The Disruptive Behavior Disorders Rating Scale: Updated Factor Structure, Measurement Invariance, and National Caregiver Norms.

OBJECTIVE: To provide the first caregiver-report national norms for the Disruptive Behavior Disorders Rating Scale (DBDRS) and an updated evaluation of its factor structure and measurement invariance across child sex, informant sex, and child age. METHODS: Caregivers of children aged 5-12 years (N = 962) based in the United States completed the four DBDRS subscales. Using both severity scoring and dichotomous scoring procedures, confirmatory factor analyses supported a four-factor model of inattentive and hyperactive/impulsive symptoms, oppositional defiant symptoms, and conduct disorder symptoms. RESULTS: Measurement invariance was supported, indicating that the DBDRS functions similarly across demographic characteristics. Boys were reported to have more severe symptoms than girls (Cohen's d = 0.33 [inattention], 0.30 [hyperactivity/impulsivity], 0.18 [oppositional defiant disorder], 0.14 [conduct disorder]), female caregivers rated ADHD symptoms as more severe than male caregivers (ds = 0.15 and 0.19 for inattention and hyperactivity/impulsivity, respectively), and older children were reported to experience more inattention than younger children (d = 0.18). Overall, group differences were modest in magnitude. CONCLUSION: This psychometric study supports the continued use of the DBDRS in school-aged youth and will enhance the measure's clinical and research utility by providing the first caregiver-report norms.

A critical review of hot executive functioning in youth attention-deficit/hyperactivity disorder: Methodological limitations, conceptual considerations, and future directions.

Hot executive functioning (EF) - EF under emotionally or motivationally salient conditions - is a putative etiology of attention-deficit/hyperactivity disorder (ADHD), disruptive behavior problems (DBPs), and their related impairments. Despite two decades of research, the present study is the first review of the construct in youth ADHD, with a particular focus on the role of task design, age, and DBPs, as well as relevant conceptual and methodological considerations. While certain hot EF tasks have been investigated extensively (e.g., choice impulsivity), substantial inconsistency in measurement of the broader construct remains, severely limiting conclusions. Future research should a) consider the extent to which various hot EF tasks relate to one another, a higher order factor, and other related constructs; b) further investigate task design, particularly the elicitation of emotion or motivation and its anticipated effect on EF; and c) incorporate multiple levels of analysis to validate similarities and differences among tasks with regard to the affective experiences and cognitive demands they elicit. With improved measurement and conceptual clarity, hot EF has potential to advance the literature on etiological pathways to ADHD, DBPs and associated impairments and, more broadly, may represent a useful tool for understanding the influence of emotion and motivation on cognition.

The impact of ADHD symptom severity on reinforcement and punishment learning among adults.

Introduction: Aberrations in feedback learning are hypothesised to contribute to the behavioural disruptions and impairment of attention-deficit/hyperactivity disorder (ADHD). However, few studies have evaluated the relation of reward/punishment feedback and ADHD symptom severity on learning. The current study evaluates the differential effects of reward and punishment feedback on learning among adults with elevated ADHD. Methods: One hundred five participants self-reported their level of current ADHD symptoms and completed an innovative instrumental learning task. Results: Consistent with predictions, participants with low self-reported ADHD symptom severity benefitted equally from reward and punishment feedback during the learning task, whereas participants with high self-reported symptom severity performed better (indexed by accuracy on learning task) from reward than punishment feedback trials. Conclusions: Overall, adults with high self-reported symptom severity of ADHD learned more from reward-based feedback, which provides critical implications for motivational theories about ADHD, as well as for treatment protocols. Future work should examine the translatability of results within a treatment setting.

Inhibitory Control, Conduct Problems, and Callous Unemotional Traits in Children with ADHD and Typically Developing Children.

Compared children with CP/ADHD, CPCU/ADHD, ADHD-only, and controls on two measures of inhibitory control: a Simon/flanker task that measured response selection and a stop signal task that measured response inhibition. Results showed: (a) ADHD was associated with both measures of inhibitory control; (b) control children had better overall performance and ADHD-only had worse response selection than the CP groups; and (c) children with CPCU/ADHD had better response inhibition than children with ADHD-only or CP/ADHD. Results suggest inhibitory control dysfunction is associated with ADHD rather than CP and that response inhibition dysfunction distinguishes children with CP/ADHD from children with CPCU/ADHD.

Computational modeling reveals strategic and developmental differences in the behavioral impact of reward across adolescence.

Studies of reward effects on behavior in adolescence typically rely on performance metrics that confound myriad cognitive and non-cognitive processes, making it challenging to determine which process is impacted by reward. The present longitudinal study applied the diffusion decision model to a reward task to isolate the influence of reward on response caution from influences of processing and motor speed. Participants completed three annual assessments from early to middle adolescence (N = 387, 55% female, Mage  = 12.1 at Wave 1; Mage  = 13.1 at Wave 2, Mage  = 14.1 at Wave 3) and three annual assessments in late adolescence (Mages  = 17.8, 18.9, 19.9). At each assessment, participants completed a two-choice reaction time task under conditions of no-reward and a block in which points were awarded for speeded accuracy. Reward reduced response caution at all waves, as expected, but had a greater impact as teens moved from early to middle adolescence. Simulations to identify optimal response caution showed that teens were overly cautious in early adolescence but became too focused on speed over accuracy by middle adolescence. By late adolescence, participants adopted response styles that maximized reward. Further, response style was associated with both internalizing and externalizing symptoms in early-to-middle adolescence, providing evidence for the construct validity of a diffusion model approach in this developmental period.

Brief report: Evaluation of working memory deficits in children with ADHD using the NIH list sorting working memory task.

Variability in working memory (WM) task selection likely contributes to heterogeneity in effect size estimates of deficiencies in youth with attention-deficit/hyperactivity disorder (ADHD). This has resulted in the development of brief, easy to administer assessments such as the NIH List Sorting Working Memory (LSWM) task from the NIH Cognitive Toolbox in hopes of standardizing measurement of this construct. Unfortunately, substantial questions persist regarding the specific constructs being evaluated by this task (e.g., visuospatial [VS] or phonological [PH] WM) as well as the ability of this task to detect WM deficits in previously identified impaired groups (e.g., ADHD). The current study examines the extent to which the LSWM task is associated with VS and PHWM performance as well as symptoms of ADHD. Additionally, we examined the magnitude of differences between ADHD and Typically Developing (TD) youth on this task relative to empirically derived WM tasks utilized in the past. Forty-six children (25 ADHD, 21 TD) completed multiple WM tasks. The LSWM task was moderately associated with PHWM and demonstrated relatively weaker associations with VSWM. Symptoms of inattention and hyperactivity/impulsivity were unrelated to the LSWM task; whereas tasks assessing PH and VSWM were moderately associated with inattention and weakly associated with hyperactivity (VSWM only). No significant between-group differences in performance emerged on the LSWM task; however, significant large-magnitude group differences were observed on both the PH and VSWM tasks. These findings suggest that the LSWM task may lack the ability to detect WM difficulties in youth with ADHD.

Baseline performance moderates stimulant effects on cognition in youth with ADHD.

Attention-deficit/hyperactivity disorder is associated with impaired cognitive functioning and increased delay discounting (i.e., a stronger preference for immediate reward). At the group level, stimulant medication improves cognition and delay discounting, yet not all children exhibit problems in these domains, and previous work has not examined whether stimulant-induced improvements are moderated by baseline performance. To address this question in the current study, 82 children with attention-deficit/hyperactivity disorder (9-12 years old) attended a week-long research camp. On the baseline day (Monday), participants completed tasks of inhibitory control, visuospatial working memory, reaction time variability, and delay discounting. Children then completed a 3-day, randomized, double-blind, placebo-controlled trial of ∼1 mg/kg and 2 mg/kg long-acting methylphenidate (mean doses = 39.1 and 74.3 mg, respectively), during which they were readministered the battery of tasks. Cognitive composites (mean of inhibitory control, working memory, and reaction time variability performance) were created for the baseline and medication evaluation phases. As predicted, the extent to which cognition was improved with medication compared with placebo and with 2 mg/kg compared with 1 mg/kg was greatest among children with poorer baseline cognitive function. Children with stronger baseline cognition exhibited less improvement with methylphenidate compared with placebo and did not benefit from the 2 compared with the 1 mg/kg dose. In contrast, medication-related improvement in delay discounting was unrelated to baseline discounting. Given that improving cognitive function is one potential mechanisms by which stimulants exert their therapeutic effects, this study has significant implications for understanding how and for whom stimulant medication works. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Executive Functioning and Activity in Children: a Multimethod Examination of Working Memory, Inhibition, and Hyperactivity.

Two primary methods of quantifying executive functioning include self- or other-reports (i.e., questionnaire-based EF) and cognitive test performance (i.e., task-based EF). Despite their lack of concordance with one another and relatively inconsistent associations with attention-deficit/hyperactivity disorder (ADHD) symptoms, both approaches have been utilized in attempts to advance our understanding of the role of EF in symptoms of ADHD. The current study is the first to incorporate a direct assessment of behavior (i.e., actigraphy) to further clarify the relation between EF and hyperactivity using a multi-method approach in a sample of children with a range of ADHD symptoms. Fifty-two children between the ages of 8 and 12 completed a testing session during which performance on working memory and inhibition computerized tasks, as well as actigraphy data, were collected. Additionally, parent reports of hyperactivity/impulsivity, working memory, and inhibition were obtained. As expected, questionnaire-based measures of working memory and inhibition were strongly associated with parent-reported hyperactivity/impulsivity, whereas only the latter was associated significantly with mechanically assessed movement. In contrast, task-based working memory performance was more strongly associated with parent-reported hyperactivity/impulsivity relative to task-based inhibition. Further, both task-based working memory and task-based inhibition were similarly associated with mechanically-assessed movement. Finally, compared to questionnaire-based EF, both measures of task-based EF accounted for more variance in objectively-assessed movement. Collectively, these results highlight the measurement issues in the present literature, the importance of careful task and questionnaire design, and the value that alternative approaches (e.g., actigraphy) may provide with respect to advancing our understanding of EF.

Psychometric evaluation of the pediatric applied cognition scale in pediatric hematology/oncology.

Pediatric patients with hematology and oncology conditions often experience disease- and treatment-related neurocognitive deficits. Well-validated screening tools are critical for identifying patients experiencing cognitive impairments. The Pediatric Applied Cognition scale (PAC) Short Form, developed by the National Institutes of Health, assesses attention and memory concerns. The current study is the first to examine the psychometrics of the PAC in pediatric patients with hematology/oncology conditions. Pediatric patients (n = 222) and caregivers completed the PAC and self-report measures of psychosocial and academic functioning. Results revealed strong internal consistency for the Child (α = 0.81-0.89) and Parent (α = 0.92-0.95) PAC. More cognitive concerns on the Child/Parent PAC were associated with greater psychosocial concerns (e.g. anxiety, depression, and fatigue) and lower reported school grades. The Parent PAC incrementally predicted child reported symptoms of depression, mobility concerns, and school grades beyond the Child PAC. Overall, the PAC Short Form may be useful as an indicator of general academic and psychosocial concerns. Further research validating the PAC in relation to performance-based neurocognitive outcomes and academic achievement is needed in children treated for hematology/oncology conditions.

Which 'Working' Components of Working Memory aren't Working in Youth with ADHD?

Despite replicated evidence for working memory deficits in youth with ADHD, no study has comprehensively assessed all three primary 'working' subcomponents of the working memory system in these children. Children ages 8-13 with (n = 45) and without (n = 41) ADHD (40% female; Mage = 10.5; 65% Caucasian/Non-Hispanic) completed a counterbalanced battery of nine tasks (three per construct) assessing working memory reordering (maintaining and rearranging information in mind), updating (active monitoring of incoming information and replacing outdated with relevant information), and dual-processing (maintaining information in mind while performing a secondary task). Detailed analytic plans were preregistered. Bayesian t-tests indicated that, at the group level, children with ADHD exhibited significant impairments in working memory reordering (BF10 = 4.64 × 105; d = 1.34) and updating (BF10 = 9.49; d = 0.64), but not dual-processing (BF01 = 1.33; d = 0.37). Overall, 67%-71% of youth with ADHD exhibited impairment in at least one central executive working memory domain. Reordering showed the most ADHD-related impairment, with 75% classified as below average or impaired, and none demonstrating strengths. The majority of children with ADHD (52%-57%) demonstrated average or better abilities in the remaining two domains, with a notable minority demonstrating strengths in updating (8%) and dual-processing (20%). Notably, impairments in domain-general central executive working memory, rather than individual subcomponents, predicted ADHD severity, suggesting that common rather than specific working memory mechanisms may be central to understanding ADHD symptoms. These impairment estimates extend prior work by providing initial evidence that children with ADHD not only exhibit heterogeneous profiles across cognitive domains but also exhibit significant heterogeneity within subcomponents of key cognitive processes.

Working memory and information processing in ADHD: Evidence for directionality of effects.

OBJECTIVE: Children with ADHD demonstrate impaired performance on a wide range of neuropsychological tests. It is unclear, however, whether ADHD is associated with many neurocognitive deficits or whether a small number of impairment(s) broadly influence test performance. The current study tests competing model predictions regarding two candidate causal mechanisms in ADHD: information processing speed and working memory. METHOD: A well-characterized sample of 86 children (Mage = 10.52, SDage = 1.54; 34 girls; 64% Caucasian/Non-Hispanic) with ADHD (n = 45) and without ADHD (n = 41) completed eight fully crossed experimental tasks that systematically manipulated working memory (BF10 = 1.80 × 109³) and information processing speed (drift rate; BF10 = 7.61 × 106). RESULTS: Bayesian mixed-model ANOVAs indicated that increasing working memory demands produced significant reductions in information processing speed (drift rate; BF10 = 5.82 × 1096). In contrast, experimentally reducing children's information processing speed did not significantly change their working memory performance (BF10 = 1.31). ADHD status interacted with the working memory manipulation, such that the ADHD and non-ADHD groups showed equivalently high accuracy under the encoding-only conditions (BF01 = 3.45) but differed significantly under high working memory conditions (encoding + recall; BF10 = 19.58). Importantly, however, ADHD status failed to interact with (a) the working memory manipulation to differentially affect information processing speed and (b) the information processing speed manipulation to differentially affect working memory performance (all BF01 > 4.25). CONCLUSIONS: These findings indicate that top-down executive control exerts significant effects on children's ability to quickly process information, but that working memory deficits and slowed information processing speed appear to be relatively independent impairments in ADHD. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

What cognitive processes are "sluggish" in sluggish cognitive tempo?

OBJECTIVE: Sluggish cognitive tempo refers to a constellation of symptoms that include slowed behavior/thinking, reduced alertness, and getting lost in one's thoughts. Despite the moniker "sluggish cognitive tempo," the evidence is mixed regarding the extent to which it is associated globally with slowed (sluggish) mental (cognitive) information processing speed (tempo). METHOD: A well-characterized clinical sample of 132 children ages 8-13 years (M = 10.34, SD = 1.51; 47 girls; 67% White/non-Hispanic) were administered multiple, counterbalanced neurocognitive tests and assessed for sluggish cognitive tempo symptoms via multiple-informant reports. RESULTS: Bayesian linear regressions revealed significant evidence against associations between sluggish cognitive tempo and computationally modeled processing speed (BF01 > 3.70), and significant evidence for associations with slower working memory manipulation speed. These findings were consistent across parent and teacher models, with and without control for attention-deficit/hyperactivity disorder inattentive symptoms and IQ. There was also significant evidence linking faster inhibition speed with higher parent-reported sluggish cognitive tempo symptoms. CONCLUSIONS: These findings provide strong evidence against characterizing children with sluggish cognitive tempo symptoms as possessing a globally sluggish cognitive tempo. Instead, these symptoms appear to be related, to a significant extent, to executive dysfunction characterized by working memory systems that are too slow and inhibition systems that are too fast. Behaviorally, these findings suggest that requiring extra time to rearrange the active contents of working memory delays responding, whereas an overactive inhibition system likely terminates thoughts too quickly and therefore prevents intended behaviors from starting or completing, thereby giving the appearance that children are absent-minded or failing to act when expected. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Mind the gap: A review and recommendations for statistically evaluating Dual Systems models of adolescent risk behavior.

According to Dual Systems models (Casey et al., 2008; Luna and Wright, 2016; Steinberg, 2008), a rapidly-developing socioemotional system and gradually-developing cognitive control system characterize adolescent brain development. The imbalance hypothesis forwarded by Dual Systems models posits that the magnitude of the imbalance between these two developing systems should predict the propensity for engaging in a variety of risk behaviors. The current integrative review argues that the excitement generated by the imbalance hypothesis and its implications for explaining adolescent risk behaviors has not been meet with equal efforts to rigorously test this hypothesis. The goal of the current review is to help guide the field to consider appropriate and rigorous methods of testing the imbalance hypothesis. First, we review the analytic approaches that have been used to test the imbalance hypothesis and outline statistical and conceptual limitations of these approaches. Next, we discuss the utility of two longitudinal analytic approaches (Latent Difference Scores and Growth Mixture Modeling) for testing the imbalance hypothesis. We utilize data from a large community adolescent sample to illustrate each approach and argue that Latent Difference Scores and Growth Mixture Modeling approaches enhance the specificity and precision with which the imbalance hypothesis is evaluated.

The development of inhibitory control in adolescence and prospective relations with delinquency.

INTRODUCTION: Despite the central role of inhibitory control in models of adolescent development, few studies have examined the longitudinal development of inhibitory control within adolescence and its prospective association with maladaptive outcomes. The current study evaluated: 1) growth in inhibitory control from early- to middle-adolescence, and 2) the relation between inhibitory control and later delinquency. METHODS: Participants included 387 parent-child dyads (11-13 years old at Wave 1; 55% female; USA). Across three annual assessments, teens completed the Stop Signal Task (SST), and parents completed the Inhibitory Control subscale of the Early Adolescent Temperament Questionnaire-Revised. Teens self-reported their delinquent behaviors in early (Mage = 12.1) and middle adolescence (Mage = 14.1) and emerging adulthood (Mage = 18.2). RESULTS: Latent growth curve models indicated that SST performance improved curvilinearly from early to middle adolescence (ages 11-15), with growth slowing around middle adolescence. However, no growth in parent-reported inhibitory control was observed. Lower task-based and parent-reported inhibitory control in early adolescence predicted greater increases in delinquency from middle adolescence to emerging adulthood. However, rate of growth in task-based inhibitory control was unrelated to later delinquency. CONCLUSIONS: This longitudinal study provides a novel examination of the development of inhibitory control across early and middle adolescence. Results suggest that the degree to which inhibitory control confers risk for later delinquency may be captured in early adolescence, consistent with neurodevelopmental accounts of delinquency risk. Differences across assessment tools also highlight the need for careful measurement considerations in future work, as task-based measures may be better suited to capture within-person changes over time.

Inhibitory Control and Information Processing in ADHD: Comparing the Dual Task and Performance Adjustment Hypotheses.

Inhibition is a key neurocognitive domain in ADHD that is commonly assessed with the stop-signal task. The stop-signal involves both "go" and "stop" trials; previous research indicates that response times are reliably slower to "go" trials during tasks with vs. without intermittent "stop" trials. However, it is unclear whether this pattern reflects deliberate slowing to maximize inhibitory success (performance adjustment hypothesis) and/or disrupted bottom-up information processing due to increased cognitive demands (dual-task hypothesis). Given the centrality of "go" responding for estimating children's inhibitory speed, finding that children with ADHD slow differently -or for different reasons- has the potential to inform cognitive and self-regulatory theories of ADHD. The current study used a carefully-controlled experimental design to assess the mechanisms underlying stop signal-related slowing in ADHD. Children ages 8-13 with (n = 81) and without ADHD (n = 63) completed the stop-signal task and a control task that differed only in the presence/absence of "stop" trials. Using drift-diffusion modeling, Bayesian repeated-measures ANOVAs revealed a pattern consistent with the performance adjustment hypothesis, such that children adopted more cautious response strategies (BF10 = 6221.78; d = 0.38) but did not show changes in processing speed (BF01 = 3.08; d = 0.12) or encoding/motor speed (BF01 = 5.73; d = 0.07) when inhibition demands were introduced. Importantly, the ADHD/Non-ADHD groups showed equivalent effects of intermittent "stop" trials (BF01 = 4.30-5.56). These findings suggest intact self-regulation/performance monitoring in the context of adapting to increased inhibitory demands in ADHD, which has important implications for the continued isolation of potential mechanisms associated with ADHD symptoms and impairment.

Parent and child neurocognitive functioning predict response to behavioral parent training for youth with ADHD.

Parental cognitive functioning is thought to play a key role in parenting behavior and may inform response to behavioral intervention. This open-label pilot study examined the extent to which parent and child cognition impacted response to behavioral parent training for children with ADHD. Fifty-four participants (27 parent-child dyads; Mages = 10.6 and 45.2 for children and parents, respectively) completed tasks assessing visuospatial and phonological working memory, inhibitory control, and choice-reaction speed at pre-treatment. Drift diffusion modeling decomposed choice-reaction time data into indicators of processing speed (drift rate) and response caution (boundary separation). Parents completed a 10-week manualized behavioral parent training program. Primary outcomes were pre- and post-treatment child ADHD and conduct problem severity, and parent-reported relational frustration and parenting confidence. Bayesian multiple regressions assessed parent and child cognitive processes as predictors of post-treatment outcomes, controlling for pre-treatment behavior. Better child visuospatial and phonological WM and higher parental response caution were associated with greater reductions in inattention. For conduct problems, better parental self-regulation (stronger inhibitory control and greater response caution) predicted fewer post-treatment conduct problems. Higher parental response caution also predicted lower post-treatment relational frustration and higher parental confidence. Bayesian evidence supported no relation between parent and child cognitive functions and treatment-related changes in hyperactivity. This pilot study demonstrates that cognitive processes central to etiologic theories of ADHD and models of parenting behavior can be successfully integrated into treatment outcome research to inform which families are most likely to benefit from behavioral interventions. This study demonstrates the feasibility of bridging the translational research gap between basic and applied clinical science and facilitates research on the role of cognition in psychosocial interventions.

How do stimulant treatments for ADHD work? Evidence for mediation by improved cognition.

BACKGROUND: Stimulant medications such as methylphenidate (MPH) are the frontline treatment for Attention-Deficit/Hyperactivity Disorder (ADHD). Despite their well-documented efficacy, the mechanisms by which stimulants improve clinical outcomes are not clear. The current study evaluated whether MPH effects on classroom behavior were mediated by improved cognitive functioning. METHODS: Children with ADHD (n = 82; 9-12 years old) participated in a week-long summer research camp, consisting of cognitive testing, classroom periods, and recreational activities. After a baseline day, participants completed a 3-day randomized, double-blind, placebo-controlled trial of MPH (at doses approximating 0.3 and 0.6 mg/kg of immediate-release MPH dosed TID). Cognitive domains included inhibitory control (Stop Signal Task and prepulse inhibition of startle), attention (Continuous Performance Task and reaction time variability), and working memory (forward and backward spatial span). Clinical outcomes included math seatwork productivity and teacher-rated classroom behavior. A within-subjects path-analytic approach was used to test mediation. MPH-placebo and dose-response contrasts were used to evaluate drug effects. RESULTS: Methylphenidate improved seatwork productivity and teacher ratings (ds = 1.4 and 1.1) and all domains of cognition (ds = 0.3-1.1). Inhibitory control (Stop Signal Task, SST) and working memory backward uniquely mediated the effect of MPH (vs. placebo) on productivity. Only working memory backward mediated the impact of MPH on teacher-rated behavior. The dose-response (0.6 vs. 0.3 mg/kg) effects were more modest for clinical outcomes (ds = 0.4 and 0.2) and cognition (ds = 0-0.3); there was no evidence of cognitive mediation of the clinical dose-response effects. CONCLUSIONS: These findings are novel in demonstrating that specific cognitive processes mediate clinical improvement with stimulant treatment for ADHD. They converge with work on ADHD theory, neurobiology, and treatment development in suggesting that inhibitory control and working memory may be mechanisms of stimulant treatment response in ADHD. More work is necessary to evaluate the degree to which these findings generalize to chronic treatment, a broader array of clinical outcomes, and nonstimulant treatments.

Acute Stimulant Treatment and Reinforcement Increase the Speed of Information Accumulation in Children with ADHD.

The current studies utilized drift diffusion modeling (DDM) to examine how reinforcement and stimulant medication affect cognitive task performance in children with ADHD. In Study 1, children with (n = 25; 88 % male) and without ADHD (n = 33; 82 % male) completed a 2-choice discrimination task at baseline (100 trials) and again a week later under alternating reinforcement and no-reinforcement contingencies (400 trials total). In Study 2, participants with ADHD (n = 29; 72 % male) completed a double-blind, placebo-controlled trial of 0.3 and 0.6 mg/kg methylphenidate and completed the same task utilized in Study 1 at baseline (100 trials). Children with ADHD accumulated information at a much slower rate than controls, as evidenced by a lower drift rate. Groups were similar in nondecision time and boundary separation. Both reinforcement and stimulant medication markedly improved drift rate in children with ADHD (ds = 0.70 and 0.95 for reinforcement and methylphenidate, respectively); both treatments also reduced boundary separation (ds = 0.70 and 0.39). Reinforcement, which emphasized speeded accuracy, reduced nondecision time (d = 0.37), whereas stimulant medication increased nondecision time (d = 0.38). These studies provide initial evidence that frontline treatments for ADHD primarily impact cognitive performance in youth with ADHD by improving the speed/efficiency of information accumulation. Treatment effects on other DDM parameters may vary between treatments or interact with task parameters (number of trials, task difficulty). DDM, in conjunction with other approaches, may be helpful in clarifying the specific cognitive processes that are disrupted in ADHD, as well as the basic mechanisms that underlie the efficacy of ADHD treatments.

Relating lab to life: Decrements in attention over time predict math productivity among children with ADHD.

A child's ability to sustain attention over time (AOT) is critical in attention-deficit/hyperactivity disorder (ADHD), yet no prior work has examined the extent to which a child's decrement in AOT on laboratory tasks relates to clinically-relevant behavior. The goal of this study is to provide initial evidence for the criterion validity of laboratory assessments of AOT. A total of 20 children with ADHD (7-12 years of age) who were enrolled in a summer treatment program completed two lab attention tasks (a continuous performance task and a self-paced choice discrimination task) and math seatwork. Analyses focused on relations between attention task parameters and math productivity. Individual differences in overall attention (OA) measures (averaged across time) accounted for 23% of the variance in math productivity, supporting the criterion validity of lab measures of attention. The criterion validity was enhanced by consideration of changes in AOT. Performance on all laboratory attention measures deteriorated as time-on-task increased, and individual differences in the decrement in AOT accounted for 40% of the variance in math productivity. The only variable to uniquely predict math productivity was from the self-paced choice discrimination task. This study suggests that attention tasks in the lab do predict a clinically-relevant target behavior in children with ADHD, supporting their use as a means to study attention processes in a controlled environment. Furthermore, this prediction is improved when attention is examined as a function of time-on-task and when the attentional demands are consistent between lab and life contexts.

Reinforcement and Stimulant Medication Ameliorate Deficient Response Inhibition in Children with Attention-Deficit/Hyperactivity Disorder.

This study examined the degree to which reinforcement, stimulant medication, and their combination impact response inhibition in children with Attention-Deficit/Hyperactivity Disorder (ADHD). Across three studies, participants with ADHD (n = 111, 25 girls) and typically-developing (TD) controls (n = 33, 6 girls) completed a standard version of the stop signal task (SST) and/or a reinforcement-manipulation SST with performance-contingent points. In two of these studies, these tasks were performed under placebo or 0.3 and 0.6 mg/kg methylphenidate (MPH) conditions. Cross-study comparisons were conducted to test hypotheses regarding the separate and combined effects of reinforcement and methylphenidate on response inhibition among children with ADHD relative to TD controls. Baseline response inhibition was worse among children with ADHD compared to controls. MPH produced dose-related improvements in response inhibition in children with ADHD; compared to non-medicated TD controls, 0.3 mg/kg MPH normalized deficient response inhibition, and 0.6 mg/kg MPH resulted in better inhibition in children with ADHD. Reinforcement improved response inhibition to a greater extent for children with ADHD than for TD children, normalizing response inhibition. The combination of MPH and reinforcement improved response inhibition among children with ADHD compared to reinforcement alone and MPH alone, also resulting in normalization of response inhibition despite repeated task exposure. Deficient response inhibition commonly observed in children with ADHD is significantly improved with MPH and/or reinforcement, normalizing inhibition relative to TD children tested under standard conditions.