Attention-Deficit/Hyperactivity Disorder Status and Sex Moderate Mild Traumatic Brain Injury Symptom Severity in Children and Adolescents: Implications for Clinical Management.

OBJECTIVE: To investigate the impact of pediatric mild traumatic brain injury (mTBI), using a broad parent-reported measure, and to determine whether parent-ratings of mTBI symptoms are higher among those with premorbid attention-deficit/hyperactivity disorder (ADHD) and females. DESIGN: Retrospective case-control. SETTING: Hospital-based sports medicine clinic. PARTICIPANTS: The retrospective chart review included 1346 (age: M = 13.11 years, SD = 2.6; 61.7% male) pediatric patients with (n = 209) and without (n = 1137) ADHD. INDEPENDENT VARIABLES: Group membership (ADHD vs non-ADHD) and sex (male vs female). MAIN OUTCOME MEASURES: Baseline and current Post-Concussion Symptom Inventory-Parent Report Form (PCSI-P) Physical, Emotional, Cognitive, and Fatigue subscale scores. This study used a retrospective chart review; therefore, the hypotheses reported for the current study were formed after data were collected. RESULTS: Controlling for patient age and days from mTBI, patients with ADHD had significantly higher retrospective parent-reported pre-mTBI ratings of physical, emotional, and cognitive symptoms (ds = 0.17-0.62) and higher post-mTBI ratings across all 4 symptom domains (ds = 0.18-0.57) than those without ADHD. There was no group × time interaction for any of the PCSI-P subscales. Females overall had higher retrospective parent-reported pre-injury Fatigue and Emotional symptoms (ds = 0.13-0.19) and higher post-mTBI symptoms in all 4 PCSI-P symptom domains (ds = 0.23-0.35), relative to males. CONCLUSIONS: Attention-deficit/hyperactivity disorder-related postinjury exacerbations in parent-reported symptoms can be explained, in part, by elevated retrospective parent-reported ADHD-related pre-mTBI ratings. These results highlight the importance of assessing a patient's baseline symptoms post-mTBI. These data also indicate that ADHD status and sex should be considered when interpreting mTBI symptom severity during clinical evaluation of concussion.

The Impact of Language Switching Frequency on Attentional and Executive Functioning in Proficient Bilingual Adults.

Bilingual advantages in executive functions are well documented (see Bialystok, 2009; Dong & Li, 2015, for a review), but the specific aspects of bilingualism that underlie these advantages are unclear. The few studies conducted up until now on this subject (e.g., Hartanto & Yang, 2016; Prior & Gollan, 2011; Verreyt, Woumans, Vandelanotte, Szmalec, & Duyck, 2016) have suggested that the frequency of language switching may partially mediate this advantage. We further investigate the impact of oral language-switching frequency on the development of alerting, response inhibition and cognitive flexibility skills in proficient bilinguals. Two groups of proficient bilingual adults (21 low-frequency language switchers and 21 high-frequency language switchers), matched for age, gender, second-language proficiency and socio-cultural status, participated in the study. Tasks assessing alerting, response inhibition and cognitive flexibility were administered. Our results revealed that high-frequency language switchers responded more quickly in the task assessing cognitive flexibility. No group effect was found on the tasks assessing alerting and response inhibition. These results suggest that language-switching frequency is likely an underlying factor in the enhanced cognitive flexibility of proficient bilinguals.

[Formula: see text] Neurocognition in children with cognitive disengagement syndrome: accurate but slow.

Cognitive disengagement syndrome (CDS), previously termed sluggish cognitive tempo (SCT), is characterized by excessive daydreaming, mental confusion, and slowed behavior or thinking. Prior research has found inconsistent relations between CDS and neurocognition, though most studies have used small or ADHD-defined samples, non-optimal measures of CDS, and/or examined limited neurocognitive domains. Accordingly, this study examined the association of parent- and teacher-reported CDS symptoms using a comprehensive neurocognitive battery in a sample of 263 children (aged 8-12) selected with a range of CDS symptomatology. Parents and teachers provided ratings of CDS and ADHD inattentive (ADHD-IN) symptoms. Path analyses were conducted to examine CDS and ADHD-IN as unique predictors of neurocognitive functioning after covarying for age, sex, and family income. CDS symptoms were uniquely associated with slower performance across a range of cognitive domains, including verbal inhibition, rapid naming/reading, planning, divided attention, and set shifting. In contrast, ADHD-IN symptoms were uniquely associated with poorer performance on a Go/NoGo task (inhibition/distractibility), visual scanning and discrimination, and interference control. Findings from the current study, amongst the first to recruit children based on levels of CDS symptomatology, provide the strongest evidence to date that the neurocognitive phenotype of CDS is characterized by slowed cognitive processing, and add to its validity as a separate syndrome from ADHD. If replicated, these findings have implications for assessment, treatment, and school accommodations for CDS. Neuroimaging studies exploring the neurobiological basis of CDS are also needed.

Verbal Memory Interference in Attention-Deficit Hyperactivity Disorder: A Meta-Analytic Review.

OBJECTIVE: Interference control is used to overcome conflict among competing memory representations and may contribute to memory difficulties in ADHD. This meta-analytic review examined memory interference to evaluate susceptibility to proactive, retroactive, and memory control interference among those with ADHD. METHOD: Twenty studies (1987-2019) examining verbal memory interference in ADHD met inclusion criteria (age: 8-36 years). Proactive and retroactive interference indices were extracted from list-learning tasks, and memory control indices were extracted from experimental paradigms (e.g., directed-forgetting). RESULTS: Children with ADHD were less affected by proactive interference (g=-0.53, 95% CI [-0.75, -0.31]), whereas no significant differences were found in adults (g=0.13, 95% CI [-0.02, 0.28]). Adults and children with ADHD exhibited more retroactive interference (g=0.17, 95% CI [0.05, 0.29]) and performed worse on memory control tasks (g=0.35, 95% CI [0.08, 0.62]) relative to controls. CONCLUSION: Differences in verbal memory interference control in ADHD were observed but effects were different depending upon interference type and participant age.

Effect of Subconcussive Head Impact Exposure and Jugular Vein Compression on Behavioral and Cognitive Outcomes after a Single Season of High-School Football: A Prospective Longitudinal Trial.

This prospective longitudinal trial aimed to (1) determine the role of head impact exposure on behavioral/cognitive outcomes, and (2) assess the protective effect(s) of a jugular vein compression (JVC) collar on behavioral/cognitive outcomes after one season of high-school football. Participants included 284 male high-school football players aged 13-18 years enrolled from seven Midwestern high-schools. Schools were allocated to the JVC collar intervention (four teams, 140 players) or no collar/no intervention control (three teams, 144 players) condition. Head impact exposure was measured throughout the season using CSx accelerometers. Outcome measures included post-season parent and adolescent report on Strengths and Weaknesses of ADHD Symptoms and Normal Behavior Scale (SWAN) and Post-Concussion Symptom Inventory (PCSI), as well as adolescent performance on Attention Network Task (ANT), digital Trail Making Task (dTMT), and Cued Switching task. No significant effect of head impact exposure or JVC collar use on post-season SWAN or PCSI scores or performance on dTMT and Cued Switching task were noted. There was no effect of head impact exposure on ANT performance; however, the JVC collar group had greater post-season Alerting network scores than the no collar group (p = 0.026, d = 0.22). Findings provide preliminary evidence that the JVC collar may provide some protection to the alerting attention system. These findings should be interpreted cautiously as a greater understanding of the long-term sequelae of head impact exposure and the role of cumulative head impact exposure behavioral/cognitive outcomes is required.

Working Memory Capacity and ADHD Symptoms in Boys: Examining the Heterogeneity of Working Memory Functioning Using Latent Profile Analysis.

Recent studies demonstrate that working memory (WM) is integral to etiological models of ADHD; however, significant questions persist regarding the relation between WM performance across tasks with varying cognitive demands and ADHD symptoms. The current study incorporates an individual differences approach to WM heterogeneity (i.e., latent profile analysis) to (a) identify differential profiles of WM across the phonological and visuospatial WM subsystems; and (b) characterize differences in symptom presentation among WM profiles. Parent and teacher ratings of child behavior, obtained for boys with (n=51) and without (n=38) a diagnosis of ADHD, were compared across latent classes of visuospatial and phonological WM performance. Latent profile analysis identified three classes of WM functioning: Low WM, Moderate WM, and High WM. Membership in the Low and Moderate WM classes was associated with greater levels of parent- and teacher-rated inattentive and hyperactive symptoms. While 84% of the ADHD group were assigned to the Low and Moderate WM classes, more than a quarter of children without ADHD exhibited Moderate WM limitations. Collectively, these findings extend prior work suggesting that there is substantial heterogeneity in WM functioning in children with and without ADHD and that these differences contribute to the expression of symptoms of inattention and hyperactivity.

Phonological Working Memory Deficits in ADHD Revisited: The Role of Lower Level Information-Processing Deficits in Impaired Working Memory Performance.

OBJECTIVE: The current study dissociates lower level information-processing abilities (visual registration/encoding, visual-to-phonological conversion, and response output) and examines their contribution to ADHD-related phonological working memory (PHWM) deficits. METHOD: Twenty children with ADHD and 15 typically developing (TD) children completed tasks assessing PHWM, visual registration/encoding, visual-to-phonological conversion, and response output. RESULTS: Relative to TD children, children with ADHD exhibited deficient visual registration/encoding ( d = 0.60), visual-to-phonological conversion ( d = 0.56), and PHWM ( d = 0.72) but faster response output ( d = -0.66). Bias-corrected, bootstrapped mediation analyses revealed that visual registration/encoding, but not visual-to-phonological conversion, partially mediated ADHD-related PHWM impairments. In contrast, faster response output in children with ADHD served as a suppressor variable, such that greater PHWM deficits were observed in children with ADHD after controlling for their faster response output ( d = 0.72 vs. 0.85). CONCLUSION: Results implicate both lower level (visual registration/encoding) and higher order (PHWM) impairments in ADHD. Implications for designing educationally relevant cognitive interventions are discussed.

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

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

Inattentive Behavior in Boys with ADHD during Classroom Instruction: the Mediating Role of Working Memory Processes.

Children with ADHD exhibit clinically impairing inattentive behavior during classroom instruction and in other cognitively demanding contexts. However, there have been surprisingly few attempts to validate anecdotal parent/teacher reports of intact sustained attention during 'preferred' activities such as watching movies. The current investigation addresses this omission, and provides an initial test of how ADHD-related working memory deficits contribute to inattentive behavior during classroom instruction. Boys ages 8-12 (M = 9.62, SD = 1.22) with ADHD (n = 32) and typically developing boys (TD; n = 30) completed a counterbalanced series of working memory tests and watched two videos on separate assessment days: an analogue math instructional video, and a non-instructional video selected to match the content and cognitive demands of parent/teacher-described 'preferred' activities. Objective, reliable observations of attentive behavior revealed no between-group differences during the non-instructional video (d = -0.02), and attentive behavior during the non-instructional video was unrelated to all working memory variables (r = -0.11 to 0.19, ns). In contrast, the ADHD group showed disproportionate attentive behavior decrements during analogue classroom instruction (d = -0.71). Bias-corrected, bootstrapped, serial mediation revealed that 59% of this between-group difference was attributable to ADHD-related impairments in central executive working memory, both directly (ER = 41%) and indirectly via its role in coordinating phonological short-term memory (ER = 15%). Between-group attentive behavior differences were no longer detectable after accounting for ADHD-related working memory impairments (d = -0.29, ns). Results confirm anecdotal reports of intact sustained attention during activities that place minimal demands on working memory, and indicate that ADHD children's inattention during analogue classroom instruction is related, in large part, to their underdeveloped working memory abilities.

Attention-Deficit/Hyperactivity Disorder-Related Deficits and Psychostimulant Medication Effects on Comprehension of Audiovisually Presented Educational Material in Children.

Objective: We aimed to (1) examine differences in observed visual attention and motor activity, as well as comprehension of a science video between children with and without attention-deficit/hyperactivity disorder (ADHD) and (2) explore if psychostimulant medication improves ADHD behaviors and comprehension of a science video in children with ADHD. Method: Children aged 7-11 with (n = 91) and without (n = 45) ADHD watched a science video and then completed a comprehension test. Then, children with ADHD began a 4-week within-subject, randomized, double-blind crossover trial of methylphenidate (MPH). At post-testing, children were randomized to receive placebo or their optimal dosage, watched another science film, and completed a comprehension test. Results: Children with ADHD exhibited higher rates of motor activity during, and worse comprehension of material discussed within, the science video. Mediation models revealed that increased motor activity suppressed between-group differences in comprehension. MPH improved comprehension and visual attention, but not motor activity during the science video. Conclusion: Children with ADHD may benefit from MPH to improve comprehension of and sustained attention during audiovisually presented learning material.

Reading Comprehension in Boys with ADHD: The Mediating Roles of Working Memory and Orthographic Conversion.

Reading comprehension difficulties in children with ADHD are well established; however, limited information exists concerning the cognitive mechanisms that contribute to these difficulties and the extent to which they interact with one another. The current study examines two broad cognitive processes known to be involved in children's reading comprehension abilities-(a) working memory (i.e., central executive processes [CE], phonological short-term memory [PH STM], and visuospatial short-term memory [VS STM]) and (b) orthographic conversion (i.e., conversion of visually presented text to a phonological code)-to elucidate their unique and interactive contribution to ADHD-related reading comprehension differences. Thirty-one boys with ADHD-combined type and 30 typically developing (TD) boys aged 8 to 12 years (M = 9.64, SD = 1.22) were administered multiple counterbalanced tasks assessing WM and orthographic conversion processes. Relative to TD boys, boys with ADHD exhibited significant deficits in PH STM (d = -0.70), VS STM (d = -0.92), CE (d = -1.58), and orthographic conversion (d = -0.93). Bias-corrected, bootstrapped mediation analyses revealed that CE and orthographic conversion processes modeled separately mediated ADHD-related reading comprehension differences partially, whereas PH STM and VS STM did not. CE and orthographic conversion modeled jointly mediated ADHD-related reading comprehension differences fully wherein orthographic conversion's large magnitude influence on reading comprehension occurred indirectly through CE's impact on the orthographic system. The findings suggest that adaptive cognitive interventions designed to improve reading-related outcomes in children with ADHD may benefit by including modules that train CE and orthographic conversion processes independently and interactively.

Do programs designed to train working memory, other executive functions, and attention benefit children with ADHD? A meta-analytic review of cognitive, academic, and behavioral outcomes.

Children with ADHD are characterized frequently as possessing underdeveloped executive functions and sustained attentional abilities, and recent commercial claims suggest that computer-based cognitive training can remediate these impairments and provide significant and lasting improvement in their attention, impulse control, social functioning, academic performance, and complex reasoning skills. The present review critically evaluates these claims through meta-analysis of 25 studies of facilitative intervention training (i.e., cognitive training) for children with ADHD. Random effects models corrected for publication bias and sampling error revealed that studies training short-term memory alone resulted in moderate magnitude improvements in short-term memory (d=0.63), whereas training attention did not significantly improve attention and training mixed executive functions did not significantly improve the targeted executive functions (both nonsignificant: 95% confidence intervals include 0.0). Far transfer effects of cognitive training on academic functioning, blinded ratings of behavior (both nonsignificant), and cognitive tests (d=0.14) were nonsignificant or negligible. Unblinded raters (d=0.48) reported significantly larger benefits relative to blinded raters and objective tests (both p<.05), indicating the likelihood of Hawthorne effects. Critical examination of training targets revealed incongruence with empirical evidence regarding the specific executive functions that are (a) most impaired in ADHD, and (b) functionally related to the behavioral and academic outcomes these training programs are intended to ameliorate. Collectively, meta-analytic results indicate that claims regarding the academic, behavioral, and cognitive benefits associated with extant cognitive training programs are unsupported in ADHD. The methodological limitations of the current evidence base, however, leave open the possibility that cognitive training techniques designed to improve empirically documented executive function deficits may benefit children with ADHD.

Reaction time variability in ADHD: a meta-analytic review of 319 studies.

Individuals with ADHD are characterized as ubiquitously slower and more variable than their unaffected peers, and increased reaction time (RT) variability is considered by many to reflect an etiologically important characteristic of ADHD. The present review critically evaluates these claims through meta-analysis of 319 studies of RT variability in children, adolescents, and adults with ADHD relative to typically developing (TD) groups, clinical control groups, and themselves (subtype comparisons, treatment and motivation effects). Random effects models corrected for measurement unreliability and publication bias revealed that children/adolescents (Hedges' g=0.76) and adults (g=0.46) with ADHD demonstrated greater RT variability relative to TD groups. This increased variability was attenuated by psychostimulant treatment (g=-0.74), but unaffected by non-stimulant medical and psychosocial interventions. Individuals with ADHD did not evince slower processing speed (mean RT) after accounting for RT variability, whereas large magnitude RT variability deficits remained after accounting for mean RT. Adolescents and adults with ADHD were indistinguishable from clinical control groups, and children with ADHD were only minimally more variable than clinical control children (g=0.25). Collectively, results of the meta-analysis indicate that RT variability reflects a stable feature of ADHD and other clinical disorders that is robust to systematic differences across studies.