receptors is associated with the enlargement of spine heads and long-term depression (LTD) with spine shrinkage. Using a murine model of ADHD, a delay in dendritic spines' maturation in CA1 hippocampal neurons correlated with impaired working memory and hippocampal LTP has recently reported. The aim of this review is to summarize recent evidence that has emerged from studies focused on the neuroanatomical and genetic features found in ADHD patients as well as reports from animal models describing the molecular structure and remodeling of dendritic spines.

Community Participation, Supports and Barriers of Adolescents with and without Attention Deficit Hyperactivity Disorder

AIM

To compare participation patterns, environmental supports, and barriers to community activities in adolescents with and without attention deficit hyperactivity disorder (ADHD) in Turkey.

METHODS

Participants were 94 adolescents with ADHD and 109 adolescents without ADHD ages 13-17 years (mean age 14.6, S.D 1.49 years) Participation frequency, involvement rate, mothers who desired change, and environmental supports and barriers in a community setting were assessed with the Participation and Environment Measure for Children and Youth (PEM-CY).

RESULTS

Adolescents with ADHD participated 20.3% less frequently in socializing with peers in the community than adolescents without ADHD. With moderate to large effect sizes, the mean involvement rate in four community activities, including neighborhood outings, community events, socializing with peers in the community, and religious activities, was significantly lower for adolescents with ADHD than for adolescents without ADHD.

CONCLUSION

Adolescents with ADHD participate less frequently and are less involved in socializing with peers in the community. Almost half of all ADHD adolescents never participate in community events. It was seen that cognitive difficulties, sensory qualities, and safety may prevent adolescents with ADHD from socializing with peers in the community.

Psycholinguistic profiling of children with sluggish cognitive tempo

Language disorders are frequently comorbid with attention deficit/hyperactivity disorder (ADHD). Sluggish cognitive tempo (SCT), a second attention disorder, may potentially explain some of the links between language disorders and ADHD. In this study we examined the psycholinguistic abilities of 207 children (mean age 7;10) with and without clinically significant levels of SCT symptoms to determine the degree to which symptoms of language disorder co-occur in cases of SCT. Analyses of children's tense-marking, nonword repetition, and sentence recall indicated that deficits in these areas were not associated with SCT. Instead, SCT appears to be more closely aligned with features of social (pragmatic) communication disorder.

Fronto-parietal white matter microstructure associated with working memory performance in children with ADHD

INTRODUCTION

Attention Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder with many functional impairments thought to be underpinned by difficulties in executive function domains such as working memory. The superior longitudinal fasciculus (SLF) plays an integral role in the development of working memory in neurotypical children. Neuroimaging research suggests reduced white matter organization of the SLF may contribute to working memory difficulties commonly seen in ADHD. This study aimed to examine the relationship between white matter organization of the SLF and working memory in children with ADHD.

METHODS

We examined the association of tract volume and apparent fibre density (AFD) of the SLF with working memory in children with ADHD (n = 64) and controls (n = 58) aged 9-11years. Children completed a computerized spatial n-back task and underwent diffusion magnetic resonance imaging (dMRI). Constrained spherical deconvolution-based tractography was used to construct the three branches of the SLF bilaterally and examine volume and AFD of the SLF.

RESULTS

Regression analyses revealed children with ADHD exhibited poorer working memory, and lower volume and AFD of the left SLF-II compared to healthy controls. There was also an association between reaction time and variability (RT and RT-V) and the left SLF-II. Further analyses revealed volume of the left SLF-II mediated the relationship between ADHD and working memory performance (RT and RT-V).

DISCUSSION

These findings add to the current body of ADHD literature, revealing the potential role of frontoparietal white matter in working memory difficulties in ADHD.

Ocular and neural genes jointly regulate the visuospatial working memory in ADHD children

OBJECTIVE

Working memory (WM) deficits have frequently been linked to attention deficit hyperactivity disorder (ADHD). Despite previous studies suggested its high heritability, its genetic basis, especially in ADHD, remains unclear. The current study aimed to comprehensively explore the genetic basis of visual-spatial working memory (VSWM) in ADHD using wide-ranging genetic analyses.

METHODS

The current study recruited a cohort consisted of 802 ADHD individuals, all met DSM-IV ADHD diagnostic criteria. VSWM was assessed by Rey-Osterrieth complex figure test (RCFT), which is a widely used psychological test include four memory indexes: detail delayed (DD), structure delayed (SD), structure immediate (SI), detail immediate (DI). Genetic analyses were conducted at the single nucleotide polymorphism (SNP), gene, pathway, polygenic and protein network levels. Polygenic Risk Scores (PRS) were based on summary statistics of various psychiatric disorders, including ADHD, autism spectrum disorder (ASD), major depressive disorder (MDD), schizophrenia (SCZ), obsessive compulsive disorders (OCD), and substance use disorder (SUD).

RESULTS

Analyses at the single-marker level did not yield significant results (5E-08). However, the potential signals with P values less than E-05 and their mapped genes suggested the regulation of VSWM involved both ocular and neural system related genes, moreover, ADHD-related genes were also involved. The gene-based analysis found RAB11FIP1, whose encoded protein modulates several neurodevelopment processes and visual system, as significantly associated with DD scores (P = 1.96E-06, Padj = 0.036). Candidate pathway enrichment analyses (N = 53) found that forebrain neuron fate commitment significantly enriched in DD (P = 4.78E-04, Padj = 0.025), and dopamine transport enriched in SD (P = 5.90E-04, Padj = 0.031). We also observed a significant negative relationship between DD scores and ADHD PRS scores (P = 0.0025, Empirical P = 0.048).

CONCLUSIONS

Our results emphasized the joint contribution of ocular and neural genes in regulating VSWM. The study reveals a shared genetic basis between ADHD and VSWM, with GWAS indicating the involvement of ADHD-related genes in VSWM. Additionally, the PRS analysis identifies a significant relationship between ADHD-PRS and DD scores. Overall, our findings shed light on the genetic basis of VSWM deficits in ADHD, and may have important implications for future research and clinical practice.

Mechanisms of Cognitive Change: Training Improves the Quality But Not the Quantity of Visual Working Memory Representations

As of yet, visual working memory (WM) training has failed to yield consistent cognitive benefits to performance in untrained tasks, despite large improvements in trained tasks. Investigating the mechanisms underlying training effects can help explain these inconsistencies. In this pre-registered, pre-test/post-test online training study, we examined how training affects the quantity and quality of representations in visual WM using continuous-reproduction tasks. N = 64 young healthy adults were randomly assigned to an experimental group or an active control group to complete four training sessions of practce in an orientation-reproduction or a visual search task, respectively. We observed that, in the trained task, only the quality, but not the quantity, of visual WM representations significantly increased in the experimental group relative to the control group. These improvements did not generalise to untrained stimuli or paradigms. Therefore, our findings suggest that training gains are not driven by enhanced capacity. Instead, gains in the quality of visual WM representations that are tied to specific stimuli and paradigms may reflect enhanced efficiency in using the existing visual WM capacity.

Comparison of transcranial brain stimulation approaches: prefrontal theta alternating current stimulation enhances working memory performance

Introduction

One of the most important cognitive functions in our everyday life is the working memory (WM). In several neuropsychiatric diseases such as ADHD or schizophrenia WM deficits can be observed, making it an attractive target for non-invasive brain stimulation methods like transcranial electrical stimulation (tES). However, the literature shows rather heterogeneous results of tES effects on WM performance. fMRI meta-analyses have identified a WM network including frontoparietal brain areas such as the dorsolateral prefrontal cortex (DLPFC) and the posterior parietal cortex (PPC). Neurophysiological studies revealed oscillatory activity in the theta band frequency range to be of crucial functional relevance for WM processes. Based on this, transcranial alternating current stimulation (tACS) in the theta frequency range targeting DLPFC and PPC in a spatially optimized way might further improve effects of tES on WM performance.

Methods

Sixteen healthy subjects were stimulated with varying stimulation settings on four different days in a counterbalanced within-subject design. These setups included the application of (1) tACS with a frequency of 5 Hz (theta frequency range) over the left DLPFC and (2) the right superior parietal cortex, (3) transcranial direct current stimulation (tDCS) of the DLPFC and (4) a sham stimulation condition during the online performance of a visual delayed-match-to-sample task with varying working memory load. We introduce a procedure to calculate an optimal tES model revealing optimized high-density setups for the present study for 3 cathodes and 1 anode and stimulation currents of 1.5 mA.

Results

A significant interaction effect of stimulation type and load condition on working memory capacity was found. This was reflected by a significant improvement of WM performance in the high load condition during tACS over the left DLPFC compared with sham stimulation, which was not the case for our parietal tACS or tDCS setup.

Discussion

Working memory performance can be improved with optimized high-definition tACS with a frequency of 5 Hz over the left DLPFC. The conception of different mechanisms underlying transcranial electrical stimulation with alternating and direct currents is supported by these results. Patients suffering from working memory impairments due to neuropsychiatric diseases might potentially benefit from this brain stimulation approach.

Developmental trajectory of hot and cold executive functions in children with and without attention deficit-hyperactivity disorder (ADHD)

BACKGROUND

Children with attention deficit hyperactivity disorder (ADHD) have a delayed development. Two main cognitive models of ADHD are executive (cold) and motivational (hot) models. In this study, we aimed to compare the development of hot and cold executive functions in children with and without ADHD.

METHODS AND PROCEDURES

Forty-six children with ADHD symptoms (56% boys) and forty-four typically developing controls (54% boys), in three age groups of 6-8, 8-10 and 10-12 years, were participated in the study. Go/No-Go Task (GNGT), One-Back Test (OBT) and Shifting Attention Test (SAT), Delay Discounting Test (DDT) and Balloon Analogue Risk Task (BART) were used for assessment.

OUTCOMES AND RESULTS

Children with ADHD showed lower performance in GNG, OBT, SAT, and BART, but intact performance in DDT. The tasks' performance was significantly different between three age groups in GNG and SAT, but similar in OBT and BART. The interaction effect was significant only for the BART measures.

CONCLUSIONS AND IMPLICATIONS

Children with ADHD compared to typically developing children, experience impaired hot and cold executive functions. The cognitive delay was found only in risky decision making as a hot executive function.

Latent structure of working memory and emotion regulation in pediatric ADHD

Working memory is a key cognitive function that is often implicated in ADHD and may represent an underlying cognitive endophenotype of the disorder. Working memory is related to emotion regulation, which is a common area of impairment in children with ADHD. Given the high rate of comorbid diagnoses with ADHD, children with comorbid internalizing, externalizing, and developmental disorders may present with variable working memory profiles and subsequent emotion regulation deficits. This study aimed to adequately characterize the latent structure of working memory impairments and emotional regulation outcomes in a clinical sample of children ages 6-16 with ADHD. This study also examined the interplay between the identified working memory/emotion regulation patterns, demographic characteristics, and the role of comorbid diagnoses. Results highlighted two distinct, invariant, unrestricted classes of working memory/emotion regulation. Class 1 (Average; 62% of the sample) had significantly lower digit-span scores, and generally persevered emotion regulation functioning per parent/teacher report. Class 2 (Emotionally Dysregulated) had average working memory scores, and elevated emotion regulation problems. The working memory indicators had small correlations with parents (and not teacher) measures of emotion regulation. Finally, latent class membership did not differ by comorbid diagnosis, age, gender, or verbal IQ. Findings elucidate heterogeneity in common domains affected by ADHD and suggest that this heterogeneity may not be due to demographic/comorbidity factors. The role of varying information reports is discussed, and potential assessment and treatment implications are highlighted.

Precision behavioral phenotyping as a strategy for uncovering the biological correlates of psychopathology

Our capacity to measure diverse aspects of human biology has developed rapidly in the past decades, but the rate at which these techniques have generated insights into the biological correlates of psychopathology has lagged far behind. The slow progress is partly due to the poor sensitivity, specificity and replicability of many findings in the literature, which have in turn been attributed to small effect sizes, small sample sizes and inadequate statistical power. A commonly proposed solution is to focus on large, consortia-sized samples. Yet it is abundantly clear that increasing sample sizes will have a limited impact unless a more fundamental issue is addressed: the precision with which target behavioral phenotypes are measured. Here, we discuss challenges, outline several ways forward and provide worked examples to demonstrate key problems and potential solutions. A precision phenotyping approach can enhance the discovery and replicability of associations between biology and psychopathology.

The Effects of Four Compounds That Act on the Dopaminergic and Serotonergic Systems on Working Memory in Animal Studies; A Literature Review

The dopaminergic and serotonergic systems are two of the most important neuronal pathways in the human brain. Almost all psychotropic medications impact at least one neurotransmitter system. As a result, investigating how they affect memory could yield valuable insights into potential therapeutic applications or unanticipated side effects. The aim of this literature review was to collect literature data from animal studies regarding the effects on memory of four drugs known to act on the serotonergic and dopaminergic systems. The studies included in this review were identified in the PubMed database using selection criteria from the PRISMA protocol. We analyzed 29 articles investigating one of four different dopaminergic or serotonergic compounds. Studies conducted on bromocriptine have shown that stimulating D2 receptors may enhance working memory in rodents, whereas inhibiting these receptors could have the opposite effect, reducing working memory performance. The effects of serotonin on working memory are not clearly established as studies on fluoxetine and ketanserin have yielded conflicting results. Further studies with better-designed methodologies are necessary to explore the impact of compounds that affect both the dopaminergic and serotonergic systems on working memory.

Relationship Between Inhibitory Control and Arithmetic in Elementary School Children With ADHD: The Mediating Role of Working Memory

OBJECTIVES

To test if inhibitory control was a significant predictor for arithmetic in children with ADHD and if the relationship between inhibitory control and arithmetic was mediated by working memory.

METHODS

Eighty-four children (ADHD, n = 54; Non-ADHD, n = 30) were tested on their interference control, behavioral inhibition, working memory, and arithmetic. Regression analysis was used to test the predictive role of inhibitory control in arithmetic. Moreover, mediation analysis was done to test whether working memory mediated the relationship between inhibitory control and arithmetic memory.

RESULTS

Interference control but not behavioral inhibition was a significant predictor for arithmetic. In addition, interference control had direct and indirect effects via working memory on arithmetic.

CONCLUSIONS

Results demonstrated that inhibitory control contributed to arithmetic in children with ADHD. Furthermore, interference control had direct and indirect effects via working memory on arithmetic, suggesting interventions for arithmetic difficulties should involve training on both inhibition and working memory.

Computerized working memory training for adults with ADHD in a psychiatric outpatient context-a feasibility trial

This study investigated the feasibility (treatment completion, and acceptability) and preliminary effectiveness of computerized working memory (WM) training in a psychiatric outpatient context for adults with ADHD. Self-ratings, neuropsychological tests, and clinician's assessments were performed pre- and post-Cogmed WM training, as well as at the 2-month follow-up, which included 24 (age M = 36.75 SD = 8.37) participants. Of the 24 participants, 16 (66.67%) completed the 25 sessions within 7 weeks. Completers reported high treatment credibility, but a few spontaneously reported feeling stressed because of the time-consuming nature of the WM training (n = 4). Preliminary effectiveness analyses indicate fewer cognitive difficulties and increased neuropsychological performance in non-trained tests that remained stable at follow-up. Future development of WM training paradigms could investigate ways of making the perception of training experience less demanding regarding being time-consuming. The indication of preliminary effectiveness merits further randomized controlled studies in a clinical context.

Working memory training in children with developmental language disorder: Effects on complex syntax in narratives

This study assesses the impact of a working memory training program on the syntactic complexity of the spontaneous speech of French-speaking children with Developmental Language Disorder (DLD). Thirty-nine 6- to 12-year-old children with DLD were allocated to a WM training (DLD^MM, N = 20) or an active control group (DLD^SQULA, N = 19). The computerized training sessions took place three times a week, yielding 12 training hours per participant. Syntactic complexity was assessed in storytelling, measuring mean length of utterances, use of embedded clauses and rate of errors in complex utterances. The performance of participants with DLD was first compared to previous spontaneous data of 40 typically-developing (TD) children of the same age. Then, intragroup (pre- vs. post-test) and intergroup (DLD^MM vs. DLD^SQULA) comparisons were made to assess the impact of the working memory training on the language measures. Global results confirmed syntactic impairment in children with DLD, as opposed to TD children, with large differences for the use of embedded clauses. Findings also suggested gains in the mastery of embedded clauses in children who participated in the WM training, whereas no gains were observed in the DLD control group. These findings confirm deficits in complex syntax in children with DLD, in particular in embedded clauses, and may encourage the clinical use of language sample analysis, which provides an ecological account of children's language performance. While our results should be replicated on a larger scale, they also suggest positive transfer effects of working memory training on the capacity of participants with DLD to produce embedded clauses, in line with previous studies showing a positive effect of WM training on tasks of expressive syntax. It thus seems that working memory training can yield benefits for language, which leaves open the door to new therapeutic approaches for children with DLD.

The contribution of visual and linguistic cues to the production of passives in ADHD and DLD: evidence from thematic priming

This study investigated how thematic priming via visual and linguistic cues influences the choice of syntactic voice in healthy French-speaking adults and in French-speaking children with typical and atypical development. In particular, we focused on children with attention deficit hyperactivity disorder (ADHD) and developmental language disorder (DLD), two clinical groups with documented syntactic difficulties. Twenty adults (M= 24;7) and 60 children aged 6-11 (20 typically developing, 20 with DLD and 20 with ADHD) were presented with agent or patient cues that progressively increased in strength over three conditions: a no cue condition, a visual cue condition with two cue types (perceptual vs. referential) and a linguistic cue condition with two cue types (topicalization of the agent/patient with and without subsequent sentence initiation). Results showed that all participants produced more passives after having been presented with a patient cue, regardless of cue type (cue > no cue), but linguistic cues facilitated the production of passives significantly more than visual cues (linguistic cue > visual cue). We also found that children with DLD were more sensitive than children with ADHD to visual cues (DLD > ADHD), which were more implicit than the linguistic cues and may have required more attentional resources. The opposite pattern (ADHD > DLD) was true for the linguistic cues, which required syntactic processing. These findings highlight how the development of dynamic tools using cue modality and cue sensitivity might be useful for discriminating children with and without syntactic impairment.

The translational genetics of ADHD and related phenotypes in model organisms

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent neurodevelopmental disorder resulting from the interaction between genetic and environmental risk factors. It is well known that ADHD co-occurs frequently with other psychiatric disorders due, in part, to shared genetics factors. Although many studies have contributed to delineate the genetic landscape of psychiatric disorders, their specific molecular underpinnings are still not fully understood. The use of animal models can help us to understand the role of specific genes and environmental stimuli-induced epigenetic modifications in the pathogenesis of ADHD and its comorbidities. The aim of this review is to provide an overview on the functional work performed in rodents, zebrafish and fruit fly and highlight the generated insights into the biology of ADHD, with a special focus on genetics and epigenetics. We also describe the behavioral tests that are available to study ADHD-relevant phenotypes and comorbid traits in these models. Furthermore, we have searched for new models to study ADHD and its comorbidities, which can be useful to test potential pharmacological treatments.

Can children and adolescents with ADHD use attention to maintain verbal information in working memory?

Children and adolescents with attentional-deficit/hyperactivity disorder (ADHD) present deficits in working memory (WM), but accounts for this phenomenon are still lacking. In this study, we used two variations of a complex-span task to test whether a specific WM mechanism, attentional refreshing, causes these deficits. Attentional refreshing is a maintenance strategy based on the sequential switch of attention between maintaining and processing information in WM. Its use is evidenced by a decrease in recall performance proportional to the distraction of attention away from the memoranda. In this study, we designed two experiments requiring children and adolescents with ADHD symptoms to maintain sequences of letters for subsequent recall, while performing a distracting task. In Experiment 1, the distracting task consisted of reading digits aloud. In Experiment 2, it consisted in making spatial judgements. The pace of the distracting tasks was varied to manipulate the level of attentional distraction. We observed that recall in ADHD participants was higher in the distracting conditions that give attention more opportunity to refresh letters. Moreover, ADHD participants had a similar recall performance to their age-matched typically developing peers. This study shows first evidence that individuals with ADHD can use attention to maintain verbal information in WM and calls for more research to understand their WM development.

A Randomized Trial of a Swimming-Based Alternative Treatment for Children with Attention Deficit Hyperactivity Disorder

Attention deficit hyperactivity disorder (ADHD) is considered a highly prevalent neurodevelopmental childhood disorder extending from ages 1−2 to 12−13, associated with impairment across multiple domains, including social, emotional, and cognitive functioning. Little is known about alternative treatments for this disorder. Interest has grown in physical activity as a potential intervention for rehabilitating children with ADHD. This study aimed to investigate the impact of adapted swimming activity on cognitive functions, academic performance, and related behavior of Tunisian children with ADHD. The study was conducted on school children aged 9 to 12 years (n = 40, 5 female and 35 male) diagnosed with ADHD. They were randomly assigned to an experimental group (exercise intervention) or the control group. The Hayling test was used to assess cognitive performance, the Children Behavior Check List (CBCL) was used to assess ADHD-related behavior, and the change in reading and numeracy proficiency was assessed pre- and post-intervention. After 12 weeks of the intervention, the results revealed that there were significant improvements in behavior (p < 0.001), inhibition process (p < 0.001), and academic performance (p < 0.001) in the experimental group compared with the control group. These findings suggest that adapted swimming activity may have positive implications for cognitive function, behavior, and academic performance. This research may provide preliminary support for alternative therapeutic interventions that could be used by practitioners. Moreover, the results support active practice of recreational physical activities as a strategy to support children in overcoming ADHD deficiencies.

Individual differences in working memory capacity and conscious processing do not explain explicit and implicit learning outcomes in physical education

This study examined the effects of explicit versus implicit learning methods on motor learning and self-efficacy of 11-to 14-year old students (n = 81) practicing the basketball layup during physical education. The main aim was to test the effects of students' verbal working memory capacity (WMC) and propensity for conscious motor processing (CMP) on explicit and implicit learning outcomes. The students practiced basketball layups for three weeks (one session/week) during regular PE classes under practice conditions that either promoted explicit or implicit learning. Verbal WMC and CMP propensity were measured separately. At the posttest, students had significantly improved their layup performance and technique, and self-efficacy, but no differences were noted between the intervention groups (explicit vs. implicit). Students' verbal WMC and CMP propensity did not differentially predict the learning outcomes for the explicit or implicit learning groups. Therefore, in this PE setting, both explicit and implicit learning methods seemed to similarly improve movement skill. Further study is needed to examine under which conditions individual constraints such as verbal WMC and propensity for conscious processing influence the effects of explicit and implicit learning.

Inconsistencies between Subjective Reports of Cognitive Difficulties and Performance on Cognitive Tests are Associated with Elevated Internalising and Externalising Symptoms in Children with Learning-related Problems

Children with learning difficulties are commonly assumed to have underlying cognitive deficits by health and educational professionals. However, not all children referred for psycho-educational assessment will be found to have deficits when their abilities are measured by performance on cognitive tasks. The primary aim of this study was to estimate the prevalence of this inconsistent cognitive profile (ICP) in a transdiagnostic sample of children referred by health and education service providers for problems related to attention, learning and memory (N = 715). A second aim was to explore whether elevated mental health problems were associated with ICPs. Findings suggest that approximately half of this sample could be characterised as having an ICP. Cognitive difficulties, whether identified by parent ratings or task performance, were associated with elevated internalising and externalising difficulties. Crucially, a larger discrepancy between a parent's actual ratings of a child's cognitive difficulties and the ratings that would be predicted based on the child's performance on cognitive tasks was associated greater internalising and externalising difficulties for measures of working memory, and greater externalising difficulties for measures of attention. These findings suggest that subjective cognitive difficulties occurring in the absence of any task-based performance deficits may be a functional problem arising from mental health problems.

Implication of saturated fats in the aetiology of childhood attention deficit/hyperactivity disorder - A narrative review

Attention Deficit/Hyperactivity Disorder (ADHD) is the most common mental health disorder in the paediatric population. ADHD is highly comorbid with obesity, and has also been associated with poor dietary patterns such as increased consumption of refined carbohydrates and saturated fats. Although ADHD in children was associated with high consumption of saturated fats, so far there has been no evidence-based attempt to integrate dietary strategies controlling for intake of saturated fats into the etiological framework of the disorder. Evidence from human studies and animal models has shown that diets high in saturated fats are detrimental for the development of dopaminergic neurocircuitries, synthesis of neurofactors (e.g. brain derived neurotrophic factor) and may promote brain inflammatory processes. Notably, animal models provide evidence that early life consumption of a high saturated fats diet may impair the development of central dopamine pathways. In the present paper, we review the impact of high saturated fats diets on neurobiological processes in human studies and animal models, and how these associations may be relevant to the neuropathophysiology of ADHD in children. The validation of this relationship and its underlying mechanisms through future investigative studies could have implications for the prevention or exacerbation of ADHD symptoms, improve the understanding of the pathogenesis of the disorder, and help design future dietary studies in patients with ADHD.

Road-Crossing Behavior in Complex Traffic Situations: A Comparison of Children With and Without ADHD

All children are vulnerable to pedestrian injuries, but previous research suggests children diagnosed with ADHD may have elevated risk. Child pedestrian injury risk also increases with increasing traffic volume and speed. The current study examined three hypotheses: (a) Pedestrian behavior of children with ADHD is riskier than that of typically-developing children; (b) Children's pedestrian behavior is riskier with increased traffic complexity; and (c) Pedestrian behavior of children with ADHD is influenced more by complex traffic situations than behavior of typically-developing children. A sample of 38 children ages 8-12 years, 45% diagnosed with ADHD, completed 21 virtual street-crossings, 7 in each of three levels of traffic complexity. Outcome measures included unsafe crossings, ratio of looking at traffic by time, start-delay to enter the road, time to contact with oncoming vehicles, and time waiting to cross. A repeated measure MANOVA and follow-up tests showed that all children had more unsafe crossings, shorter start-delays and shorter TTCs when exposed to increased traffic complexity compared to lighter traffic. Children with ADHD had more unsafe crossings than typically-developing children. Further, compared to typically-developing children, ADHD children had comparatively more unsafe crossings, lower time to contact and longer wait-time in more complex traffic environments. Executive function deficits among children with ADHD likely influence their behavior in complex traffic environments. Implications of the results for policy-making and preventive strategies are discussed.