Cognitive Load Differentially Impacts Response Control in Girls and Boys with ADHD

Psychometric Properties and Adaptation of the Parent-Report Version of the Barkley Deficits in Executive Functioning Short-Form Scale in Spanish Children

INTRODUCTION

Executive functioning (EF) encompasses essential cognitive abilities crucial for self-regulation and goal achievement. The Barkley Deficits in Executive Functioning Scale in Children and Adolescents (BDEFS-CA) is a widely utilized tool for assessing EF in youth, with the short-form parent-reported version comprising twenty items.

OBJECTIVE

This study aims to assess the psychometric properties of the Spanish version of the BDEFS-CA Short-Form in children, including factor structure, reliability, validity, and sex invariance.

METHOD

Following transcultural adaptation by bilingual experts, the Spanish version was administered to 377 parents of children aged 6-12. Convergent validity was assessed using the Childhood Executive Functioning Inventory (CHEXI).

RESULTS

Results from confirmatory factor analysis supported a bifactor model encompassing a general EF factor and specific subscales (Comparative Fit Index = 0.984; Root-Mean-Square Error of Approximation = 0.048; Standardized Root Mean Square Residual = 0.024): time management (TM), problem solving/organization (PS), inhibition (IN), motivation (MOT), and emotional regulation (ER). High internal consistency was observed for both the general EF factor (α/ω = 0.956) and its subscales (TM: α/ω > 0.89, PS: α/ω > 0.93, IN: α/ω > 0.94, MOT: α/ω > 0.91, ER: α/ω > 0.93). Convergent validity was confirmed through strong correlations between BDEFS-CA and CHEXI scores (r = 0.552-0.892, P < 0.001). Sex invariance analysis revealed similar factor structures for men and women.

CONCLUSIONS

The Spanish adaptation of the BDEFS-CA Short-Form demonstrates strong psychometric properties, making it a reliable tool for assessing EF in Spanish-speaking children. Its simplicity and suitability suggest potential use by adults for gathering children's information.

Reconfiguration of Functional Brain Network Organization and Dynamics With Changing Cognitive Demands in Children With Attention-Deficit/Hyperactivity Disorder

BACKGROUND

The pathophysiology of attention-deficit/hyperactivity disorder (ADHD) is characterized by atypical brain network organization and dynamics. Although functional brain networks adaptively reconfigure across cognitive contexts, previous studies have largely focused on network dysfunction during the resting state. In this preliminary study, we examined how functional brain network organization and dynamics flexibly reconfigure across rest and 2 cognitive control tasks with different cognitive demands in 30 children with ADHD and 36 typically developing children (ages 8-12 years).

METHODS

We leveraged graph theoretical analyses to interrogate the segregation (modularity, within-module degree) and integration (global efficiency, node dissociation index) of frontoparietal, cingulo-opercular/salience, default mode, somatomotor, and visual networks. We also conducted edge time series analyses to quantify connectivity dynamics within and between these networks.

RESULTS

Across resting and task-based states, children with ADHD demonstrated significantly lower whole-graph modularity and a greater node dissociation index between default mode and visual networks. Furthermore, a significant task-by-diagnosis interaction was observed for frontoparietal network within-module degree, which decreased from rest to task in children with ADHD but increased in typically developing children. Finally, children with ADHD displayed significantly more dynamic connectivity within and across cingulo-opercular/salience, default mode, and somatomotor networks, especially during task performance. Exploratory analyses revealed associations between network dynamics, cognitive performance, and ADHD symptoms.

CONCLUSIONS

By integrating static and dynamic network analyses across changing cognitive demands, this study provides novel insight into how context-specific, context-general, and timescale-dependent network connectivity is altered in children with ADHD. Our findings highlight the involvement and clinical relevance of both association and sensory/motor systems in ADHD.

A systematic review and meta-analysis comparing the severity of core symptoms of attention-deficit hyperactivity disorder in females and males

In the past decade, there have been substantial changes in diagnostic nomenclature. This study investigated sex differences in attention-deficit/hyperactivity disorder (ADHD) symptom severity based on Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV, DSM-IV(TR), and DSM-5 criteria, separating rating scale and clinical interview data in children and adults with ADHD. PubMed, PsycINFO, and Scopus were searched for published studies (1996-2021) reporting severity of attention, and hyperactivity/impulsivity in males and females. We compared data: (1) across the entire lifespan aggregating rating scale and clinical interview data (51 studies), (2) drawing solely on rating scale data (18 studies), and (3) drawing solely on clinical interview data (33 studies). Fifty-two studies met inclusion criteria comparing data for females (n = 8423) and males (n = 9985) with ADHD across childhood and/or adulthood. In total, 15 meta-analyses were conducted. Pooled data across the lifespan aggregating both rating scale and clinical diagnostic interview data, showed males had significantly more severe hyperactivity/impulsivity symptoms than females. Rating scale data were similar; boys had significantly more severe hyperactivity/impulsivity than girls. In adulthood, men were rated to have significantly more severe inattention than women with no difference in the hyperactivity/impulsivity dimension. All significant differences were of small effect size. No significant sex differences in the severity of symptoms emerged for clinical interview data for children or adults, in contrast. Possible reasons for the discrepancy in findings between rating scales and clinical diagnostic interviews are discussed.

Validity of specific CPT indices in differentiating school-aged children previously diagnosed with attention deficit/hyperactivity disorder from school-aged children with non-attention deficit/hyperactivity disorder in general education classrooms: a case control study

BACKGROUND

Continuous performance tests (CPTs) are a popular tool for evaluating the symptoms of attention-deficit/hyperactivity disorder (ADHD). Performance measurements are typically linked to the biological features and cognitive functions of individuals. To determine the validity of specific CPT indices in differentiating between school-aged children with ADHD from with non-ADHD, each student's sex, chronological age, and cognitive abilities should be considered.

METHODS

In this prospective case-control study, a total of 30 non-ADHD students and 26 with ADHD who were aged 6 to 12 years were from general education classrooms. All students completed the Continuous Performance Tests (CPTs) and the Peabody Picture Vocabulary Test-revised (Mandarin-Chinese version). Demographic data were collected from the students' parents.

RESULTS

Detectability, Omissions, Commissions, and Hit Reaction Time Standard Deviation (HRT SD) yielded higher T-scores in children with ADHD than those without. Compared with non-ADHD students, those with ADHD had higher classification scores for Detectability, Omissions, Perseverations, and HRT SD. For each CPT index, after individual factors were controlled for, logistic regression revealed that only students with positive scores for Detectability, Omission, and HRT SD (adjusted odds ratios = 4.627, 9.977, and 3.908, Ps < 0.05) were likely to receive a diagnosis of ADHD. Furthermore, after individual characteristics were controlled for, Logistic regression also revealed that the cumulative positive scores of the Detectability, Omission, or and HRT SD remained associated with an increased risk of ADHD (adjusted odds ratio = 3.116, P < 0.01).

CONCLUSIONS

Compared with school-aged children with non-ADHD in general education classrooms, those with ADHD exhibited significantly lower performance in inattention-related CPT indices. To reach an accurate diagnosis through CPTs, clinicians should pay attention to Detectability, Omission, and HRT SD. Compared with other CPT indices, Detectability, Omission, and HRT SD may function as more suitable indicators for distinguishing between school-aged children with and non-ADHD in general education classrooms. These indicators are robust and unobscured by individual characteristics.

The Impact of Sex on Cognitive Control in ADHD: Girls Slow to Inhibit, Boys Inhibit Less, and Both Show Higher Response Variability

OBJECTIVE

To determine whether girls and boys with ADHD show distinct impairments in components of cognitive control across multiple tasks (go/no-go, stop signal, and flanker) and performance metrics (response speed, variability, and errors).

METHOD

A total of 300 children, ages 8 to 12 years with ADHD (n = 210, 58 girls) or typically developing (TD; n = 99, 37 girls), completed all tasks. Traditional response measures (e.g., mean and standard deviation of reaction time, inhibition errors, and stop signal reaction time) and ex-Gaussian modeling of reaction times (mu, sigma, and tau) were analyzed.

RESULTS

Girls showed intact response inhibition in the context of slower response speed, while boys made more inhibition errors and did not slow their response speed. Both girls and boys with ADHD showed higher response variability and poorer interference control than TD children.

CONCLUSION

Girls and boys with ADHD show distinct impairments in cognitive control that may be important for understanding the pathophysiology of ADHD.

Differences in Ex-Gaussian Parameters from Response Time Distributions Between Individuals with and Without Attention Deficit/Hyperactivity Disorder: A Meta-analysis

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent neurodevelopmental disorders in childhood and adolescence. Differences in reaction times (RT) in cognitive tasks have been consistently observed between ADHD and typical participants. Instead of estimating means and standard deviations, fitting non-symmetrical distributions like the ex-Gaussian, characterized by three parameters (µ, σ, and τ), account for the whole RT distributions. A meta-analysis is performed with all the available literature using ex-Gaussian distributions for comparisons between individuals with ADHD and controls. Results show that τ and σ are generally greater for ADHD samples, while µ tends to be larger for typical groups but only for younger ages. Differences in τ are also moderated by ADHD subtypes. τ and σ show, respectively, quadratic and linear relationships with inter-stimulus intervals from Continuous Performance Test and Go/No Go tasks. Furthermore, tasks and cognitive domains influence the three parameters. Interpretations of ex-Gaussian parameters and clinical implications of these findings are also discussed. Fitting ex-Gaussian distributions to RT data is a useful way to explore differences between individuals with ADHD and healthy controls.

Disentangling the relationships between motor control and cognitive control in young children with symptoms of ADHD

Children with ADHD experience difficulties with motor and cognitive control. However, the relationships between these symptoms are poorly understood. As a step toward improving treatment, this study investigated associations between specific aspects of motor control and cognitive control in children with varying levels of hyperactive-impulsive symptoms. A heterogeneous sample of 255 children of 4 to 10 years of age (median = 6.50, MAD = 1.36) completed a battery of tests probing motor generation, visuomotor fluency, visuomotor flexibility, cognitive inhibition, verbal and visuospatial working memory, and cognitive flexibility. Their caregivers were interviewed regarding their hyperactive-impulsive symptoms. 25.9% of the main sample met diagnostic criteria for ADHD. Multiple linear regression analysis was used to determine whether specific aspects of motor control were associated with specific aspects of cognitive control, and whether any associations were moderated by hyperactive-impulsive symptoms. Additionally, cognitive modeling (the drift diffusion model approximated with EZ-DM) was used to understand performance on a cognitive inhibition task. Visuomotor fluency was significantly associated with cognitive inhibition. Visuomotor flexibility was significantly associated with cognitive flexibility. There were no significant moderation effects. Cognitive modeling was inconclusive. In conclusion, the ability to fluently perform visually guided continuous movement is linked with the ability to inhibit the effects of distracting information. The ability to spontaneously use visual information to flexibly alter motor responses is related to the ability to cognitively shift from one frame of mind to another. These relationships appear to be quantitatively and qualitatively similar across the childhood hyperactive-impulsive continuum as rated by parents.

ADHD-related sex differences in frontal lobe white matter microstructure and associations with response control under conditions of varying cognitive load and motivational contingencies

Children with attention-deficit/hyperactivity disorder (ADHD) demonstrate reduced response inhibition, increased response time variability, and atypical frontal lobe white matter microstructure with emerging evidence of sex differences. This study aims to examine whether frontal lobe white matter microstructure is differentially impacted in ADHD by sex and whether this relates to Go/No-Go (GNG) task performance. Diffusion tensor imaging (DTI) from 187 children (8-12 years), including ADHD (n = 94) and typically developing controls (TD; n = 93). Participants completed three GNG tasks with varying cognitive demands and incentives (standard, cognitive, and motivational). Fractional anisotropy (FA) was examined as an index of white matter microstructure within bilateral frontal lobe regions of interest. Children with ADHD showed reduced FA in primary motor (M1) and supplementary motor area (SMA) regardless of sex. Sex-based dissociation for the effect of diagnosis was observed in medial orbitofrontal cortex (mOFC), with higher FA in girls with ADHD and lower FA in boys with ADHD. Both diagnosis and sex contributed to performance on measures of response inhibition and reaction time (RT) variability, with all children with ADHD demonstrating poorer performance on all GNG tasks, but boys with ADHD demonstrating more impulsivity on standard and motivational behavioral paradigms compared to girls with ADHD. Analyses revealed associations between reduced FA in M1, SMA, and mOFC and increased response inhibition and RT variability with some sex-based differences. These findings provide novel insights regarding the brain basis of ADHD and associated impairments in response inhibition and RT variability, and contribute to our understanding of sexual dimorphic behavioral outcomes.

Gender Differences in the Wechsler Intelligence Scale for Children in a Large Group of Italian Children with Attention Deficit Hyperactivity Disorder

Despite being repeatedly investigated in children with typical development, research on gender differences in intellectual abilities in specific groups of children, including children with attention deficit hyperactivity disorder (ADHD), has been scarce. In this paper, we evaluated the performance of a large group of Italian children with ADHD using the WISC-IV. We aimed at investigating the presence of gender differences using a multi-group confirmatory factor analysis approach. Results showed that the WISC is largely gender-invariant. However, some tasks present non-invariant patterns (block design and coding). Differences at the latent level also showed some differences (favoring boys) in the verbal comprehension index. Conversely, differences at the latent level were not found in the full-scale IQ or in the other main indices. These results have theoretical and practical implications.

A transdiagnostic view on MDD and ADHD: shared cognitive characteristics?

BACKGROUND

Major Depressive disorder (MDD) and Attention Deficit Hyperactivity Disorder (ADHD) are prevalent mental disorders that often co-occur. There is overlap in symptomatology between MDD and ADHD that complicates diagnostics and treatment selection. Hence, to aid diagnostics of single and comorbid disorders, we aimed to examine the discriminative power of common symptom measures and cognitive dysfunction to differentiate between participants diagnosed with MDD, ADHD, ADHD and comorbid MDD and without a mental disorder.

METHODS

Four diagnosed groups were compared: MDD (n = 103), ADHD (n = 78), comorbid MDD + ADHD (n = 29), healthy controls (HC; n = 123). We examined between-group differences and discriminative functions of clinically validated self-report symptom questionnaires, as well as task-based and self-report measures of cognitive dysfunction.

RESULTS

Based on the between group comparisons, all patient groups were characterized by clinically relevant levels of ADHD-symptomatology, executive dysfunction, and diminished cognitive performances in the domain of attention; even the MDD-only group. In addition, based on self-reported symptoms of MDD, ADHD, and executive dysfunction, discriminant function analysis classified all HC correctly (100%) and patients diagnosed with ADHD or MDD relatively well (resp. 85% and 82%). Comorbid MDD + ADHD was poorly differentiated from single MDD or ADHD by the commonly used self-report symptom questionnaires for MDD and ADHD (0% correct predictions), which substantially improved by incorporating the questionnaire on executive functioning (42% correct predictions).

CONCLUSIONS

In both MDD and ADHD, clinical levels of attentional and executive dysfunction were found, while these clinical groups differed in cognitive flexibility, initiating, inhibition and meta-cognition. Comorbid MDD + ADHD was poorly distinguishable from non-comorbid MDD and ADHD based on self-reported symptoms of depression and ADHD. Addition of subjective executive function in the discrimination models resulted in increased discriminative power. Our findings indicate that executive functioning measure can improve the diagnostic process of ADHD and MDD.

Sex differences in atypical fronto-subcortical structural connectivity among children with attention-deficit/hyperactivity disorder: Associations with delay discounting

PURPOSE

Atypical fronto-subcortical neural circuitry has been implicated in the pathophysiology of attention-deficit/hyperactivity disorder (ADHD), including connections between prefrontal cortical regions involved in top-down cognitive control and subcortical limbic structures (striatum and amygdala) involved in bottom-up reward and emotional processing. The integrity of fronto-subcortical connections may also relate to interindividual variability in delay discounting, or a preference for smaller, immediate over larger, delayed rewards, which is associated with ADHD, with recent evidence of ADHD-related sex differences.

METHODS

We applied diffusion tensor imaging to compare the integrity of the white matter connections within fronto-subcortical tracts among 187 8-12 year-old children either with ADHD ((n = 106; 29 girls) or typically developing (TD) controls ((n = 81; 28 girls). Analyses focused on diagnostic group differences in fractional anisotropy (FA) within fronto-subcortical circuitry implicated in delay discounting, connecting subregions of the striatum (dorsal executive and ventral limbic areas) and amygdala with prefrontal regions of interest (dorsolateral [dlPFC], orbitofrontal [OFC] and anterior cingulate cortex [ACC]), and associations with two behavioral assessments of delay discounting.

RESULTS

Children with ADHD showed reduced FA in tracts connecting OFC with ventral striatum, regardless of sex, whereas reduced FA in the OFC-amygdala and ventral ACC-amygdala tracts were specific to boys with ADHD. Across diagnostic groups and sex, reduced FA in the dorsal ACC-executive striatum tract correlated with greater game time delay discounting.

CONCLUSIONS

These results suggest a potential neurobiological substrate of heightened delay discounting in children with ADHD and support the need for additional studies including larger sample sizes of girls with ADHD to further elucidate ADHD-related sex differences in these relationships.

Gait in children with and without ADHD: A systematic literature review

BACKGROUND

There is increasing speculation whether Attention-Deficit/Hyperactivity Disorder (ADHD) has phenotypic or secondary motor symptoms. Some evidence suggests even fundamental motor skills such as walking can differ in ADHD, however, the evidence is limited and has not been reviewed. Therefore, we conducted a systematic review to summarize the findings regarding gait in ADHD compared to typically developing children in (1) normal (i.e., self-paced), (2) paced or complex (i.e., walking backwards), and (3) dual-task contexts.

METHOD

Following a thorough literature search and application of stringent exclusion criteria, a total of 12 studies were included in this review. All studies examined normal walking with a variety of gait parameters in children (age range: 5-18), however, selected parameters and group differences were often inconsistent.

RESULTS

In self-paced walking, studies reporting gait with coefficients of variance (CVs) indicated several between-group differences, whereas averages of gait variables were the same for those with ADHD and typically developing children. Paced or complex walking contexts often differed between ADHD and typically developing groups, favoring the ADHD group in some cases, but primarily the typically developing participants. Finally, walking contexts with dual-tasks showed more frequent performance losses in the ADHD group.

DISCUSSION

Children with ADHD seem to have specific patterns of gait variability compared to typically developing children, particularly in complex walking contexts and at faster paces. The influence of age, medication, and method of gait normalization may have influenced the results of studies. Overall, this review highlights the potential for a unique gait profile in children with ADHD.

Which Measures From a Sustained Attention Task Best Predict ADHD Group Membership?

Difficulty with sustaining attention to a task is a hallmark of ADHD. It would be useful to know which measures of sustained attention best predict a diagnosis of ADHD. Participants were 129 children with a diagnosis of ADHD and 129 matched controls who completed the fixed Sustained Attention to Response Task (SART). The number of commission and omission errors, standard deviation of response time (SDRT), tau, fast and slow frequency variability, d-prime, and mu were able to successfully classify children with and without ADHD. The mean response time, criterion, and sigma were not able to classify participants. The best classifiers were d-prime (0.75 Area Under the Receiver Operated Characteristic), tau (.74), SDRT (0.74), omission errors (0.72), commission errors (0.71), and SFAUS (0.70). This list of the best classifier measures derived from the SART may prove useful for the planning of future studies.

Reduced Error Recognition Explains Post-Error Slowing Differences among Children with Attention Deficit Hyperactivity Disorder

OBJECTIVE

Youth with attention deficit hyperactivity disorder (ADHD) often show reduced post-error slowing (PES) compared to typically developing controls. This finding has been interpreted as evidence that children with ADHD have error recognition and adaptive control impairments. However, several studies report mixed results regarding PES differences in ADHD, and among healthy controls, there is considerable debate about the cognitive-behavioral origin of PES.

METHODS

We tested competing hypotheses aimed at clarifying whether reduced PES in children with ADHD is due to impaired error detection, deficits in adaptive control, and/or attention orienting to novelty. Children aged 7-11 years with a diagnosis of ADHD (n = 74) and controls (n = 30) completed four laboratory-based computer tasks with variable cognitive loads and error types.

RESULTS

ADHD diagnosis was associated with shorter PES only on a task with high cognitive load and low error-cuing, consistent with impaired error recognition. In contrast, there was no evidence of impaired adaptive control or heightened novelty orienting among children with ADHD.

CONCLUSIONS

The cognitive-behavioral origin of PES is multifactorial, but reduced PES among children with an ADHD diagnosis is due to impaired error recognition during cognitively demanding tasks. Behavioral interventions that scaffold error recognition may facilitate improved performance among children with ADHD.

Frontal corticostriatal functional connectivity reveals task positive and negative network dysregulation in relation to ADHD, sex, and inhibitory control

Frontal corticostriatal circuits (FCSC) are involved in self-regulation of cognition, emotion, and motor function. While these circuits are implicated in attention-deficit/hyperactivity disorder (ADHD), the literature establishing FCSC associations with ADHD is inconsistent. This may be due to study variability in considerations of how fMRI motion regression was handled between groups, or study specific differences in age, sex, or the striatal subregions under investigation. Given the importance of these domains in ADHD it is crucial to consider the complex interactions of age, sex, striatal subregions and FCSC in ADHD presentation and diagnosis. In this large-scale study of 362 8-12 year-old children with ADHD (n = 165) and typically developing (TD; n = 197) children, we investigate associations between FCSC with ADHD diagnosis and symptoms, sex, and go/no-go (GNG) task performance. Results include: (1) increased striatal connectivity with age across striatal subregions with most of the frontal cortex, (2) increased frontal-limbic striatum connectivity among boys with ADHD only, mostly in default mode network (DMN) regions not associated with age, and (3) increased frontal-motor striatum connectivity to regions of the DMN were associated with greater parent-rated inattention problems, particularly among the ADHD group. Although diagnostic group differences were no longer significant when strictly controlling for head motion, with motion possibly reflecting the phenotypic variance of ADHD itself, the spatial distribution of all symptom, age, sex, and other ADHD group effects were nearly identical to the initial results. These results demonstrate differential associations of FCSC between striatal subregions with the DMN and FPN in relation to age, ADHD, sex, and inhibitory control.

Clinical characteristics, neuroimaging findings, and neuropsychological functioning in attention-deficit hyperactivity disorder: Sex differences

Recent clinical studies, in both children/adolescents and adults, have shown the extreme neuropsychological heterogeneity of attention-deficit hyperactivity disorder (ADHD): specific neuropsychological deficits have been found only in a minority of individuals, with no direct correlation between discrete cognitive performances and the trajectory of clinical symptoms. Deficits in specific neuropsychological functions may be common in ADHD, but nevertheless no cognitive or neuropsychological profile may fully explain the disorder. Sex differences in the ADHD presentation, both at a neuropsychological and clinical level, also contribute to this clinical and neuropsychological heterogeneity. At a neuropsychological level, females with ADHD may show greater working memory problems, poorer vocabulary skills and worse visual spatial reasoning. Structural and functional imaging study also show discrete differences across sex; however, the great majority of clinical studies mainly or exclusively include male participants with insufficient data to draw firm conclusions on sex differences within the disorder. Here, we report the recent literature data, discussing still open research questions about the clinical presentation, neuroimaging findings, and neuropsychological functioning in ADHD with a focus on the impact of sex differences-a deeper insight in these unresolved issues may have relevant clinical and therapeutic implications for tailored, effective, and long-lasting interventions.

Inhibitory abilities in girls and boys: More similarities or differences?

This brief review examined the literature from 1990 to June 2020 on sex differences in inhibitory abilities from early childhood to adolescence, primarily in individuals with typical development (TD) and individuals with atypical development. The 38 articles included (28 on individuals with TD, eight on the attention deficit hyperactivity disorder [ADHD] population, and two on individuals with autism spectrum disorder [ASD]) suggest that the cognitive demand of the task is important, together with contextual factors that may interact with the development of inhibitory ability, for revealing differences between the sexes. The literature has neglected the multicomponential nature of inhibitory abilities, and the emphasis has consequently been placed on response inhibition (vs. other components). The implication of the impurity problem has also been considered. The findings on children and adolescents with ADHD or ASD-even for outcomes that are not conclusive-imply that there is no evidence for a difference in inhibitory abilities between males and females. The literature proposes an asynchrony in the development of inhibitory abilities that may explain what is found in typically developing girls who perform more highly than boys on more demanding tasks.

Beyond Massive Univariate Tests: Covariance Regression Reveals Complex Patterns of Functional Connectivity Related to Attention-Deficit/Hyperactivity Disorder, Age, Sex, and Response Control

Background

Studies of brain functional connectivity (FC) typically involve massive univariate tests, performing statistical analysis on each individual connection. In this study, we apply a novel whole-matrix regression approach referred to as covariate assisted principal regression to identify resting-state FC brain networks associated with attention-deficit/hyperactivity disorder (ADHD) and response control.

Methods

Participants included 8- to 12-year-old children with ADHD (n = 115; 29 girls) and typically developing control children (n = 102; 35 girls) who completed a resting-state functional magnetic resonance imaging scan and a Go/NoGo task. We modeled three sets of covariates to identify resting-state networks associated with an ADHD diagnosis, sex, and response inhibition (commission errors) and variability (ex-Gaussian parameter tau).

Results

The first network includes FC between striatal-cognitive control (CC) network subregions and thalamic-default mode network (DMN) subregions and is positively related to age. The second consists of FC between CC-visual-somatomotor regions and between CC-DMN subregions and is positively associated with response variability in boys with ADHD. The third consists of FC within the DMN and between DMN-CC-visual regions and differs between boys with and without ADHD. The fourth consists of FC between visual-somatomotor regions and between visual-DMN regions and differs between girls and boys with ADHD and is associated with response inhibition and variability in boys with ADHD. Unique networks were also identified in each of the three models, suggesting some specificity to the covariates of interest.

Conclusions

These findings demonstrate the utility of our novel covariance regression approach to studying functional brain networks relevant for development, behavior, and psychopathology.

Meta-Analysis of Sex Differences in ADHD Symptoms and Associated Cognitive Deficits

Objective: A meta-analysis was carried out to determine whether there are sex differences among children and adolescents with ADHD on the primary symptoms of ADHD and on executive and attentional functioning. Method: Studies published from 1997 to 2017 comparing boys and girls with a valid ADHD diagnosis were retained. Results: The meta-analysis found boys with ADHD to be more hyperactive than girls with ADHD and boys to have more difficulties in terms of motor response inhibition and cognitive flexibility. Results also confirm that youths with ADHD have more executive deficits than non-ADHD peers have, but there is no sex difference in this regard. Conclusion: Results show that there are sex differences in the behavioral expression of the difficulties related to ADHD. This highlights the importance of pursuing research to refine the profile of girls with ADHD and to develop diagnostic criteria adapted to each sex.

Event-Based Prospective Memory Deficit in Children with ADHD: Underlying Cognitive Factors and Association with Symptoms

Event-based prospective memory (PM) was investigated in children with Attention deficit/hyperactivity disorder (ADHD), using a novel experimental procedure to evaluate the role of working memory (WM) load, attentional focus, and reward sensitivity. The study included 24 children with ADHD and 23 typically-developing controls. The experimental paradigm comprised one baseline condition (BC), only including an ongoing task, and four PM conditions, varying for targets: 1 Target (1T), 4 Targets (4T), Unfocal (UN), and Reward (RE). Children with ADHD were slower than controls on all PM tasks and less accurate on both ongoing and PM tasks on the 4T and UN conditions. Within the ADHD group, the accuracy in the RE condition did not differ from BC. A significant relationship between ADHD-related symptoms and reduced accuracy/higher speed in PM conditions (PM and ongoing trials), but not in BC, was detected. Our data provide insight on the adverse role of WM load and attentional focus and the positive influence of reward in the PM performance of children with ADHD. Moreover, the relation between PM and ADHD symptoms paves the road for PM as a promising neuropsychological marker for ADHD diagnosis and intervention.

Distinct Patterns of Impaired Cognitive Control Among Boys and Girls with ADHD Across Development

This study examined whether girls and boys with ADHD show similar impairments in cognitive control from childhood into adolescence and the developmental relationship between cognitive control and ADHD symptoms. Participants include 8-17-year-old children with ADHD (n = 353, 104 girls) and typically developing (TD) controls (n = 241, 86 girls) with longitudinal data obtained from n = 137. Participants completed two go/no-go (GNG) tasks that varied in working memory demand. Linear mixed-effects models were applied to compare age-related changes in cognitive control for each GNG task among girls and boys with ADHD and TD controls and in relation to ADHD symptoms. Boys with ADHD showed impaired response inhibition and increased response variability across tasks. In contrast, girls with ADHD showed impaired response inhibition only with greater working memory demands whereas they displayed increased response variability regardless of working memory demands. Analysis of age-related change revealed that deficits in cognitive control under minimal working memory demands increase with age among girls with ADHD and decrease with age among boys with ADHD. In contrast, deficits in cognitive control with greater working memory demands decrease with age among both boys and girls with ADHD compared to TD peers. Among children with ADHD poor response inhibition during childhood predicted inattentive symptoms in adolescence and was associated with less age-related improvement in inattentive symptoms. These findings suggest that girls and boys with ADHD show differential impairment in cognitive control across development and response inhibition in childhood may be an important predictor of ADHD symptoms in adolescence.

Response Inhibition, Response Execution, and Emotion Regulation among Children with Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is associated with deficits in response inhibition, response execution, and emotion regulation. However, the nature of the associations among these deficits remains unclear. Thus, this study examines these associations using a multi-method design. One hundred sixty-six children (aged 5-13 years; 66.3% male; 75 with ADHD) completed two conditions (i.e., neutral and fear) of an emotional go/no-go task. Parasympathetic-based regulation was indexed via respiratory sinus arrhythmia (RSA), and sympathetic-based reactivity was indexed via cardiac pre-ejection period (PEP). Overall, children exhibited more difficulty with response execution (i.e., more omission errors, fewer correct go responses) and less difficulty with response inhibition (i.e., fewer commission errors, more correct no-go responses) during the fear condition than the neutral condition. Children with ADHD displayed more difficulty with response execution during the fear condition compared to typically developing youth. Additionally, children with ADHD displayed parasympathetic-based dysregulation (i.e., RSA increase from baseline) and reduced sympathetic-based reactivity (i.e., PEP lengthening) compared to typically developing youth across task conditions. In sum, children with ADHD demonstrate greater difficulty with response execution during emotionally salient contexts, as well as parasympathetic-based emotion dysregulation. Future work should examine these associations longitudinally with the aim of predicting impairment and treatment response in youth with ADHD.

Response control correlates of anomalous basal ganglia morphology in boys, but not girls, with attention-deficit/hyperactivity disorder

Anomalous basal ganglia morphology may contribute to deficient motor response control in children with attention-deficit/hyperactivity disorder (ADHD). This study expands upon recent evidence of sex differences in subcortical morphology and motor response control deficits among children with ADHD to examine basal ganglia volume and shape in relation to motor response control. Participants included 8-12 year-old children with ADHD (n = 52, 21 girls) and typically developing (TD) controls (n = 45, 19 girls). High resolution T1-weighted 3D MPRAGE images covering the whole brain were acquired for all participants on a 3 T scanner. Participants performed two computer-based go/no-go tasks that differed in the extent to which working memory was necessary to guide response selection. Shape-based morphometric analyses were performed in addition to traditional volumetric comparisons and correlations with measures of motor response control were examined. Boys with ADHD consistently demonstrated increased commission error rate and response variability, regardless of task demands, suggesting broad response control deficits. In contrast, response control deficits among girls with ADHD varied depending on task demands and performance measures. Volumetric reductions and inward deformation (compression) on the dorsal surface of the globus pallidus and within subregions of the putamen receiving projections from limbic, executive and motor cortices were observed in boys, but not girls, with ADHD relative to TD children. Mediation analyses revealed that putamen and globus pallidus volumes mediated the relationship between diagnosis and commission error rate. Furthermore, reduced volumes of these structures and localized inward deformation within executive and motor circuits correlated with poorer response control, particularly under conditions of increased cognitive load. These findings suggest that anomalous basal ganglia morphology is related to impaired motor response control among boys with ADHD.

Development of the frontal lobe

Development of the frontal lobe is critical to acquisition, execution, and control of a wide range of functions, from basic motor response to complex decision-making. These functions are influenced by contingency-based (e.g., reward and response-cost/punishment) feedback that is mediated through the adaptive integration of fronto-subcortical neural circuitry. The frontal lobe manages incoming information and chooses the appropriate action based on one's goals in a particular context. This aspect of frontal function, while only one component, is crucial to development and maintenance of approach and avoidance behavior central to all human (and animal) behavior. Furthermore, disruptions in fronto-subcortical circuitry governing motivated behavior appear to contribute to a range of developmental disorders, including attention-deficit/hyperactivity disorder (ADHD), and confer vulnerability for psychopathology more broadly. The particular deficits that manifest in altered behavior depend upon the specific circuitry that is compromised due to the functional specificity of distinct regions of the frontal lobe and its interconnections with subcortical structures. Neurobiologic models of motivated behavior provide a valuable framework for characterizing developmental disorders from a transdiagnostic dimensional systems perspective. Improved characterization of approach and avoidance motivation across neurodevelopmental disorders has the potential to inform the development of novel interventions and personalized medicine.

ADHD-related sex differences in fronto-subcortical intrinsic functional connectivity and associations with delay discounting

Background

Attention-deficit/hyperactivity disorder (ADHD) is associated with atypical fronto-subcortical neural circuitry and heightened delay discounting, or a stronger preference for smaller, immediate rewards over larger, delayed rewards. Recent evidence of ADHD-related sex differences in brain structure and function suggests anomalies in fronto-subcortical circuitry may differ among girls and boys with ADHD. The current study examined whether the functional connectivity (FC) within fronto-subcortical neural circuitry differs among girls and boys with ADHD compared to same-sex typically developing (TD) controls and relates to delay discounting.

Methods

Participants include 8–12-year-old children with ADHD (n = 72, 20 girls) and TD controls (n = 75, 21 girls). Fronto-subcortical regions of interest were functionally defined by applying independent component analysis to resting-state fMRI data. Intrinsic FC between subcortical components, including the striatum and amygdala, and prefrontal components, including ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC), and anterior dorsolateral prefrontal cortex (dlPFC), was compared across diagnostic groups overall and within sex. Correlations between intrinsic FC of the six fronto-subcortical pairs and delay discounting were also examined.

Results

Both girls and boys with ADHD show atypical FC between vmPFC and subcortical regions including the striatum (stronger positive FC in ADHD) and amygdala (weaker negative FC in ADHD), with the greatest diagnostic effects among girls. In addition, girls with ADHD show atypical intrinsic FC between the striatum and dlPFC components, including stronger positive FC with ACC and stronger negative FC with dlPFC. Further, girls but not boys, with ADHD, show heightened real-time delay discounting. Brain–behavior correlations suggest (1) stronger negative FC between the striatal and dlPFC components correlated with greater money delay discounting across all participants and (2) stronger FC between the amygdala with both the dlPFC and ACC components was differentially related to heightened real-time discounting among girls and boys with and without ADHD.

Conclusions

Our findings suggest fronto-subcortical functional networks are affected in children with ADHD, particularly girls, and relate to delay discounting. These results also provide preliminary evidence of greater disruptions in fronto-subcortical FC among girls with ADHD that is not due to elevated inattention symptom severity, intellectual reasoning ability, age, or head motion.

Electronic supplementary material

The online version of this article (10.1186/s11689-018-9254-9) contains supplementary material, which is available to authorized users.

Greater delay discounting among girls, but not boys, with ADHD correlates with cognitive control

Cognitive neuroscience models suggest both reward valuation and cognitive control contribute to reward-based decision-making. The current study examined the relationship between cognitive control and delay discounting (i.e., choosing smaller, immediate over larger, delayed rewards) in a large sample of boys and girls diagnosed with attention-deficit/hyperactivity disorder (ADHD; N = 95) and typically developing control children (TD; N = 59). Specifically, we examined performance on multiple measures of cognitive control (i.e., Go/No-Go task, Stop Signal task, and Spatial Span task) and delay discounting (i.e., Classic Delay Discounting and Real-Time Delay Discounting tasks), as well as the relationship between these measures. Results indicated that sex moderated the effects of group on task performance. Specifically, girls with ADHD, but not boys with the disorder, exhibited atypical delay discounting of real-time rewards. Results from correlational analyses indicated that delay discounting and cognitive control were not significantly correlated in the overall sample. Multiple regression analyses demonstrated that among girls with ADHD poorer spatial working memory and inhibitory control predicted greater real-time discounting. Collectively, findings provide support for distinct patterns of cognitive control and delay discounting among school-aged girls and boys with ADHD. Additionally, findings suggest that among girls with ADHD, those who exhibit relatively poor working memory and inhibitory control might be a particularly vulnerable subgroup with the greatest propensity to exhibit maladaptive decision-making.

Investigating the Impact of Cognitive Load and Motivation on Response Control in Relation to Delay Discounting in Children with ADHD

Attention-deficit/hyperactivity disorder (ADHD) is characterized by deficits in impulse control across a range of behaviors, from simple actions to those involving complex decision-making (e.g., preference for smaller-sooner versus larger later rewards). This study investigated whether changes in motor response control with increased cognitive load and motivational contingencies are associated with decision-making in the form of delay discounting among 8-12 year old children with and without ADHD. Children with ADHD (n = 26; 8 girls) and typically developing controls (n = 40; 11 girls) completed a standard go/no-go (GNG) task, a GNG task with motivational contingencies, a GNG task with increased cognitive load, and two measures of delay discounting: a real-time task in which the delays and immediately consumable rewards are experienced in real-time, and a classic task involving choices about money at longer delays. Children with ADHD, particularly girls, exhibited greater delay discounting than controls during the real-time discounting task, whereas diagnostic groups did not significantly differ on the classic discounting task. The effect of cognitive load on response control was uniquely associated with greater discounting on the real-time task for children with ADHD, but not for control children. The effect of motivational contingencies on response control was not significantly associated with delay discounting for either diagnostic group. The findings from this study help to inform our understanding of the factors that influence deficient self-control in ADHD, suggesting that impairments in cognitive control may contribute to greater delay discounting in ADHD.

Is hyperactivity ubiquitous in ADHD or dependent on environmental demands? Evidence from meta-analysis

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 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.

Increased Delay Discounting on a Novel Real-Time Task among Girls, but not Boys, with ADHD

The aim of this study was to examine delay discounting in girls and boys with ADHD-Combined type (ADHD-C) relative to typically developing (TD) children on two tasks that differ in the extent to which the rewards and delays were experienced by participants. Children ages 8-12 years with ADHD-C (n=65; 19 girls) and TD controls (n=55; 15 girls) completed two delay discounting tasks involving a series of choices between smaller, immediate and larger, delayed rewards. The classic delay discounting task involved choices about money at delays of 1-90 days and only some of the outcomes were actually experienced by the participants. The novel real-time discounting task involved choices about an immediately consumable reward (playing a preferred game) at delays of 25-100 s, all of which were actually experienced by participants. Participants also provided subjective ratings of how much they liked playing the game and waiting to play. Girls with ADHD-C displayed greater delay discounting compared to boys with ADHD-C and TD girls and boys on the real-time discounting task. Diagnostic group differences were not evident on the classic discounting task. In addition, children with ADHD-C reported wanting to play the game more and liking waiting to play the game less than TD children. This novel demonstration of greater delay discounting among girls with ADHD-C on a discounting task in which the rewards are immediately consumable and the delays are experienced in real-time informs our understanding of sex differences and motivational processes in children with ADHD. (JINS, 2016, 22, 12-23).

Sex-Based Dissociation of White Matter Microstructure in Children With Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

Sexual dimorphism is evident in attention-deficit/hyperactivity disorder (ADHD), including subtype prevalence, adverse outcomes, and neural phenotype. Neurobiological studies of ADHD suggest that boys show more abnormalities in motor and premotor structure and function, whereas girls differ from typically developing (TD) peers in prefrontal circuitry. We applied diffusion tensor imaging (DTI) to identify ADHD-related sex-specific differences in motor/premotor and prefrontal white matter (WM) microstructure in children.

METHOD

DTI estimated differences in WM microstructure among 120 children 8 to 12 years of age, 60 with ADHD (30 boys and 30 girls) and 60 controls (30 boys and 30 girls), matched on age, IQ, and handedness. Effects of diagnosis and sex on fractional anisotropy (FA) were assessed in motor/premotor and prefrontal regions. Group differences in FA and associations with response control (e.g., reaction time variability [CVRT] and commission error rate) were examined separately within sex.

RESULTS

Sex-by-diagnosis interactions were observed for FA in primary motor (M1) and medial orbitofrontal (MOFC) cortex. Post hoc tests revealed that boys with ADHD showed bilateral reductions in FA within M1, compared with TD peers; in contrast, girls with ADHD showed higher FA bilaterally within MOFC. Decreased M1 FA was associated with higher CVRT in boys and higher commission error rates in girls. For MOFC, lower FA was associated with greater CVRT and commission error rates across all participants with ADHD.

CONCLUSION

ADHD affects the white matter of boys and girls differently; boys appear to be more affected in regions responsible for control of basic actions, whereas girls show more abnormalities in regions responsible for higher-level, top-down control.

Reduced intrasubject variability with reinforcement in boys, but not girls, with ADHD: Associations with prefrontal anatomy

This study examined the impact of motivational contingencies (reinforcement and punishment) on go/no-go (GNG) task performance in girls and boys with ADHD relative to typically developing (TD) children and associations with prefrontal anatomy. Children ages 8-12 with ADHD (n=107, 36 girls) and TD controls (n=95, 34 girls) completed a standard and a motivational GNG task and associations with prefrontal cortex (PFC) surface area were examined. Intrasubject variability (ISV) was lower during the motivational compared to the standard GNG among TD girls and boys, and boys with ADHD, but not among girls with ADHD. A greater reduction in ISV was associated with greater PFC surface area among children with ADHD. This novel demonstration of improvement in ISV with motivational contingencies for boys, but not girls, with ADHD and associations with PFC anatomy informs our understanding of sex differences and motivational factors contributing to ISV in children with ADHD.