Hyperactivity, or excess gross motor activity, is considered a core and ubiquitous characteristic of ADHD. Alternate models question this premise, and propose that hyperactive behavior reflects, to a large extent, purposeful behavior to cope with environmental demands that interact with underlying neurobiological vulnerabilities. The present review critically evaluates the ubiquity and environmental modifiability of hyperactivity in ADHD through meta-analysis of 63 studies of mechanically measured activity level in children, adolescents, and adults with ADHD relative to typically developing (TD) groups. Random effects models corrected for publication bias confirmed elevated gross motor activity in ADHD (d = 0.86); surprisingly, neither participant age (child vs. adult) nor the proportion of each ADHD sample diagnosed with the Inattentive subtype/presentation moderated this effect. In contrast, activity level assessed during high cognitive load conditions in general (d = 1.14) and high executive functioning demands in particular (d = 1.39) revealed significantly higher effect sizes than activity level during low cognitive load (d = 0.36) and in-class schoolwork (d = 0.50) settings. Low stimulation environments, more rigorous diagnostic practices, actigraph measurement of movement frequency and intensity, and ADHD samples that included fewer females were also associated with larger effects. Overall, the results are inconsistent with DSM-5 and ADHD models that a) describe hyperactivity as ubiquitous behavior, b) predict a developmental decline in hyperactivity, or c) differentiate subtypes/presentations according to perceived differences in hyperactive behavior. Instead, results suggest that the presence and magnitude of hyperactive behavior in ADHD may be influenced to a considerable extent by environmental factors in general, and cognitive/executive functioning demands in particular.

Objective: Executive function deficits are well-established in ADHD. Unfortunately, replicated evidence indicates that executive function training for ADHD has been largely unsuccessful. We hypothesized that this may reflect insufficient targeting, such that extant protocols do not sufficiently and specifically target the neurocognitive systems associated with phenotypic ADHD behaviors/impairments. Method: Children with ADHD ages 8–12 (M = 10.41, SD = 1.46; 12 girls; 74% Caucasian/Non-Hispanic) were randomized with allocation concealment to either central executive training (CET; n = 25) or newly developed inhibitory control training (ICT; n = 29). Detailed data analytic plans were preregistered. Results: Both treatments were feasible/acceptable based on training duration, child-reported ease of use, and parent-reported high satisfaction. CET was superior to ICT for improving its primary intervention targets: phonological and visuospatial working memory (d = 0.70–0.84). CET was also superior to ICT for improving go/no-go (d = 0.84) but not stop-signal inhibition. Mechanisms of change analyses indicated that CET-related working memory improvements produced significant reductions in the primary clinical endpoints (objectively assessed hyperactivity) during working memory and inhibition testing (indirect effects: β ≥ −.11; 95% CIs exclude 0.0). CET was also superior to ICT on 3 of 4 secondary clinical endpoints (blinded teacher-rated ADHD symptoms; d = 0.46–0.70 vs. 0.16–0.42) and 2 of 4 feasibility/acceptability clinical endpoints (parent-reported ADHD symptoms; d = 0.96–1.42 vs. 0.45–0.65). CET-related gains were maintained at 2–4 month follow-up; ICT-related gains were maintained for attention problems but not hyperactivity/impulsivity per parent report. Conclusions: Results support the use of CET for treating executive function deficits and targeting ADHD behavioral symptoms in children with ADHD. Findings for ICT were mixed at best and indicate the need for continued development/study.

Childhood ADHD is associated with impairments in peer, family, and academic functioning. Although impairment is required for diagnosis, children with ADHD vary significantly in the areas in which they demonstrate clinically significant impairment. However, relatively little is known about the mechanisms and processes underlying these individual differences. The current study examined neurocognitive predictors of heterogeneity in peer, family, and academic functioning in a well-defined sample of 44 children with ADHD ages 8–13 (M = 10.31, SD = 1.42; 31 boys, 13 girls; 81% Caucasian). Reliable change analysis indicated that 98% of the sample demonstrated objectively defined impairment on at least one assessed outcome measure; 65% were impaired in two or all three areas of functioning. ADHD children with quantifiable deficits in academic success and family functioning performed worse on tests of working memory (d = 0.68 to 1.09), whereas children with impaired parent-reported social functioning demonstrated slower processing speed (d = 0.53). Dimensional analyses identified additional predictors of peer, family, and academic functioning. Working memory abilities were associated with individual differences in all three functional domains, processing speed predicted social functioning, and inhibitory control predicted family functioning. The current results add to a growing literature implicating neurocognitive abilities not only in explaining behavioral differences between ADHD and non-ADHD groups, but also in the substantial heterogeneity in ecologically valid functional outcomes associated with the disorder.

Objective Working memory deficits have been linked experimentally and developmentally with ADHD-related symptoms/impairments. Unfortunately, substantial evidence indicates that extant working memory training programs fail to improve these symptoms/impairments. We hypothesized that this discrepancy may reflect insufficient targeting, such that extant protocols do not adequately engage the specific working memory components linked with the disorder’s behavioral/functional impairments. Method The current study describes the development, empirical basis, and initial testing of central executive training (CET) relative to gold-standard behavioral parent training (BPT). Children with ADHD ages 8–13 (M=10.43, SD=1.59; 21 girls; 76% Caucasian/Non-Hispanic) were treated using BPT (n=27) or CET (n=27). Detailed data analytic plans for the pre/post design were preregistered. Primary outcomes included phonological and visuospatial working memory, and secondary outcomes included actigraphy during working memory testing and two distal far-transfer tasks. Multiple feasibility/acceptability measures were included. Results The BPT and CET samples did not differ on any pre-treatment characteristics. CET was rated as highly acceptable by children, and was equivalent to BPT in terms of feasibility/acceptability as evidenced by parent-reported high satisfaction, low barriers to participation, and large ADHD symptom reductions. CET was superior to BPT for improving working memory (group x time d=1.06) as hypothesized. CET was also superior to BPT for reducing actigraph-measured hyperactivity during visuospatial working memory testing and both distal far-transfer tasks (group x time d=0.74). Conclusions Results provide strong support for continued testing of CET and, if replicated, would support recent hypotheses that next-generation ADHD cognitive training protocols may overcome current limitations via improved targeting.

Objective: Executive functions are commonly measured using rating scales and performance tests. However, replicated evidence indicates weak/nonsignificant cross-method associations that suggest divergent rather than convergent validity. The current study is the first to investigate the relative concurrent and predictive validities of executive function tests and ratings using (a) multiple gold-standard performance tests, (b) multiple standardized rating scales completed by multiple informants, and (c) both performance-based and ratings-based assessment of academic achievement-a key functional outcome with strong theoretical links to executive function. Method: A well-characterized sample of 136 children oversampled for ADHD and other forms of child psychopathology associated with executive dysfunction (ages 8 -13; 68% Caucasian/non-Hispanic) completed a counterbalanced series of executive function and academic tests. Parents/teachers completed executive function ratings; teachers also rated children's academic performance. Results: The executive function tests/ratings association was modest (r ϭ .30) and significantly lower than the academic tests/ratings association (r ϭ .63). Relative to ratings, executive function tests showed significantly higher cross-method predictive validity and significantly better within-method prediction; executive function ratings failed to demonstrate improved within-method prediction. Both methods uniquely predicted academic tests and ratings. Conclusion: These findings replicate prior evidence that executive function tests and ratings cannot be used interchangeably as executive function measures in research and clinical applications, while suggesting that executive function tests may have superior validity for predicting academic behavior/achievement.