Tanya N. Antonini

Evidence for Higher Reaction Time Variability for Children With ADHD on a Range of Cognitive Tasks Including Reward and Event Rate Manipulations

OBJECTIVE The purpose of the research study was to examine the manifestation of variability in reaction times (RT) in children with attention deficit hyperactivity disorder (ADHD) and to examine whether RT variability presented differently across a variety of neuropsychological tasks, was present across the two most common ADHD subtypes, and whether it was affected by reward and event rate (ER) manipulations. METHOD Children with ADHD-combined type (n = 51), ADHD-predominantly inattentive type (n = 53), and 47 controls completed five neuropsychological tasks (Choice Discrimination Task, Child Attentional Network Task, Go/No-Go task, Stop Signal Task, and N-back task), each allowing trial-by-trial assessment of RTs. Multiple indicators of RT variability including RT standard deviation, coefficient of variation and ex-Gaussian tau were used. RESULTS Children with ADHD demonstrated greater RT variability than controls across all five tasks as measured by the ex-Gaussian indicator tau. There were minimal differences in RT variability across the ADHD subtypes. Children with ADHD also had poorer task accuracy than controls across all tasks except the Choice Discrimination task. Although ER and reward manipulations did affect childrens RT variability and task accuracy, these manipulations largely did not differentially affect children with ADHD compared to controls. RT variability and task accuracy were highly correlated across tasks. Removing variance attributable to RT variability from task accuracy did not appreciably affect between-groups differences in task accuracy. CONCLUSIONS High RT variability is a ubiquitous and robust phenomenon in children with ADHD.

Reaction Time Variability in ADHD: A Review

For the past decade, intra-individual variability in reaction times on computerized tasks has become a central focus of cognitive research on Attention-Deficit/Hyperactivity Disorder (ADHD). Numerous studies document increased reaction time variability among children and adults with ADHD, relative to typically developing controls. However, direct comparisons with other disorders with heightened reaction time variability are virtually nonexistent, despite their potential to inform our understanding of the phenomenon. A growing literature examines the sensitivity of reaction time variability to theoretically and clinically relevant manipulations. There is strong evidence that stimulus treatment reduces reaction time variability during a range of cognitive tasks, but the literature is mixed regarding the impact of motivational incentives and variation in stimulus event rate. Most studies of reaction time variability implicitly assume that heightened reaction time variability reflects occasional lapses in attention, and the dominant neurophysiological interpretation suggests this variability is linked to intrusions of task-negative brain network activity during task performance. Work examining the behavioral and neurophysiological correlates of reaction time variability provides some support for these hypotheses, but considerably more work is needed in this area. Finally, because conclusions from each of domains reviewed are limited by the wide range of measures used to measure reaction time variability, this review highlights the need for increased attention to the cognitive and motivational context in which variability is assessed and recommends that future work always supplement macro-level variability indices with metrics that isolate particular components of reaction time variability.

Effects of Stimulant Medication, Incentives, and Event Rate on Reaction Time Variability in Children With ADHD

This study examined the effects of methylphenidate (MPH) on reaction time (RT) variability in children with attention deficit hyperactivity disorder (ADHD). Using a broad battery of computerized tasks, and both conventional and ex-Gaussian indicators of RT variability, in addition to within-task manipulations of incentive and event rate (ER), this study comprehensively examined the breadth, specificity, and possible moderators of effects of MPH on RT variability. A total of 93 children with ADHD completed a 4-week within-subject, randomized, double-blind, placebo-controlled crossover trial of MPH to identify an optimal dosage. Children were then randomly assigned to receive either their optimal MPH dose or placebo after which they completed five neuropsychological tasks, each allowing trial-by-trial assessment of RTs. Stimulant effects on RT variability were observed on both measures of the total RT distribution (ie, coefficient of variation) as well as on an ex-Gaussian measure examining the exponential portion of the RT distribution (ie, τ). There was minimal, if any, effect of MPH on performance accuracy or RT speed. Within-task incentive and ER manipulations did not appreciably affect stimulant effects across the tasks. The pattern of significant and pervasive effects of MPH on RT variability, and few effects of MPH on accuracy and RT speed suggest that MPH primarily affects RT variability. Given the magnitude and breadth of effects of MPH on RT variability as well as the apparent specificity of these effects of MPH on RT variability indicators, future research should focus on neurophysiological correlates of effects of MPH on RT variability in an effort to better define MPH pharmacodynamics.

Parent- Teacher Agreement on ADHD Symptoms Across Development

Parent-teacher agreement on attention-deficit/hyperactivity disorder (ADHD) symptom ratings ranges from low to moderate. Most studies evaluating parent-teacher agreement have not assessed measurement invariance across raters. Hence, it is unclear whether discordance across raters is due to differing ADHD constructs across raters or other factors (e.g., subjective differences across raters). Additionally, the effect of development on parent-teacher agreement is relatively unknown. To address these limitations, the present study used parent and teacher ADHD ratings from a large (N = 6,659) developmentally diverse (ages 4-17) sample. Using exploratory structural equation modeling on half the sample, and then confirmatory factor analysis (CFA) on the other half of the sample, confirmed a 2-factor structure with significant cross-loadings for the 18 ADHD symptoms. CFA invariance analyses demonstrated that the 2-factor symptom structure was similar across raters and age groups. After confirming measurement invariance, the correlation between latent factors within and across raters was examined for each age group as well as across age groups. Parents reported greater severity of ADHD symptoms than did teachers, and both parents and teachers reported higher levels of hyperactivity/impulsivity in younger children than in older children and consistent levels of inattention across development. Finally, correlations between parent-teacher ratings of like factors were weak for inattention and moderate-strong for hyperactivity/impulsivity, and the magnitude of parent-teacher agreement did not vary across development. In conclusion, while parent and teacher ratings of ADHD behaviors are only weakly to moderately correlated, each reporter provides unique and valid clinical information as it relates to ADHD symptom presentation.

Examining predictors of reaction times in children with ADHD and normal controls

A microanalysis of task events in a common go/no-go task was completed to examine how task events impact individual reaction times. Predictors of long reaction times were analyzed to better understand increased intra-individual variability (IIV) among children with ADHD compared with normal controls. Sixty-five children with ADHD and 65 normal controls matched on gender, ethnicity, and age completed a go/no-go task. Children across both groups were slower before and after omission errors than all other trials. They were also slower on the trial before successfully inhibiting their response to no-go trials. Children with ADHD exhibited a pronounced slowing on trials prior to omission errors and trials prior to successful inhibitions compared with the normal control group. Pre-error slowing in children with ADHD may represent the beginning stages of attentional disengagement that subsequently results in the absence of responding (i.e., errors of omission or successful inhibition). While these event-related increases in reaction time explain some of the increased IIV observed in children with ADHD, the removal of these trials did not remove the pronounced between-group differences in IIV, suggesting that additional unmeasured processes are contributing to IIV in children with ADHD.

Impact of Distraction on the Driving Performance of Adolescents With and Without Attention-Deficit/Hyperactivity Disorder

IMPORTANCE This study extends the literature regarding attention-deficit/hyperactivity disorder (ADHD)-related driving impairments to a newly licensed, adolescent population. OBJECTIVE To investigate the combined risks of adolescence, ADHD, and distracted driving (cell phone conversation and text messaging) on driving performance. DESIGN, SETTING, AND PARTICIPANTS Adolescents aged 16 to 17 years with (n = 28) and without (n = 33) ADHD engaged in a simulated drive under 3 conditions (no distraction, cell phone conversation, and texting). During each condition, one unexpected event (eg, another car suddenly merging into drivers lane) was introduced. INTERVENTIONS Cell phone conversation, texting, and no distraction while driving. MAIN OUTCOMES AND MEASURES Self-report of driving history, average speed, standard deviation of speed, standard deviation of lateral position, and braking reaction time during driving simulation. RESULTS Adolescents with ADHD reported fewer months of driving experience and a higher proportion of driving violations than control subjects. After controlling for months of driving history, adolescents with ADHD demonstrated more variability in speed and lane position than control subjects. There were no group differences for braking reaction time. Furthermore, texting negatively impacted the driving performance of all participants as evidenced by increased variability in speed and lane position. CONCLUSIONS To our knowledge, this study is one of the first to investigate distracted driving in adolescents with ADHD and adds to a growing body of literature documenting that individuals with ADHD are at increased risk for negative driving outcomes. Furthermore, texting significantly impairs the driving performance of all adolescents and increases existing driving-related impairment in adolescents with ADHD, highlighting the need for education and enforcement of regulations against texting for this age group.

Behavioral Correlates of Reaction Time Variability in Children With and Without ADHD

OBJECTIVE Reaction time (RT) variability is often purported to indicate behavioral attention. This study seeks to examine whether RT variability in children with Attention Deficit Hyperactivity Disorder (ADHD) is associated with observed behavioral indicators of attention. METHOD One-hundred 47 participants with and without ADHD completed five computerized neuropsychological tasks and an analog math task. Linear mixed models were utilized to examine the relationship between observations of behavioral inattention during the analog task and measures of RT variability from the neuropsychological tasks. RESULTS Significant associations were observed between RT variability and mean duration of on-task behavior on the analog math task. Secondary analyses indicated that on-task behavior during the math task was also related to accuracy on the neuropsychological tasks. CONCLUSIONS RT variability, especially the portion of RT variability characterized by long RTs, appears to measure a cognitive phenomenon that relates to successful on-task academic behavior across children with and without ADHD. The relationship between RT variability and on-task behavior is present across multiple neuropsychological tasks and does not appear to be moderated by age, sex, or the presence of anxiety or depression.

An online positive parenting skills programme for paediatric traumatic brain injury: feasibility and parental satisfaction.

We examined the feasibility of and parental satisfaction with a training programme for parents with children who had suffered traumatic brain injury (TBI). Families who did not have a home computer and/or webcam were loaned the necessary equipment. Skype was used for videoconferencing. After the initial treatment session in the familys home, the remaining nine sessions were conducted online. Each session had two parts: (1) a self-guided web session with information about a particular skill; (2) a videoconference session with the therapist. Three of the 20 families (15%) dropped out prior to the final 6-month follow-up visit. Of the remaining 17 families, 13 (65% of those enrolled) completed 9–14 sessions. Almost all of the caregivers (87%) said that the Skype sessions were helpful compared to a conventional office visit. Almost all parents were satisfied with the programme and the technology that was used. Parental satisfaction with the programme was not influenced by prior computer ownership or comfort with technology. The programme appears to be feasible for a wide range of parents of children with TBI and provides an alternative to conventional office-based sessions that may not be accessible to all families.

A Pilot Randomized Trial of an Online Parenting Skills Program for Pediatric Traumatic Brain Injury: Improvements in Parenting and Child Behavior

This pilot study examined changes in parenting skills and child behavior following participation in an online positive parenting skills program designed for young children with traumatic brain injury (TBI). Thirty-seven families with a child between 3 and 9 years of age who sustained a moderate to severe TBI were randomly assigned to one of two interventions: online parenting skills training (n=20) or access to Internet resources on managing brain injury (n=17). Parent-child interaction observations and parent ratings of child behavior were collected pre- and post-treatment. Generalized estimating equations and mixed models were used to examine changes in parenting skills and child behavior problems as well as the moderating role of family income on treatment response. Participants in the parenting skills group displayed significant improvements in observed positive parenting skills relative to participants in the Internet resource group. Income moderated improvements in parent ratings of child behavior, with participants in the low-income parenting skills group and high-income Internet resource group reporting the greatest improvements in behavior. This is the first randomized controlled trial examining online parenting skills training for families of young children with TBI. Improvements in positive parenting skills and child behavior support the utility of this intervention, particularly for families from lower socioeconomic backgrounds.

Neurocognitive and Behavioral Predictors of Math Performance in Children With and Without ADHD

Objective: This study examined neurocognitive and behavioral predictors of math performance in children with and without ADHD. Method: Neurocognitive and behavioral variables were examined as predictors of (a) standardized mathematics achievement scores, (b) productivity on an analog math task, and (c) accuracy on an analog math task. Results: Children with ADHD had lower achievement scores but did not significantly differ from controls on math productivity or accuracy. N-back accuracy and parent-rated attention predicted math achievement. N-back accuracy and observed attention predicted math productivity. Alerting scores on the attentional network task predicted math accuracy. Mediation analyses indicated that n-back accuracy significantly mediated the relationship between diagnostic group and math achievement. Conclusion: Neurocognition, rather than behavior, may account for the deficits in math achievement exhibited by many children with ADHD.