Intraindividual Variability in Attention-Deficit/Hyperactivity Disorder: An Ex-Gaussian Approach.

Higher intraindividual variability (IIV) of response times is consistently noted in children with attention-deficit/hyperactivity disorder (ADHD). The current study investigated whether an ex-Gaussian estimate of IIV in children ages 6-13 years-old could differentiate between children with and without ADHD. Children completed a computerized go/no-go task to estimate trial-by-trial IIV and a continuous performance test (CPT) to estimate inattention and hyperactivity/impulsivity. Parents completed questionnaires assessing inattention and hyperactive/impulsive behaviors. IIV, commission errors, and attention problems as rated by parents were significantly greater in the ADHD group. Groups did not differ on errors of omission, but IIV was predictive of omission errors and parent ratings of inattention and hyperactivity/impulsivity. IIV predicted group membership (ADHD vs Control) whereas errors of omission did not. However, IIV did not improve diagnostic accuracy when parent ratings were used, such that parent ratings were superior at determining diagnosis. Current results support the use of IIV, based on the ex-Gaussian approach, as an objective measure of attention problems over omission errors on sustained attention CPT-type tasks. Additionally, while parent ratings of attention impairment remain the best predictor of ADHD diagnostic status, IIV may be helpful in determining when further assessment is required in the absence of those ratings.

Electrophysiological variability during tests of executive functioning: A comparison of athletes with and without concussion and sedentary control participants.

OBJECTIVE: Sport participation may benefit executive functioning (EF), but EF can also be adversely affected by concussion, which can occur during sport participation. Neural variability is an emerging proxy of brain health that indexes the brain's range of possible responses to incoming stimuli (i.e., dynamic range) and interconnectedness, but has yet to be characterized following concussion among athletes. This study examined whether neural variability was enhanced by athletic participation and attenuated by concussion. METHOD: Seventy-seven participants (18-25 years-old) were classified as sedentary controls (n = 33), athletes with positive concussion history (n = 21), or athletes without concussion (n = 23). Participants completed tests of attention switching, response inhibition, and updating working memory while undergoing electroencephalography recordings to index neural variability. RESULTS: Compared to sedentary controls and athletes without concussion, athletes with concussion exhibited a restricted whole-brain dynamic range of neural variability when completing a test of inhibitory control. There were no group differences observed for either the switching or working memory tasks. CONCLUSIONS: A history of concussion was related to reduced dynamic range of neural activity during a task of response inhibition in young adult athletes. Neural variability may have value for evaluating brain health following concussion.

Feasibility and potential benefits of an attention and executive function intervention on metacognition in a mixed pediatric sample.

The term "metacognition" describes thinking about a cognitive phenomenon or, more simply put, thinking about thinking . Metacognition involves using knowledge about one's cognitive processes to change behavior, including monitoring and controlling cognition. Metacognition is vital for learning and is often more difficult for children with neurodevelopmental concerns (e.g. Attention Deficit Hyperactivity Disorder [ADHD], Fetal Alcohol Spectrum Disorder [FASD], Autism Spectrum Disorders [ASD]), possibly due to underlying deficits in attention and executive functioning (EF). The present study evaluated a 6- to 8-week cognitive intervention aimed at improving attention and EF and children's metacognitive abilities. Participants included a mixed sample of 50 children ages 6-12 years presenting with attention and/or EF deficits. Children within the active intervention group completed a game-based attention/EF intervention called Caribbean Quest (CQ), which combines process-specific and compensatory approaches to remediate attention and EF. Educational Assistants (EAs) supported children during gameplay by teaching explicit metacognitive strategies. Pre/post assessments included measures of attention and working memory (WM), metacognitive awareness (child, parent, and EA questionnaires), and metacognitive regulation (metacognitive monitoring and control). Results indicated post-intervention gains in WM, metacognitive awareness, and metacognitive regulation (self-monitoring and metacognitive control). These results provide preliminary support for CQ as potentially beneficial in improving aspects of EF and metacognition in children.

Intraindividual variability in executive and motor control tasks in children with attention deficit hyperactivity disorder.

OBJECTIVE: Emerging evidence highlights intraindividual variability (IIV) during executive function (EF) tasks as a reliable endophenotype of Attention Deficit/Hyperactivity Disorder (ADHD) and as contributing to motor dysregulation and hyperactive-impulsive behaviors. This study examined the relationship between EF and motor control in children with and without ADHD. METHOD: Ninety-seven children (6-13 years) completed standardized and experimental tasks of executive and motor control. Primary caregivers completed a semi-structured interview, and behavioral rating forms for ADHD symptoms and EF. RESULTS: Children with ADHD demonstrated lower performance on motor dexterity and sequencing tasks, and greater IIV during EF tasks with lower cognitive demand. IIV accounted for ADHD symptoms of hyperactivity, beyond age and motor dexterity. IIV from EF measures with lower cognitive demand was also sensitive to ADHD symptoms. CONCLUSION: IIV metrics may tap into the motor regulation challenges associated with ADHD, as well as attentional lapsing at lower levels of cognitive demand.

Pilot Study of an Attention and Executive Function Cognitive Intervention in Children with Autism Spectrum Disorders.

This pilot study investigated the efficacy of a game-based cognitive training program (Caribbean Quest; CQ) for improving attention and executive function (EF) in school-aged children with Autism Spectrum Disorder (ASD). CQ is a 'serious game' that uses a hybrid process-specific/compensatory approach to remediate attention and EF abilities through repetitive, hierarchically graded exercises delivered in an adaptive format. Game-play is accompanied by instruction in metacognitive strategies delivered by an adult trainer. Twenty children diagnosed with ASD (ages 6-12 years) completed 12 h of intervention in schools over 8-10 weeks that was facilitated by a trained Research Assistant. Pre-post testing indicated near transfer gains for visual working memory and selective attention and far transfer effects for math fluency. Exit interviews with parents and school staff indicated anecdotal gains in attention, EF, emotion-regulation, flexibility, communication, and social skills. Overall, this study provides preliminary support for the feasibility and potential efficacy of the CQ when delivered in schools to children with ASD.

Intraindividual variability in children is related to informant ratings of attention and executive function.

Objective: Attention and executive function (EF) deficits are ubiquitous in neurodevelopmental disorders including Attention Deficit/Hyperactivity Disorder (ADHD), as are high levels of intraindividual variability (IIV). Attention and EF are typically assessed using informant ratings and objective measures; however, discrepancies between different metrics often make it difficult to fully characterize a child's attention capabilities, and IIV has been proposed as a potentially useful discriminator. Our objective was to explore the relationship between IIV, using the residualized intraindividual standard deviation (rISD) method, and informant ratings of attention and EF in a mixed pediatric sample, to determine the potential utility of IIV for aiding attention diagnostics. Another commonly used, though controversial, IIV indicator, the coefficient of variation (ICV), was calculated for comparison purposes. Method: We assessed 51 children with varying degrees of attention and EF deficits. Measures included parent and teacher responses on the Comprehensive Executive Function Inventory (CEFI) and response times (RT) on a go/no-go task, which were used to estimate IIV. Results: Mean RT, rISD, and ICV were significantly related to parent and teacher ratings of attention, though ICV showed a relatively weaker association. rISD also showed associations with parent ratings of working memory and self-monitoring, as well as teacher ratings of working memory. Conclusion: The significant, and relatively stronger, relationship between rISD and parent and teacher ratings of attention supports the use of this metric, compared to mean RT and ICV. The rISD indicator of IIV thus shows potential utility as a unique and objective measure of attention in children across various neurodevelopmental disorders and, with additional research, may prove useful for diagnosis of attention problems.

Evidence of motor-control difficulties in children with attention deficit hyperactivity disorder, explored through a hierarchical motor-systems perspective.

INTRODUCTION: Attention deficit hyperactivity disorder (ADHD) may reflect a disorder of neural systems that regulate motor control. The current study investigates motor dysfunction in children with ADHD using a hierarchical motor-systems perspective where frontal-striatal/"medial" brain systems are viewed as regulating parietal/"lateral" brain systems in a top down manner, to inhibit automatic environmentally driven responses in favor of goal-directed behavior. It was hypothesized that due to frontal-striatal hypoactivation, children with ADHD would have difficulty with higher order motor control tasks felt to be dependent on these systems, yet have preserved general motor function. METHOD: A total of 63 children-ADHD and matched controls-completed experimental motor tasks that required maintenance of internal motor representations and the ability to inhibit visually driven responses. Children also completed a measure of motor inhibition, and a portion of the sample completed general motor function tasks. RESULTS: On motor tasks that required them to maintain internal motor representations and to inhibit automatic motor responses, children with ADHD had significantly greater difficulty than controls, yet on measures of general motor dexterity, their performance was comparable. Children with ADHD displayed significantly greater intraindividual (subject) variability than controls. Intraindividual variability (IIV) contributed to variations in performance across the motor tasks, but did not account for all of the variance on all tasks. CONCLUSIONS: These findings suggest that children with ADHD may be more controlled by external stimuli than by internally represented information, possibly due to dysfunction of the medial motor system. However, it is likely that children with ADHD also display general motor-execution problems (as evidenced by IIV findings), suggesting that atypicalities may extend to both medial and lateral motor systems. Findings are interpreted within the context of contemporary theories regarding motor dysfunction in ADHD, and implications for understanding externalizing behaviors in ADHD are discussed.

Neuropsychological Profiles of Written Expression Learning Disabilities Determined by Concordance-Discordance Model Criteria.

Children with specific learning disabilities (SLD) have disparate neuropsychological processing deficits that interfere with academic achievement in spelling, writing fluency, and/or written expression (WE). Although there are multiple potential causes of WE SLD, there is a paucity of research exploring this critical academic skill from a neuropsychological perspective. This study examined the neuropsychological profiles of WE SLD subtypes defined using the concordance-discordance model (C-DM) of SLD identification. Participants were drawn from a sample of 283 children (194 boys, 89 girls) aged 6 years to 16 years old (M(age) = 9.58 years, SD = 2.29 years) referred for comprehensive neuropsychological evaluations in school settings and subsequently selected based on C-DM determined spelling, writing fluency, and WE SLD. WE SLD subtypes differed on several psychomotor, memory, and executive function measures (F range = 2.48-5.07, p range = .049 to <.001), suggesting that these children exhibit distinct patterns of neuropsychological processing strengths and weaknesses. Findings have relevance for differential diagnosis of WE subtypes, discriminating WE SLD subtypes from low WE achievement, and developing differentiated evidence-based instruction and intervention for children with WE SLD. Limitations and future research will be addressed.

Psychosocial and Adaptive Deficits Associated With Learning Disability Subtypes.

Children with specific learning disabilities (SLD) have deficits in the basic psychological processes that interfere with learning and academic achievement, and for some SLD subtypes, these deficits can also lead to emotional and/or behavior problems. This study examined psychosocial functioning in 123 students, aged 6 to 11, who underwent comprehensive evaluations for learning and/or behavior problems in two Pacific Northwest school districts. Using concordance-discordance model (C-DM) processing strengths and weaknesses SLD identification criteria, results revealed working memory SLD (n = 20), processing speed SLD (n = 30), executive SLD (n = 32), and no disability groups (n = 41). Of the SLD subtypes, repeated measures MANOVA results revealed the processing speed SLD subtype exhibited the greatest psychosocial and adaptive impairment according to teacher behavior ratings. Findings suggest processing speed deficits may be behind the cognitive and psychosocial disturbances found in what has been termed "nonverbal" SLD. Limitations, implications, and future research needs are addressed.