Differences in Executive Functioning in Children with Attention Deficit and Hyperactivity Disorder (ADHD)

Interpreting the direct- and derived-Trail Making Test scores in Argentinian children: regression-based norms, convergent validity, test-retest reliability, and practice effects

Objective: We carried out two research studies (using a cross-sectional and a longitudinal design) to establish regression-based normative data, and to examine the convergent validity, the test-retest reliability, and the changes in performance with practice (1-month and 1-year interval) of the direct- and derived- (B-A, B + A, and B/A ratio) Trail Making Test (TMT) scores in Spanish-speaking children. Method: In S1 (n = 413 6- to 15-year-old children and adolescents), regression-based norming procedure and partial correlations were employed. In S2 (n = 110 6- to 12-year-old children), intraclass correlation coefficient (ICC2,1), Pearson's r-product-moment correlations, and paired t-tests were used. Results: S1 demonstrated that age was associated with better performance on both TMT-A and TMT-B. This improvement was more strongly related to direct scores than derived measures B-A and B/A. Additionally, TMT-B was found to be more related to other executive functions (EF) compared to the performance of TMT-A. Among the derived scores, only the B-A was related primarily to cognitive flexibility, while the B + A index was associated with most EF, suggesting a general measure of cognitive functioning. In S2, fair to good test-retest reliability coefficients were found at Time 2 for TMT-A and TMT-B, as well as the B + A index, both in 6 to 8-year-olds (ICCs .61 to .74) and 9 to 12-year-olds (ICCs .53 to .65). There was a significant increase in performance on TMT-A and TMT-B from the first assessment (Time 1) to the follow-up testing at Time 2 in older children. However, this significant improvement was not observed for TMT-B in the younger group. Test scores on the TMT direct measures improved significantly across 1-year. The B-A and B/A ratio scores did not change across examinations. Conclusions: These findings have important implications for assessing EF and developing interventions that target cognitive flexibility in pediatric populations.

Effects of rope skipping exercise on working memory and cardiorespiratory fitness in children with attention deficit hyperactivity disorder

Introduction

Children with Attention Deficit Hyperactivity Disorder (ADHD) exhibit deficits in working memory (WM) and cardiorespiratory fitness (CRF), both of which are closely associated with the core symptoms of ADHD. This study aimed to investigate the effects of rope skipping exercise (RSE) on the WM and CRF of children with ADHD, to provide a theoretical foundation for the optimization of exercise intervention programs tailored to children with ADHD.

Methods

This study recruited 55 children (age range 6-12 years) and randomly assigned them into three groups: the ADHD with RSE (AWRSE, n=22, mean age: 10.18 ± 1.10 years), the ADHD with sports game (SG) (AWSG, n=16, mean age: 9.38 ± 0.96 years), and the typically developing (TD) control group (CG, n=17, mean age: 8.94 ± 0.56 years). The AWRSE underwent a RSE intervention, while the other two groups participated in SG. The exercise intervention lasted for 8 weeks, with sessions held twice a week for 60 minutes each, at a moderate-to-vigorous-intensity (64-95% HRmax). All children in each group underwent pre-test and post-test, including height, weight, BMI, n-back, and 20mSRT. One-way analysis of variance (Ony-way ANOVA) and paired sample t-test were used to analyze inter- and intra-group differences respectively.

Results

Before the intervention, children with ADHD exhibited a significantly lower VO2max compared to the TD children (p<0.05), and there was no significant difference in the other indicators between the groups (p>0.05). After the intervention, no significant inter-group differences were found across all indices for the three groups of children (p > 0.05). The AWRSE had significant improvements in the accuracy of 1-back task, Pacer (laps), and VO2max (p<0.05), with the level of CRF approaching that of TD children. A significant decrease in response time for the 1-back task was observed in the CG.

Conclusion

An 8-week RSE intervention is an effective therapeutic approach for children with ADHD, significantly enhancing their WM and CRF.

Novel pharmacological targets for GABAergic dysfunction in ADHD

Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopment disorder that affects approximately 5% of the population. The disorder is characterized by impulsivity, hyperactivity, and deficits in attention and cognition, although symptoms vary across patients due to the heterogenous and polygenic nature of the disorder. Stimulant medications are the standard of care treatment for ADHD patients, and their effectiveness has led to the dopaminergic hypothesis of ADHD in which deficits in dopaminergic signaling, especially in cortical brain regions, mechanistically underly ADHD pathophysiology. Despite their effectiveness in many individuals, almost one-third of patients do not respond to stimulant treatments and the long-term negative side effects of these medications remain unclear. Emerging clinical evidence is beginning to highlight an important role of dysregulated excitatory/inhibitory (E/I) balance in ADHD. These deficits in E/I balance are related to functional abnormalities in glutamate and Gamma-Aminobutyric Acid (GABA) signaling in the brain, with increasing emphasis placed on GABAergic interneurons driving specific aspects of ADHD pathophysiology. Recent genome-wide association studies (GWAS) have also highlighted how genes associated with GABA function are mutated in human populations with ADHD, resulting in the generation of several new genetic mouse models of ADHD. This review will discuss how GABAergic dysfunction underlies ADHD pathophysiology, and how specific receptors/proteins related to GABAergic interneuron dysfunction may be pharmacologically targeted to treat ADHD in subpopulations with specific comorbidities and symptom domains. This article is part of the Special Issue on "PFC circuit function in psychiatric disease and relevant models".

Far Transfer Effects of Trainings on Executive Functions in Neurodevelopmental Disorders: A Systematic Review and Metanalysis

Executive Functions are a set of interrelated, top-down processes essential for adaptive goal-directed behaviour, frequently impaired across different neurodevelopmental disorders with variable degrees of severity. Many executive-function-training studies in children with neurodevelopmental disorders have focused on near effects, investigating post-treatment improvements on directly trained processes, while enhancements of skills not directly trained, defined as far effects, are less considered, albeit these could be extremely relevant for reducing the negative impact of a disorder's core symptomatology. This systematic review and metanalysis aims to investigate the far effect outcomes after EF training in children with different types of neurodevelopmental disorders. 17 studies met the inclusion criteria for the systematic review, while 15 studies were selected in the metanalysis. An overall statistically significant effect size was found in the majority of far effect outcome measures considered in the studies. In particular, trainings on executive functions determine significant far effects on daily life functioning (0.46, 95% CI: [0.05-0.87]) and clinical symptoms (0.33, 95% CI: [0.15-0.51]). Despite a high variability of the results, intensity, frequency and the laboratory/life contexts dimension seem to be the most influential variables in determining far effects. This systematic review and metanalysis highlights the need to measure far effects of executive function training in neurodevelopmental disorders, selecting treatments not only on directly targeted processes, but also according to far impacts on the functional weakness of the disorder.

Effects of transcranial direct current stimulation on improving performance of delayed- reinforcement attentional set-shifting tasks in attention-deficit/hyperactivity disorder rat model

Behavioral flexibility (or set-shifting), which is regulated by the prefrontal cortex (PFC), is often impaired in patients with attention-deficit/hyperactivity disorder (ADHD), which is characterized by poor inhibitory control and reinforcement learning. Transcranial direct current stimulation (tDCS) has been proposed as a means of noninvasive brain stimulation and a potential therapeutic tool for modulating behavioral flexibility. Animal studies can pave the way to know if tDCS application can potentially benefit rule- and goal-based activities in ADHD. Spontaneously hypertensive rats (SHRs) and inbred Wistar-Kyoto (WKY) rats were used as an animal model of ADHD and controls, respectively, and their strategy set-shifting abilities, including initial discrimination, set-shifting, and reversal learning tasks under 0-s or 15-s reinforcer delivery delay conditions, were evaluated. The tDCS treatment had a limited effect on the performance of the SHRs and WKY rats in initial discrimination task under 0-s delay condition. Under the 15-s delay condition, the SHRs had longer lever-press reaction times and/or more trial omissions than the WKY rats did when completing set-shifting and reversal-learning tasks. Among the SHRs, tDCS treatment improved the rats' reaction times and/or reduced their trial omissions in the set-shifting and reversal-learning tasks. Although tDCS may improve delayed reinforcement learning set-shifting performance in SHRs, further studies are required to clarify the responsible mechanism.

Enhancing Executive Functions and Handwriting with a Concentrative Coordination Exercise in Children with ADHD: A Randomized Clinical Trial

Handwriting difficulties are common in children with Attention-Deficit/Hyperactivity Disorder (ADHD), and they have been associated with lower academic achievement and self-esteem. Our aim in this study was to determine if training coordination of the head, eyes, and arm and engaging in the necessary visual concentration associated with table tennis would improve executive functions and school-based handwriting among children with ADHD. We designed a randomized controlled trial to explore the therapeutic efficacy of this table tennis training and recruited 48 children with ADHD that we randomly assigned to one of three equal-sized training groups: (a) actual table tennis, (b) simulated table tennis (exergame), or (c) a control group receiving no additional training. The training intervention lasted 12-weeks in which the two different table tennis trainings (i.e., actual or simulated) were scheduled for three one-hour sessions per week. Outcome measures included a computerized handwriting evaluation, the Stroop test, and the Wisconsin Card Sorting Test (WCST). Participants in each table tennis training group showed significant improvements in handwriting performance, response time, and required time to achieve automation. Both intervention groups also showed significant improvements on the Stroop Color-Word test, but only the actual table tennis training group showed a significant improvement on the WCST. This study provided evidence of at least short-term improvements in executive functions and handwriting problems in children with ADHD through their participation in table tennis motor coordination activities.

Relationships between cognition and literacy in children with attention-deficit/hyperactivity disorder: A systematic review and meta-analysis

Evidence suggests that cognitive and literacy difficulties are common for children with Attention-Deficit/Hyperactivity Disorder (ADHD). The current systematic review and meta-analysis investigated the relationship between cognition and literacy in children with ADHD. Ten thousand and thirty-eight articles were screened against the inclusion criteria and six eligible studies were retained for final review. Where two or more studies used comparable measures of cognition and literacy, a meta-analysis of the relationship between these measures was undertaken. A narrative synthesis of all included studies was also completed. There were medium effect sizes between working memory and aspects of reading, and small effect sizes between processing speed and reading. Inhibition and attention had differential relationships with aspects of literacy with varying effect sizes. This systematic review demonstrates differential relationships between aspects of literacy and cognition in children with ADHD. Further examination of these relationships is warranted to support intervention development.

Dimensional structure of the BRIEF2 and its relations with ADHD symptoms and task performance on executive functions in Chinese children

This study examined the dimensional structure of the Behavior Rating Inventory of Executive Function, Second Edition (BRIEF2) in a Chinese sample of children with attention-deficit/hyperactivity disorder (ADHD)-related concerns and the correlations of the BRIEF2 with the children's ADHD symptoms and their performance on executive function (EF) tasks. Participants were 339 Chinese children aged 6-15 (M = 9.18 years, SD = 2.33; boys: 78.2%) recruited from 35 schools in Hong Kong. The results from confirmatory factor analyses revealed the best fit for a three-factor nine-scale model compared to a two-factor or single-factor model. Significant correlations were found between the BRIEF2 parent and teacher forms for the Behavioral Regulation Index and Cognitive Regulation Index, but not for the Emotion Regulation Index. Associations between performance on an EF task and the rating of the corresponding subscale on the BRIEF2 purportedly measuring the same EF construct were not consistently observed. Lastly, the BRIEF2 showed good convergent validity with the ratings of ADHD symptoms on the Swanson, Nolan, and Pelham Rating Scale Version IV (SNAP-IV). This study provided plausibly the first evidence on the dimensional structure of the BRIEF2 Parent and Teacher Forms in an Asian sample and confirmed the factorial validity of the Chinese version of the BRIEF2.

Acute Physical Activity, Executive Function, and Attention Performance in Children with Attention-Deficit Hyperactivity Disorder and Typically Developing Children: An Experimental Study

A growing number of studies support the theory that physical activity can effectively foster the cognitive function of children with attention-deficit hyperactivity disorder (ADHD). The present study examines the effect of acute moderate physical activity on the executive functions and attention performance of (1) typically developing children (without psychological, psychiatric or neurological diagnosis and/or associated treatment stated in their medical history); (2) treatment-naïve ADHD children; and (3) medicated children with ADHD. In the current study, a total sample of 150 (50 non-medicated, 50 medicated, and 50 typically developing) children between the ages of 6 and 12 took part in the experiment. The Mini International Neuropsychiatric Interview for Children and Adolescents (MINI Kid) was used to measure ADHD and the child version of the Test of Attentional Performance (KiTAP) was applied to evaluate the children’s attentional and executive function performance before and after two types of intervention. In order to compare the effects of physical activity and control intervention, half of the children from each group (25 participants) took part in a 20-min long, moderately intense physical activity session on the 60–80% of their maximum heart rate, while watching a cartoon video. In the control condition, the other half of the children (25 participants) from each group watched the same cartoon video for 20 min while seated. Physical activity (compared to the just video watching control condition) had a significantly positive influence on 2 out of 15 measured parameters (median reaction time in the alertness task and error rates in the divided attention task) for the medicated group and on 2 out of the 15 measured variables (number of total errors and errors when distractor was presented, both in the distractibility task) regarding the treatment-naïve group. Future studies should focus on finding the optimal type, intensity, and duration of physical activity that could be a potential complementary intervention in treating deficits regarding ADHD in children.

Spatial Perspective-Taking in Children With Autism Spectrum Disorders: The Predictive Role of Visuospatial and Motor Abilities

Despite its impact on everyday functioning, spatial perspective-taking has rarely been investigated in autism spectrum disorders (ASD), and previous findings are surprisingly sparse and inconsistent. In the present study, we aimed to investigate spatial perspective-taking abilities in children and adolescents with ASD without intellectual disabilities, comparing them with a group of typically developing (TD) peers. Our objectives were: (i) to test similarities and differences between these groups in a spatial perspective-taking task; and (ii) to see whether similar or different underlying processes (i.e., fine and gross motor skills, and visuospatial abilities) might account for the groups’ performance in the spatial perspective-taking task. A group of children with ASD (N = 36) was compared with a TD group (N = 39), aged from 8 to 16 years. Participants were administered tasks assessing spatial perspective-taking, fine and gross motor skills, visuo-constructive abilities, visuospatial working memory, visual imagery, and mental rotation. Our results revealed that the ASD group had more difficulty with the spatial perspective-taking task than the TD group. The two groups also had some shared and some different processes that predicted their perspective-taking performance: a significant predictive effect of fine motor skills and visuospatial working memory emerged for both groups, while gross motor skills (i.e., walking heel-to-toe) and visuospatial imagery only revealed a role in the TD group. These findings suggest that different abilities might account for the two groups’ performance in the spatial perspective-taking task. Gross motor skills and complex visuospatial abilities seem to be more important in sustaining spatial perspective-taking ability in typical development than in the event of ASD. Some of the clinical and educational implications of these findings are discussed.

[Cognitive deficit in children with hyperkinetic disorder]

The review presents current data on the nature of cognitive deficit in children with hyperkinetic disorder, and possible pathophysiological mechanisms of the disease. Considering possible neurobiological components of hyperkinetic disorder, attention is given to pathological functional connections underlying specific clinical manifestations of the disease.

Executive Function and Attention Performance in Children with ADHD: Effects of Medication and Comparison with Typically Developing Children

The emerging literature reports that children with Attention-Deficit/Hyperactivity Disorder (ADHD) show deficits in executive functioning. To date, the combination of drug therapy with certain evidence-based non-medication interventions has been proven to be the most effective treatment for ADHD. There is a gap in the literature regarding comparing the executive functions (EF) of treatment naïve and medicated children with ADHD with both each other and typically developing children. Altogether, 50 treatment naïve and 50 medicated children with ADHD and 50 typically developing children between the ages of six and 12 were enrolled. The Mini International Neuropsychiatric Interview for Children and Adolescents (Mini Kid) and the Test of Attentional Performance for Children (KiTAP) measures were employed. Treatment naïve children with ADHD showed weaker performance on most executive function measures (12 out of 15) than either the medicated ADHD group or the controls. There were no significant differences between the medicated ADHD children and typically developing children in most KiTAP parameters (10 out of 15). Executive function impairments were observable in treatment naïve ADHD children, which draws attention to the importance of treating ADHD. Future studies should focus on the specific effects of stimulant medication on executive functions.