Selective inhibition in children with attention-deficit hyperactivity disorder off and on stimulant medication

Selective inhibition requires discrimination between auditory signals and is assessed using a modification of the stop-signal task. Selective inhibition was assessed in a group of 59 clinic-referred, DSM-IV-diagnosed children with attention-deficit hyperactivity disorder (ADHD) and compared to that of a community sample of 59 children. Methylphenidate (MPH) effects on selective inhibition were assessed in a subset of the ADHD sample that participated in an acute, randomized, placebo-controlled, crossover trial with 3 fixed doses of MPH. Children with ADHD performed more poorly than controls on the majority of selective stop-signal task parameters: they exhibited more anticipatory (invalid) responses, with less accurate and more variable responses on the response execution task, as well as a slower selective inhibition process. MPH improved speed of both inhibition and response execution processes; it also reduced variability of response execution and decreased nonselective inhibition. On the one hand, findings are consistent with purported inhibition deficit in ADHD, but on the other hand, suggest that neither the impairment itself, nor MPH effects, were restricted to inhibition.     

Relationships among compulsive hoarding, trauma, and attention-deficit/hyperactivity disorder

The current study investigated aspects of post-traumatic stress disorder and attention deficit/ hyperactivity disorder (ADHD) among hoarders. Compared to a sample of 36 controls, hoarders (n=26) reported a significantly greater number of different types of trauma, more frequent traumatic experiences, more symptoms of inattention, hyperactivity, and greater comfort derived from possessions. These findings are consistent with previous reports of extensive comorbidity associated with hoarding behaviors, and may reflect the potential usefulness of assessing PTSD and ADHD symptoms at the outset of hoarding treatments, as well as considering alternative pharmacological interventions.     

Working Memory Deficits in Boys with Attention-deficit/Hyperactivity Disorder (ADHD): The Contribution of Central Executive and Subsystem Processes

The current study investigated contradictory findings from recent experimental and meta-analytic studies concerning working memory deficits in ADHD. Working memory refers to the cognitive ability to temporarily store and mentally manipulate limited amounts of information for use in guiding behavior. Phonological (verbal) and visuospatial (nonverbal) working memory were assessed across four memory load conditions in 23 boys (12 ADHD, 11 typically developing) using tasks based on Baddeley's (Working memory, thought, and action, Oxford University Press, New York, 2007) working memory model. The model posits separate phonological and visuospatial storage and rehearsal components that are controlled by a single attentional controller (CE: central executive). A latent variable approach was used to partial task performance related to three variables of interest: phonological buffer/rehearsal loop, visuospatial buffer/rehearsal loop, and the CE attentional controller. ADHD-related working memory deficits were apparent across all three cognitive systems--with the largest magnitude of deficits apparent in the CE--even after controlling for reading speed, nonverbal visual encoding, age, IQ, and SES.     

Written expression in boys with ADHD: The mediating roles of working memory and oral expression

The written expression difficulties experienced by children with ADHD are widely recognized; however, scant empirical evidence exists concerning the cognitive mechanisms and processes underlying these deficiencies. The current study investigated the independent and potentially interactive contributions of two developmentally antecedent cognitive processes – viz., working memory (WM) and oral expression – hypothesized to influence written expression ability in boys. Thirty-three boys with ADHD-Combined Presentation and 27 neurotypical (NT) boys 8–12 years of age were administered standardized measures of oral and written expression, and multiple counterbalanced tasks to assess WM central executive (CE) processes, WM phonological short-term memory (PH STM), and WM visuospatial short-term memory (VS STM). Bias-corrected bootstrapped mediation analyses revealed a significant mediation effect, wherein the independent and interactive effects of PH STM and oral expression collectively explained 76% of the diagnostic status to written expression relation. The implications of the obtained results for clinical practice suggest that children with ADHD may benefit by incorporating a blended approach that simultaneously strengthens PH STM capacity and oral expression abilities as antecedents to engaging in writing-related activities.     

ADHD outside the laboratory: boys' executive function performance on tasks in videogame play and on a visit to the zoo

One current theory of attention-deficit/hyperactivity disorder (ADHD) proposes that a primary deficit in behavioral inhibition gives rise to secondary deficits in 4 executive functions and motor control. To date, empirical support for this model is based primarily on laboratory-based cognitive methods. This study assessed behavioral inhibition and executive functioning in children with ADHD in 2 real-life contexts: videogames (motor-skill target game, cognitively demanding adventure game) and an outing at the zoo (route tasks). Participants were a community sample of 57 boys diagnosed with ADHD (20 inattentive, 37 combined type) and 57 normally developing control boys, matched individually for age and nonverbal IQ. Operationally defined measures of behavioral inhibition and specific executive functions were derived from these activities and assessed under contrasting conditions of low or high working memory and distractor loads. There were no group differences in basic motor skills on the target game, nor in terms of the ability to inhibit a prepotent or ongoing response in the adventure videogame. However, boys with ADHD exhibited more self-talk, more effortful response preparation, and completed fewer challenges in the latter videogame. Also, they manifested inhibition deficits in terms of interference control during the route task at the zoo and took longer to complete the tasks. Typically, these differences were greatest under conditions of high working memory and distractor loads. Findings from this study suggest that cognitive difficulties in ADHD may be context dependent and that ADHD is associated with deficits in some but not all aspects of behavioral inhibition.     

Categorization behaviour in adults,adolescents, and attention-deficit/hyperactivity disorder adolescents: A comparative investigation

Although significant progress has been made with respect to our understanding of categorization and concept learning behaviour in adults, much less is known about how this key capacity plays out with respect to more restrictive populations. This is unfortunate because much may be revealed about the nature of concept learning by examining the limits exhibited by special populations. With this tenet in mind, in what follows, we investigated key aspects of concept learning in terms of the unexplored comparative performance of three populations—adults, adolescents, and adolescents with attention-deficit/hyperactivity disorder (ADHD). To do so, we employed a novel parainformative experimental task involving categorical stimuli with four objects defined over three dimensions. The learning difficulty ordering for these types of three-dimensional stimuli has proven robust and has been replicated by several researchers. Indeed, in our experiment, we observed the same concept learning ordering in adults and adolescents, but not in ADHD adolescents: For example, the latter group showed greatly impaired categorization performance on stimuli characterized by an “exclusive-or” rule. However, categorization performance on such type of stimuli indicated good reliability in discriminating between adolescents with and without ADHD (receiver-operating characteristic, ROC?=?.82). We accurately predicted and accounted for these results using generalized invariance structure theory (GIST; Vigo, 2013. The GIST of concepts. Cognition, 129, 138–162), which posits that organisms detect invariance patterns in stimuli that are necessary precursors to concept formation.     

Time Perception: Modality and Duration Effects in Attention-Deficit/Hyperactivity Disorder (ADHD)

Time perception performance was systematically investigated in adolescents with and without attention-deficit/hyperactivity disorder (ADHD). Specifically, the effects of manipulating modality (auditory and visual) and length of duration (200 and 1000 ms) were examined. Forty-six adolescents with ADHD and 44 controls were administered four duration discrimination tasks and two control tasks, and a set of standardized measures. Participants with ADHD had higher thresholds than controls on all of the duration discrimination tasks, with the largest effect size obtained on the visual 1000 ms duration discrimination task. No group differences were observed on the control tasks. Visual–spatial memory was found to be a significant predictor of visual and auditory duration discrimination at longer intervals (1000 ms) in the ADHD sample, whereas auditory verbal working memory predicted auditory discrimination at longer intervals (1000 ms) in the control sample. These group differences suggest impairments in basic timing mechanisms in ADHD.     

Hyperactivity in boys with attention deficit/hyperactivity disorder (ADHD): the association between deficient behavioral inhibition, attentional processes, and objectively measured activity

Contemporary models of ADHD hypothesize that hyperactivity reflects a byproduct of inhibition deficits. The current study investigated the relationship between children's motor activity and behavioral inhibition by experimentally manipulating demands placed on the limited-resource inhibition system. Twenty-two boys (ADHD = 11, TD = 11) between the ages of 8 and 12 years completed a conventional stop-signal task, two choice-task variants (no-tone, ignore-tone), and control tasks while their motor activity was measured objectively by actigraphs placed on their nondominant wrist and ankles. All children exhibited significantly higher activity rates under all three experimental tasks relative to control conditions, and children with ADHD moved significantly more than typically developing children across conditions. No differences in activity level were observed between the inhibition and noninhibition experimental tasks for either group, indicating that activity level was primarily associated with basic attentional rather than behavioral inhibition processes.     

Multiple family therapy for Chinese families of children with attention deficit hyperactivity disorder (ADHD): treatment efficacy from the children’s perspective and their subjective experiences

This paper reports the results of our study that assessed the treatment efficacy of multiple family therapy (MFT) from the perspective of participating Chinese children with attention deficit hyperactivity disorder (ADHD) and identified their subjective experiences. Forty‐three children with ADHD in the experimental group (EG) completed a forty‐two‐hour MFT, whilst forty‐five children with ADHD in the control group (CG) had attended two writing classes scheduled three months apart that were similar to those of the MFT. Data from the outcome study were gathered using standardized questionnaires and data from the qualitative study were drawn from thirteen children with ADHD who had completed the MFT and attended the focus group interviews (n = 5) or individual interviews (n = 8) conducted in the post‐treatment phase. The results of the Paired sample t‐test and MANOVA indicated no significant changes on the scores for the four measures adopted (perception of competence, hopefulness, parent‐child relationship and perceived social support) in the pre‐ and post‐treatment for the EG and the CG. Five themes emerged from the narratives of children with ADHD, which revealed the children’s subjective experiences with the MFT: (a) full of fun; (b) building friendships through common experiences; (c) a happy family time; (d) safe space; and (e) positive parental responses and communications.