Disentangling Deficits in Adults With Attention-Deficit/Hyperactivity Disorder

A lack of inhibitory control has been suggested to be the core deficit in children with attention deficit hyperactivity disorder (ADHD). This means that a primary deficit in behavioral inhibition mediates a cascade of secondary deficits in other executive functions, such as arousal regulation. Clinical observations have revealed that with increasing age symptoms of hyperactivity and impulsivity decline at a higher rate than those of inattention. This might imply that a deficit in attention rather than a lack of inhibitory control is the major feature in adult ADHD. To study whether an attentional or inhibitory deficit predominates, the stop-signal task and the stop-change task were presented to 24 adults with ADHD combined subtype and 24 controls. Relative to controls, the stop-signal reaction time (SSRT) was significantly more prolonged than the go-stimulus reaction time (RT) in patients with ADHD. This disproportionate elongation of the SSRT was comparable across tasks, even though the stop-change task exerted more complex (or at least different) demands on the inhibitory system than the stop-signal task. ADHD patients had a higher proportion of choice errors, possibly reflecting more premature responses. Specifically in the stop-change task, patients had more variable choice responses and made more inappropriate change responses, which may also reflect enhanced impulsivity. The results support a core deficit in behavioral inhibition in adults with ADHD. We further suggest that there is more evidence for a critical role of deficient inhibitory control in adults than in children with ADHD.

Tourette Syndrome (TS) has previously been associated with deficits in inhibitory control (IC). However, studies on IC in individuals with TS have produced conflicting results. In the present study, we investigated IC, comparing the Stop Signal Reaction Time (SSRT) measure with parent and teacher ratings of daily life IC in 169 children aged 8–12 (60 with TS, 60 typically developing controls, 27 with attention-deficit/hyperactivity disorder (ADHD), and 22 with TS + ADHD). We further investigated associations of IC with TS and ADHD symptom severity. Children with TS showed intact SSRT performance, but impairments in daily life IC, as reported by parents and teachers. For the latter, we observed a staircase distribution of groups, with the healthy controls presenting with the best IC, followed by TS, TS + ADHD, and finally ADHD. Dimensional analyses indicated a strong association between ADHD severity and both measures of IC. Our results indicate that children with TS are not impaired in a laboratory-based measure of IC, although some difficulties were evident from measures of everyday behaviour, which may in part be due to parents and teachers interpreting tics as disinhibited behaviour. Comorbid ADHD or the severity of subthreshold ADHD symptomatology appeared to account for IC deficits.

BackgroundAltered brain activity that has been observed in attention deficit hyperactivity disorder (ADHD) while performing cognitive control tasks like the stop signal task (SST) has generally been interpreted as reflecting either weak (under-active) or compensatory (over-active) versions of the same functions as in healthy controls. If so, then regional activities that correlate with the efficiency of inhibitory control (i.e. stop signal reaction time, SSRT) in healthy subjects should also correlate with SSRT in ADHD. Here we test the alternate hypothesis that BOLD (blood-oxygen-level-dependent) differences might instead reflect the redirection of neural processing resources normally used for task-directed inhibitory control, towards actively managing symptomatic behaviour. If so, then activities that correlate with SSRT in TD should instead correlate with inattentive and hyperactive symptoms in ADHD.MethodsWe used fMRI (functional magnetic resonance imaging) in 14 typically developing (TD) and 14 ADHD adolescents performing the SST, and in a replication sample of 14 healthy adults. First, we identified significant group BOLD differences during all phases of activity in the SST (i.e. warning, response, reactive inhibition, error detection and post-error slowing). Next, we correlated these phases of activity with SSRT in TD and with SSRT, inattentive and hyperactive symptom scores in ADHD. We then identified whole brain significant correlations in regions of significant group difference in activity.ResultsOnly three regions of significant group difference were correlated with SSRT in TD and replication groups (left and right inferior frontal gyri (IFG) during error detection and hypothalamus during post-error slowing). Consistent with regions of altered activity managing symptomatic behaviour instead of task-directed behaviour, left IFG correlated with greater inattentive score, right IFG correlated with lower hyperactive score and hypothalamus correlated with greater inattentive score and oppositely correlated with SSRT compared to TD.ConclusionsStimuli that elicit task-directed integration of neural processing in healthy subjects instead appear to be directing integrated function towards managing symptomatic behaviour in ADHD. The ability of the current approach to determine whether altered neural activities reflect comparable functions in ADHD and control groups has broad implications for the development and monitoring of therapeutic interventions.

According to the balance model of self-regulation, dysfunction of the inhibitory control and reward processing might be a behavioral marker for addiction and problematic behaviors. Although several studies have separately examined the inhibitory control or reward processing of individuals exhibiting problematic Internet use (PIU), no study has explored these two functions simultaneously to examine the potential imbalance of these functions. This study aimed to investigate whether the self-regulatory failure of PIU individuals results from deficits in both inhibitory control [indexed with the stop signal reaction time (SSRT) in a stop signal task] and risk taking with losses (measured as the acceptance rates of risky gables or the ratio of win/loss in a mixed gambles task). The results revealed that PIU individuals, compared with controls, showed decreased SSRT and increased error rates as well as reduced risk taking with losses. Correlational analyses revealed a significant positive relationship between the SSRT and risk taking with losses. These findings suggest that both the inhibitory control and reward functions are impaired in PIU individuals and reveal an association between these two systems. These results strengthen the balance model of self-regulation theory’s argument that deficits in inhibitory control and risk taking with losses may assist in identifying risk markers for early diagnosis, progression, and prediction of PIU.

Background/Objectives: Attention-Deficit Hyperactivity Disorder (ADHD) is an immensely heterogeneous developmental disorder, uniquely impacting each individual. Physical movement is a promising adjunct behavioral treatment that can promote executive functioning in children with ADHD. The current study used neuroimaging and behavioral techniques to investigate the impact of movement during executive functioning on dorsolateral prefrontal cortical (DLPFC) activity and inhibitory control in children with ADHD, with particular focus on key individual difference factors in ADHD, such as subtype, severity, and gender. Methods: Twenty-eight children with ADHD completed a Stroop task while remaining stationary (stationary condition) and while desk cycling (movement condition). Simultaneous functional near-infrared spectroscopy (fNIRS) recorded oxygenated and deoxygenated changes in hemoglobin within the left DLPFC. Participants were categorized into ADHD subtype (hyperactive/impulsive, inattention, combined), ADHD severity (low, moderate, high), and gender (male, female). Results: Those with the hyperactive and combined ADHD subtypes, those with high ADHD severity, and males with ADHD showed greater DLPFC activation when engaging in movement during executive functioning compared to remaining stationary. In contrast, those with the inattentive ADHD subtype, those with low-to-moderate ADHD severity, and females with ADHD showed greater DLPFC activation when remaining stationary during executive functioning compared to engaging in movement. Inhibitory control improved in the stationary condition for females who were predominantly inattentive. Conclusions: This work underscores the importance of considering individual difference factors in ADHD when designing physical activity interventions, as treatment efficacy may vary.

Event Abstract Back to Event Brain pathways underlying Response Inhibition and Response Caution Renate Thienel1*, Elise Mansfield1, Patrick S. Cooper1, Andrew Heathcote1, Birte Forstmann2, Pat Michie1, Gavin Cooper1 and Frini Karayanidis1 1 School of Psychology, University of Newcastle, Australia 2 University of Amsterdam, Netherlands Background: Our previous findings suggest that the striatum is instrumental in mediating response caution in a task switching paradigm (Mansfield et al., J. Neurosci 2011, 31:14688-92), and that structural integrity in two separate fronto-striatal networks are associated with adopting an overall more risky or more cautious response threshold. In the present study, we examine whether a similar network underlies response inhibition, as operationalized by a stop signal task. Response inhibition has been shown to be mediated by cortical and subcortical structures within the inferior frontal lobe and the subthalamic nucleus, respectively. We investigate whether structural integrity measures in these regions can explain the relationship between stop signal related event related potential (ERP) components and estimates of stop signal reaction time (SSRT). Finally the relationship between, and the differential structural pathways contributing to, response threshold adjustment (task-switching paradigm) and stop signal response time will be examined. Methods: Diffusion weighted Imaging (DWI), ERP and behavioural data has been collected in 16 healthy participants (24.5 years, 5 male). A correlational analysis was performed for the ERPs and the behavioural measures of both tasks (task switching and stop signal task). Tract based spatial statistics (TBSS) of the DWI data was performed to compare the white matter pathways associated with response thresholds adjustment (task-switching task), and response inhibition (stop-signal task) respectively. These regions were then used to explain variation in ERP data. Results/Discussion: The integrity within distinct structural pathways (DWI data) explained the relationship between (1) ERP measures and response threshold adjustment and (2) ERP measures and SSRTs. Distinct fronto-basal ganglia pathways mediated threshold setting and response suppression. Keywords: task-switching, stop signal task, DWI, fronto-striatal circuits, response inhibition Conference: ACNS-2013 Australasian Cognitive Neuroscience Society Conference, Clayton, Melbourne, Australia, 28 Nov - 1 Dec, 2013. Presentation Type: Poster Topic: Executive Processes Citation: Thienel R, Mansfield E, Cooper PS, Heathcote A, Forstmann B, Michie P, Cooper G and Karayanidis F (2013). Brain pathways underlying Response Inhibition and Response Caution. Conference Abstract: ACNS-2013 Australasian Cognitive Neuroscience Society Conference. doi: 10.3389/conf.fnhum.2013.212.00145 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Sep 2013; Published Online: 25 Nov 2013. * Correspondence: Dr. Renate Thienel, School of Psychology, University of Newcastle, Newcastle, Australia, renate.thienel@newcastle.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Renate Thienel Elise Mansfield Patrick S Cooper Andrew Heathcote Birte Forstmann Pat Michie Gavin Cooper Frini Karayanidis Google Renate Thienel Elise Mansfield Patrick S Cooper Andrew Heathcote Birte Forstmann Pat Michie Gavin Cooper Frini Karayanidis Google Scholar Renate Thienel Elise Mansfield Patrick S Cooper Andrew Heathcote Birte Forstmann Pat Michie Gavin Cooper Frini Karayanidis PubMed Renate Thienel Elise Mansfield Patrick S Cooper Andrew Heathcote Birte Forstmann Pat Michie Gavin Cooper Frini Karayanidis Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Inhibitory control is a key executive function and has been studied extensively using the stop signal task. By applying a simple race model that posits an independent race between a GO process responsible for initiation of responses and a STOP process responsible for inhibition of responses, one can estimate how long it takes an individual to inhibit an ongoing response, the stop signal reaction time. Here, we examined how stop signal reaction time can be affected by working memory. Participants engaged in a dual task; they completed a stop signal task under low and high working memory load conditions. Working memory capacity was also measured. We found that the STOP process was lengthened in the high, compared to the low, working memory load condition, as evidenced by differences in stop signal reaction time. The GO process was unaffected and working memory capacity could not account for differences across the load conditions. These results indicate that inhibitory control can be influenced by placing demands on working memory.

Cognitive models of attention deficit hyperactivity disorder (ADHD) have traditionally centered on deficits in inhibitory control and motivation. A substantial body of empirical research supports impairments in both domains: children with ADHD exhibit elevated commission error rates, prolonged stop-signal reaction time, and a strong preference for smaller immediate rewards over larger delayed ones. In the first part of this review, we synthesize key findings from behavioral and task-state functional neuroimaging studies that characterize these deficits, highlighting how deficits in inhibitory control and motivation/reward systems manifest across tasks and contexts. We further examine evidence on the interplay between the two systems and how their interaction is altered in children with ADHD. In the second part, we introduce recent advances in cognitive and computational neuroscience that extend classic neurocognitive models by incorporating dynamic perspectives. Specifically, we describe the dynamic dual-control framework, which distinguishes between proactive and reactive inhibitory control, and highlight dynamics of trial-by-trial adaptive response strategy adjustment. We also review emerging computational models that can identify latent brain states and their evolution during task performance, revealing novel neurodynamic mechanisms that may underlie cognitive instability in ADHD. Additionally, we discuss pharmacological studies that shed light on how the inhibitory control and motivation/reward systems are modulated by medication. Finally, we address current limitations and challenges in ADHD research, with a particular focus on task-state functional neuroimaging, and propose future directions for advancing the field. By integrating dynamic modeling approaches with established neurocognitive frameworks, this review aims to deepen our understanding of the brain mechanisms underlying ADHD and to inform the development of more precise and effective interventions.

Diagnosis of Attention Deficit Hyperactivity Disorder by Using MR Imaging and Radiomics: A Potential Tool for Clinicians.

Inhibitory control dysfunction in nicotine dependence and the influence of short-term abstinence

Patients with attention‐deficit/hyperactivity disorder (ADHD) are often diagnosed with comorbid substance misuse (SM), which is associated with poor treatment efficacy. Although literature indicates similar inhibitory control deficits in both conditions, it is unclear whether SM in ADHD exaggerates pre‐existing deficits, with additive or distinct impairments in patients. Our aim was to examine SM effects on inhibitory control in ADHD. Behavioural and functional magnetic resonance imaging (fMRI) data from a stop‐signal task were compared across ADHD patients with and without SM (ADHD + SM and ADHD‐only, respectively) and controls (n = 33/group; 79 males, mean age 18.02 ± 2.45). To limit substance use disorder (SUD) trait effects, groups were matched for parental SUD. Overall, we found worse performance for ADHD‐only and/or ADHD + SM compared with controls but no difference between the ADHD groups. Moreover, the ADHD groups showed decreased frontostriatal and frontoparietal activity during successful and failed stop trials. There were no differences between the ADHD groups in superior frontal nodes, but there was more decreased activation in temporal/parietal nodes in ADHD‐only compared with ADHD + SM. During go‐trials, ADHD + SM showed decreased activation in inferior frontal nodes compared with ADHD‐only and controls. Findings during response inhibition showed deficits in inhibition and attentional processes for ADHD patients with and without SM. Despite no evidence for SM effects during response inhibition, results during go‐trials suggest distinct effects on nodes that are associated with several executive functions. Future studies should investigate whether distinct deficits in ADHD + SM relate to poor treatment results and can direct development of distinct ADHD treatment strategies for these patients.

ABSTRACTImpulsivity is a core feature of attention-deficit hyperactivity disorder (ADHD). It has been conceptualized in a number of different ways. In the current article, we examine how the new concept of “waiting impulsivity”, which refers to premature responding before a scheduled target appears, adds to our understanding of impulsivity in ADHD. Sixty children (8–12 years old; 30 ADHD; 30 typically developing controls) completed the 4-choice serial reaction time task, a measure of waiting impulsivity, alongside tasks measuring inhibitory control and temporal discounting and questionnaires measuring behavioral disorder symptoms, delay aversion, and various aspects of impulsivity. A multiple logistic regression model was used to explore the contribution of the primary task outcomes to predict group membership. Children with ADHD displayed more waiting impulsivity and less inhibitory control; they did not differ in temporal discounting. There was no correlation between waiting impulsivity and inhibitory control. Waiting impulsivity was correlated with parent-reported ratings of hyperactivity/impulsivity, inattention, oppositional defiant disorder (ODD), and conduct disorder (CD) and with self-reported delay aversion ratings. Only waiting impulsivity was a significant predictor of ADHD status. In conclusion, waiting impulsivity is distinct from inhibitory control deficits and predicts ADHD status independently of it. Future research needs to examine the relationship with delay aversion and ODD/CD more thoroughly.

Inhibitory control deficits are known to be characteristic of Oppositional Defiant Disorder (ODD), Conduct Disorder (CD), and Attention-Deficit/Hyperactivity Disorder (ADHD); but it is unclear whether children with ODD/CD have inhibitory control problems independent of ADHD comorbidity. Previous reviews of inhibitory control and ODD/CD have only focused on one type of measure of inhibitory control or used non-clinical samples. The current meta-analysis explored inhibitory control problems of children with ODD/CD by systematically reviewing studies where children have a diagnosis of ODD and/or CD. Comparisons were made across 25 studies between children with ODD/CD, ODD/CD + ADHD, ADHD, and healthy controls (HC) on various measures of inhibitory control and ADHD symptomatology to explore impacts of ADHD comorbidity. A small significant effect (g = -0.58, p < .001) suggested children with ODD/CD are likely to have more difficulties with inhibitory control than healthy children. However, comparisons between clinical groups suggested this effect may be due to ADHD symptomatology present in each group. As difficulties with inhibitory control are similar, across clinical groups, a dimensional approach to understanding ODD/CD and ADHD may be more useful to consider in future diagnostic criteria. Similarities across clinical groups highlight that therapeutic approaches that assist children with disruptive behaviours could benefit from teaching children and their families how to cope with inhibitory control deficits.

Driving a car requires a complex combination of various cognitive functions (e.g., visual perception, motor control, decision making, and others), and deficits in any of these processes may compromise driving safety. Amongst these, executive functions such as inhibitory control, task switching, and decision-making are important, as they enable drivers to process information from their surroundings and respond appropriately to changing road conditions. Although previous research has focused on laboratory measures of individual executive functions, it remains unclear whether performance on such laboratory tests readily translates to actual on-the-road driving performance, especially since drivers' skill levels can vary widely, based on their driving frequency. To this end, we divided 30 participants into two categories based on their driving frequency (i.e., daily commuter vs. weekend only drivers), and we used three well-known executive functioning tasks (the stop signal task, Iowa gambling task or IGT, and a task-switching test) to see whether scores on these tasks predicted such driving performances and behaviors such as braking time, lane-keeping, speed limit violations, and inter-vehicle distance (e.g., in a driving simulator). Participants went through a follow-lead-car scenario in the driving simulator for 20minutes and then completed the three executive tasks. We found that stop signal reaction time (SSRT) best predicted driving performance, and remained predictive against driver distraction, as well as variabilities in driving frequency. The IGT predicted speed limit violations in high-frequency drivers, whereas task-switching cost predicted lane keeping performance in low-frequency drivers. Together, these results highlight the importance of driving frequency when considering correlates between executive functions and driving performance and behavior. They also imply that executive tasks better predict driving performance in low-frequency (or inexperienced) drivers, while driver temperament (i.e., impulsiveness as indicated by IGT) better predicted driving performance in high-frequency (or experienced) drivers.

Response inhibition of children with ADHD in the stop-signal task: An event-related potential study