Process examination of executive function in ADHD: sex and subtype effects

Effects of comorbidity on executive functions among children with ADHD, finding trends

There is still no basic overview about the effect of various types of comorbidity in executive functions due to two main reasons: (1) the type and number of comorbidities in ADHD is significantly varied, (2) EFs are very diverse and have different neuropsychological properties. Our objective was to determine the effect of comorbid disorders (number and type) on the performance in a wide range (seven) of executive functions in a sample of children with ADHD. Fifty-five male children aged seven to nine years with ADHD were divided into six groups: G1 = ADHD only (ADHD-O), G1 = Oppositional defiant disorder (ODD), G3 = (anxiety/depressive disorder (ADD), G4 = ODD + ADD, G5 = ODD + learning disorder (LD), G6 = ODD + LD + conduct disorder (CD). The six groups exhibited different number of deficits in EFs; G1 showed only 1 deficit in contrast, G6 presented 11. Statistical analysis (ANOVA and logistic regression) identified three most affected EFs: Working memory, generation/classification of semantic categories, and inhibitory control. Alterations in EFs increased mainly in relation to the increase of the specific number and type of comorbidity. To date, no studies have addressed comorbidity from this perspective. A wide range approach of EF confirms the need to further study comorbidity in ADHD from a wide range/variety perspective and determine all possible combinations (number/type) to clarify its contribution to the complex neuropsychology functioning in ADHD.

An examination of the effects of ADHD symptoms and sex on the relation between cannabis protective behavioral strategies and cannabis consequences

The risk for cannabis-related problems is elevated among young adults with attention-deficit/hyperactivity disorder (ADHD) symptoms. It is unknown whether the use of cannabis protective behavioral strategies (PBS) mitigates this risk for college students with ADHD. Prior research finds that college students who use alcohol and report high levels of ADHD symptoms particularly benefit from employing alcohol PBS, and these relations are strongest for male students. Thus, this study examined the moderating effects of ADHD symptoms and sex assigned at birth on the relation between cannabis PBS use and cannabis-related problems among college students who use cannabis. Participants were 384 college students (66.9% female, 57.8% white non-Hispanic, M_age = 19.29) from 12 United States universities who reported past-month cannabis use. Participants completed measures of demographics, ADHD symptoms, past-month cannabis frequency and related problems, and cannabis PBS use via an online survey. There was a significant interaction of ADHD hyperactive/impulsive symptoms, PBS use, and sex on cannabis-related problems, controlling for cannabis use frequency. The strength of the negative association between PBS use and problems depended on level of ADHD symptoms for females, but not for males. However, there were no interactive effects for ADHD inattentive symptoms. These results supplement the literature base on relations between PBS use and ADHD symptoms in college students, extending support for their use to cannabis users. Importantly, promoting PBS use to female college students who are high in hyperactive/impulsive ADHD symptoms is recommended.

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.

The relationship between executive function, processing speed, and attention-deficit hyperactivity disorder in middle childhood

Attention-Deficit Hyperactivity Disorder (ADHD) is a heterogeneous disorder that is highly impairing. Early, accurate diagnosis maximizes long-term positive outcomes for youth with ADHD. Tests of executive functioning (EF) are potential tools for screening and differential diagnosis of ADHD subtypes. However, previous research has been inconsistent regarding the specificity and magnitude of EF deficits across ADHD subtypes. Here, we advance knowledge of the EF-ADHD relationship by using: (1) dimensional latent factor models of ADHD that captures the heterogeneity of expression, and (2) a comprehensive, reliable battery of EF tasks and modeling relationships with a general factor of EF ability. We tested 1548 children and adolescents (ages 7-15 years) from the Texas Twin Project, a population-based cohort with a diverse socioeconomic and ethnic composition. We show that EF deficits were specific to the inattention domain of ADHD. Moreover, we found that the association between EF task performance and inattention was stable across sociodemographic groups. Our results demonstrate that failures of executive control are selectively manifested as covert inattentive symptoms, such as trouble with organization, forgetfulness, and distractedness, rather than overt symptoms, such as inappropriate talkativeness and interruption. Future research, utilizing a bifactor characterization of ADHD in clinical samples, is needed to further refine understanding of the nature of cognitive deficits in ADHD across the full range of symptom variation.

Gender differences in adult ADHD: Cognitive function assessed by the test of attentional performance

Introduction

The aim of this study was to assess cognitive differences between male and female adults with Attention Deficit Hyperactivity Disorder (ADHD).

Methods

Patients with an ADHD diagnosis according to the DSM-IV guidelines were included in a cross-sectional study evaluating cognitive measures. 28 women and 41 men from ages 19 to 56 completed self-report questionnaires and performed a computer-based test of attentional performance (TAP). The TAP assesses cognitive functions highly affected in ADHD patients, including working memory, alertness and attention as well as behavioral control and response inhibition.

Results

There were no measurable differences in self-report scales assessing current symptomology between the sexes, however men scored higher on the scale for childhood symptoms. Performance measures for general wakefulness were comparable between men and women, while working memory and behavioral control test results differed. Females reacted significantly slower and more unstable for both the TAP Go/NoGo paradigm and working memory subtest, while also making more errors in the latter.

Conclusions

We found gender-specific effects regarding working memory and behavioral control in this sample of adult patients with ADHD. Further studies are warranted, examining whether these differences relate to differences in clinical presentation and comorbidity patterns between men and women.

Executive Functions in Children with ADHD and/or Reading Difficulty

Abstract The objective of this study was to compare the Executive Functions performance (EFs: inhibitory control, auditory and visuospatial working memory, cognitive flexibility and verbal fluency) between children with ADHD, reading difficulties (RD), comorbidity ADHD/RD and without complaints of ADHD and RD (WRD). Participated 104 children, of both sexes, aged between eight and 11 years old. The results indicated worse performance of ADHD/RD group in the majority EFs. ADHD presented better performance than DL in semantic verbal fluency. The WRD obtained better scores than the ADHD / DL and DL in practically all the evaluated EFs, but did not differ of ADHD.

Parent versus teacher ratings on the BRIEF-preschool version in children with and without ADHD

Caregiver rating scales represent an important component of comprehensive child neuropsychological assessments for conditions such as Attention-deficit/Hyperactivity Disorder (ADHD); however, low inter-rater reliability (parent vs. teacher) often complicates interpretation. It has been challenging to identify the factors contributing to inter-rater variability, particularly when parents and teachers complete slightly different versions of the same rating scale. The present study examined the associations between parent- and teacher-reported executive functions in 84 children, ages 4-5 years, with and without symptoms of ADHD, using the Behavior Rating Inventory of Executive Function-Preschool (BRIEF-P). Use of the BRIEF-P allows for direct comparison of symptom ratings because parents and teachers complete the exact same measure. Significant associations between raters were observed on 4 of 5 BRIEF-P subscales when rating children with ADHD, but on only 1 subscale when rating typically developing (TD) children. The Shift scale in particular displayed low, non-significant inter-rater association in both groups. Significant group-by-rater interactions were observed for Working Memory and Plan/Organize scales, and driven by larger inter-rater T-score discrepancies in the TD group, such that teachers rated children as having more symptoms than parents. Conversely, examination of raw scores reflected no significant rater differences in the TD group, but significant or nearly significant differences on multiple scales in the ADHD group, such that parents rated more symptoms than teachers. Inter-rater associations for the BRIEF-P appear to vary based on who is being rated (i.e., children with or without ADHD), the specific subscales, and whether standardized or raw scores are analyzed.

Barkley Deficits in Executive Functioning Scale (BDEFS): Validation in a Large Multisite College Sample

Despite the importance of daily life executive functioning (EF) for college students' success, few measures exist that have been validated in college students specifically. This study examined the factor structure of the Barkley Deficits in Executive Functioning Scale (BDEFS) in college students. Participants were 1,311 students (ages 18-28 years, 65% female) from five universities in the United States. Additionally, the study examined invariance across sex, age, and attention-deficit/hyperactivity disorder symptoms. Exploratory structural equation modeling provided strong support for the BDEFS five-factor structure though some items had high cross-loadings on multiple factors. Findings generally supported invariance across sex and age; however, loadings, thresholds, and factor means differed based on attention-deficit/hyperactivity disorder symptoms. Stronger support for invariance across sex emerged for a reduced item version that eliminated cross-loading items. Overall, findings provide support for the validity and utility of the BDEFS in college students.

Comorbidity of reading disabilities and ADHD: Structural and functional brain characteristics

Reading disabilities (RD) and attention-deficit/hyperactivity disorder (ADHD) are two of the most common developmental disorders. RD and ADHD frequently co-occur, which raises questions about how the disorders interact and to what extent they can be differentiated. To date, the underlying neural mechanisms leading to RD-ADHD comorbidity (COM) are not understood. In this study, structural and functional magnetic resonance imaging (fMRI) were combined with comprehensive behavioral testing in order to characterize the behavior, brain structure, and neural correlates of executive function, phonological processing and reading fluency in 60 children with clinical diagnoses of RD, ADHD, or COM, and controls. Whole-brain analyses of variance were performed on cortical thickness values and on the data of the three fMRI tasks to investigate overall group differences. To validate these findings, a region of interest analysis was performed in regions that have previously been shown to exhibit group differences in children with RD or ADHD using the same paradigms. The neuroimaging results demonstrated structural and functional atypicalities for COM in regions that are frequently associated with deficits in children with isolated ADHD or RD. A combination of shared and distinctive brain alterations between the clinical groups was identified, supporting the multiple deficit model for ADHD, RD, and its comorbidity.

Planning Skills of Adolescents With ADHD

OBJECTIVE

This study assesses planning skills of adolescents with ADHD using a multi-method assessment and explores subtype differences between inattentive and combined subtypes.

METHOD

One hundred fifteen adolescents with ADHD and 34 typically developing controls completed subtests of the Delis-Kaplan Executive Function System (D-KEFS), Behavioral Assessment of the Dysexecutive Syndrome (BADS), and Behavior Rating Inventory of Executive Function (BRIEF).

RESULTS

No group differences were found on the D-KEFS. The BADS Zoo Map test showed longer completion times in the inattentive than in the combined subtype and controls. The BRIEF showed more planning problems in adolescents with ADHD (both subtypes) than in controls, with the combined subtype showing most problems on overall executive functioning.

CONCLUSION

Only a proportion of adolescents with ADHD shows planning deficits. To capture these planning problems in adolescents with ADHD, it seems important to use multiple measures of planning, both ratings and "less structured" neurocognitive measures of planning.

Prepotent response inhibition and reaction times in children with attention deficit/hyperactivity disorder from a Caribbean community

Impairment in inhibitory control has been postulated as an underlying hallmark of attention deficit/hyperactivity disorder (ADHD), which can be utilized as a quantitative trait for genetic studies. Here, we evaluate whether inhibitory control, measured by simple automatized prepotent response (PR) inhibition variables, is a robust discriminant function for the diagnosis of ADHD in children and can be used as an endophenotype for future genetic studies. One hundred fifty-two school children (30.9% female, 67.8% with ADHD) were recruited. The ADHD checklist was used as the screening tool, whilst the DSM-IV Mini International Neuropsychiatry Interview, neurologic interview and neurologic examination, and the WISC III FSIQ test were administered as the gold standard procedure to assert ADHD diagnosis. A Go/No-Go task using a naturalistic and automatized visual signal was administered. A linear multifactor model (MANOVA) was fitted to compare groups including ADHD status, age, and gender as multiple independent factors. Linear discriminant analysis and the receiver operating characteristic curve were used to assess the predictive performance of PR inhibition variables for ADHD diagnosis. We found that four variables of prepotent response reaction time- and prepotent response inhibition established statistically significant differences between children with and without ADHD. Furthermore, these variables generated a strong discriminant function with a total classification capability of 73, 84% specificity, 68% sensitivity, and 90% positive predictive value for ADHD diagnosis, which support reaction times as a candidate endophenotype that could potentially be used in future ADHD genetic research.

Disruptive behavior disorders and indicators of disinhibition in adolescents: The BRIEF-SR, anti-saccade task, and D-KEFS color-word interference test

Disinhibition contributes to the development of disruptive behavior disorders (DBD) in adolescents. Self-reports and behavioral tasks are commonly used to assess disinhibition, each with their unique strengths and limitations. Accordingly, it is important to identify which measure, or combination thereof, is the most effective in predicting DBD symptoms. This study assessed the relationship between DBD (symptoms of ADHD/ODD/CD) and two behavioral disinhibition tasks: the anti-saccade task and the D-KEFS color-word interference test, as well as a self-report measure (the BRIEF-SR). The results indicated that the BRIEF-Inhibit scale accounted for the majority of the variance in the DBD sum score. The anti-saccade task and color-word interference test were also significantly associated with an increase in the number of DBD symptoms endorsed. These behavioral tasks accounted for 9% additional variance than the self-report alone. Therefore, combining self-report measures with behavioral disinhibition tasks may provide the most thorough assessment of adolescent DBD.

Sex Differences in Attentional Performance in a Clinical Sample With ADHD of the Combined Subtype

OBJECTIVE

The goal of the present study was to assess whether girls with ADHD express similar deficits in various attention tasks to those described in boys.

METHOD

A total of 175 children with the combined subtype of ADHD (89 females) and 132 normal controls (60 females) aged 8 to 14 years participated. Five different tests were conducted: alertness, sustained attention, focused attention, divided attention, and a set-shifting task.

RESULTS

The children with ADHD performed worse on all aspects of attention compared with healthy control participants. Several overall general sex differences could be detected, with boys exhibiting faster reaction times and greater response variability. Controlling for ADHD symptom severity and psychiatric comorbidities, no Sex × Diagnosis interaction was found, suggesting that males and females with ADHD experience comparable attentional deficits.

CONCLUSION

These results indicate that deficits in various attentional domains are a robust component of ADHD in males and females.

Distinct frontal lobe morphology in girls and boys with ADHD

OBJECTIVE

This study investigated whether frontal lobe cortical morphology differs for boys and girls with ADHD (ages 8-12 years) in comparison to typically developing (TD) peers.

METHOD

Participants included 226 children between the ages of 8-12 including 93 children with ADHD (29 girls) and 133 TD children (42 girls) for which 3T MPRAGE MRI scans were obtained. A fully automated frontal lobe atlas was used to generate functionally distinct frontal subdivisions, with surface area (SA) and cortical thickness (CT) assessed in each region. Analyses focused on overall diagnostic differences as well as examinations of the effect of diagnosis within boys and girls.

RESULTS

Girls, but not boys, with ADHD showed overall reductions in total prefrontal cortex (PFC) SA. Localization revealed that girls showed widely distributed reductions in the bilateral dorsolateral PFC, left inferior lateral PFC, right medial PFC, right orbitofrontal cortex, and left anterior cingulate; and boys showed reduced SA only in the right anterior cingulate and left medial PFC. In contrast, boys, but not girls, with ADHD showed overall reductions in total premotor cortex (PMC) SA. Further localization revealed that in boys, premotor reductions were observed in bilateral lateral PMC regions; and in girls reductions were observed in bilateral supplementary motor complex. In line with diagnostic group differences, PMC and PFC SAs were inversely correlated with symptom severity in both girls and boys with ADHD.

CONCLUSIONS

These results elucidate sex-based differences in cortical morphology of functional subdivisions of the frontal lobe and provide additional evidence of associations among SA and symptom severity in children with ADHD.

Multimodal evaluation and management of children with concussion: using our heads and available evidence

BACKGROUND

Significant attention has been focused on concussions in children, but a dearth of research evidence exists supporting clinical evaluation and management.

AIM

The primary objective of this review paper is to describe a multimodal, developmentally adapted, standardized concussion assessment and active rehabilitation approach for children as young as 5 years old.

METHODS

This study reviews the CDC-funded research programme, including the development of tools for post-concussion symptom assessment involving the child and parent, measurement of specific neurocognitive functions and assessment of dynamic cognitive exertional effects.

RESULTS

A clinical approach to active, individualized, moderated concussion rehabilitation management is presented, including a 10-step guide to symptom management, with a specific focus on the school challenges faced by the recovering student.

CONCLUSION

To better inform concussion practice across the developmental age spectrum, a significant need exists for further research evidence to refine clinical assessment methods and develop effective treatment approaches.

Neurocognitive Profile of Children with Attention Deficit Hyperactivity Disorders (ADHD): A comparison between subtypes

OBJECTIVE

The aim of this study was to examine the differences between ADHD subtypes in executive function tasks compared to themselves and normal controls.

METHOD

In this study, 45 school aged children with Attention Deficit Hyperactivity Disorder (ADHD) and 30 normal children who were matched based on age and IQ score in Wechsler Intelligence Scale for Children-Revised (WISC-R) were compared in terms of executive function. We used Wisconsin Sorting Card Test to assess executive function in both groups. We also used children's scores in Children Symptom Inventory-4 (CSI-4) for diagnosing ADHD and specifying ADHD subtypes. Data were entered in SPSS-17 and analyzed by T-test and ANOVA static tests to clarify the differences between ADHD and controls and between ADHD subtypes. Scheffe's test was also used to identify which groups were different from one another. The mean and standard divisions (SD) were used for descriptive analysis.

RESULTS

ADHD subtypes are significantly different in terms of perseverative responses (p≤ 0/01) and perseverative errors (p≤ 0/001). Based on Scheffe's test, Attention Deficit Hyperactivity Disorders-Hyperactive type (ADHD-H) is not that different from Attention Deficit Hyperactivity Disorders-Inattention type (ADHD-I) and Attention Deficit Hyperactivity Disorders-Combined type (ADHD-C), but there are significant responses and perseverative differences between ADHD-I and ADHD-C in terms of perseverative errors. ADHD-C shows more perseverative responses and perseverative errors than ADHD-I.

CONCLUSION

The findings of this study revealed that executive function patterns are different in children with ADHD compared to normal children. In this study it was also found that ADHD subtypes are also different in terms of perseveration and response inhibition domains; ADHD-C has more deficits in these domains.

Sex differences in attention Deficit Hyperactivity Disorder: candidate genetic and endocrine mechanisms

Attention Deficit Hyperactivity Disorder (ADHD) is a developmental condition characterised by severe inattention, pathological impulsivity and hyperactivity; it is relatively common affecting up to 6% of children, and is associated with a risk of long-term adverse educational and social consequences. Males are considerably more likely to be diagnosed with ADHD than females; the course of the disorder and its associated co-morbidities also appear to be sensitive to sex. Here, I discuss fundamental biological (genetic and endocrine) mechanisms that have been shown to, or could theoretically, contribute towards these sexually dimorphic phenomena. Greater understanding of how and why the sexes differ with respect to ADHD vulnerability should allow us to identify and characterise novel protective and risk factors for the disorder, and should ultimately facilitate improved diagnosis, prognosis and treatment.

Executive function in children with attention deficit/hyperactivity disorder: the NIH EXAMINER battery

Theories of attention deficit/hyperactivity disorder (ADHD) increasingly highlight the role of neuropsychological impairment in ADHD; however, a consistent and identifiable pattern of performance on tests is not well established. The National Institutes of Health (NIH) Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (EXAMINER) battery provides measures of common variance across multiple executive function tests within specific domains and was used to characterize which executive functions are most affected in children with ADHD. Thirty-two children (24 male), ages 8-15 years (M = 12.02; SD = 2.29), diagnosed with ADHD and no comorbid disorder completed the NIH EXAMINER battery. Sixty age and gender matched healthy controls were chosen from a database of participants enrolled in the NIH EXAMINER multi-site study. Children with ADHD performed worse on the working memory score compared with the controls. No differences were found on the cognitive control or fluency scores. For children with ADHD, poorer working memory performance predicted parent report of child learning problems. Cognitive control and fluency scores did not predict learning problems. In summary, working memory emerges as a primary impairment in children with ADHD who have no comorbid disorders. Furthermore, working memory weaknesses may underlie the academic problems often seen in children with ADHD.

Evaluation of planning dysfunction in attention deficit hyperactivity disorder and autistic spectrum disorders using the zoo map task

Attention-Deficit-Hyperactivity-Disorders (ADHD) and Autistic-Spectrum-Disorders (ASD) share overlapping clinical and cognitive features that may confuse the diagnosis. Evaluation of executive problems and planning dysfunction may aid the clinical diagnostic process and help disentangle the neurobiological process underlying these conditions. This study evaluates the planning function problems in 80 male children and adolescents diagnosed with ADHD and 23 male children and adolescents with ASD using the Zoo Map Task; both groups were comparable in terms of age and IQ. The relationship between planning function and other executive functions is also assessed. In comparison to the ADHD groups, ASD children presented more errors in the open-ended tasks; these planning function problems seem to be mediated by processing speed and motor coordination, however it does not seem to be mediated by other executive function problems, including attention, working memory or response inhibition. In the time for planning, an interaction between the specific subgroups and working memory components was observed. ADHD and ASD present with different patterns of planning function, even when other components of executive function are taken into account; clinical and educational implications are discussed.

Wechsler Intelligence Scale for Children 4th edition-Chinese version index scores in Taiwanese children with attention-deficit/hyperactivity disorder

AIM

The Wechsler Intelligence Scale for Children 4th edition-Chinese version (WISC-IV-Chinese) has been in clinical use in Taiwan since 2007. Research is needed to determine how the WISC-IV, modified from its earlier version, will affect its interpretation in clinical practice in a Mandarin-speaking context.

METHODS

We attempted to use WISC-IV-Chinese scores to identify the cognitive strengths and weaknesses in 334 Taiwanese children with attention-deficit/hyperactivity disorder (ADHD). Comparison of cognitive profiles of WISC-IV-Chinese scores between subtypes of ADHD was also performed.

RESULTS

The results indicated that the four-factor model of the WISC-IV-Chinese fitted well for Taiwanese children with ADHD. The profiles showed that performance in the index score of the Processing Speed Index was the weakness domain for the Taiwanese children with ADHD, as confirmed by two different kinds of analytic methods. Cognitive profile analysis of ADHD subtypes revealed children with inattentive subtypes to have a greater weakness in processing speed performance.

CONCLUSION

The implications of the profiles of the index scores on the WISC-IV-Chinese version for Taiwanese children with ADHD were explored.

Neuropsychological performance and attention-deficit hyperactivity disorder subtypes and symptom dimensions

OBJECTIVE

Characterization of clinical heterogeneity in attention-deficit hyperactivity disorder (ADHD) remains controversial. Neuropsychological and cognitive studies provide one type of validation data, but too often have considered only a narrow range of functional domains.

METHOD

The current study examined ADHD subtype and presentation differences across a broad range of neurocognitive domains in a large clinically characterized, community-recruited sample of 498 youth (213 control, 107 ADHD-primarily inattentive [ADHD-PI], 137 ADHD-combined [ADHD-C]), ages 6-17 years. Domains assessed included inhibition, working memory, arousal, processing speed, response variability, and temporal information processing.

RESULTS

Youth with ADHD-C performed worse than youth with ADHD-PI in all domains, consistent with a severity model. Performance among a subgroup with a "restrictive inattentive" presentation indicated potential deficits in processing speed relative to other ADHD-PI youth, but no other effects. When all measures were included in the same model, cognitive control (executive functions, working memory, and memory span), arousal, and response variability each provided uniquely incremental statistical prediction of specific symptom dimensions and of subtype/presentation, but temporal information processing and processing speed did not.

CONCLUSION

Results suggest the potential to consolidate multiple neurocognitive theories of ADHD, and that such consolidation will apply across putative clinical subtypes or presentations.

Short sleep duration is associated with teacher-reported inattention and cognitive problems in healthy school-aged children

PURPOSE

Pediatric, clinical, and research data suggest that insufficient sleep causes tiredness and daytime difficulties in terms of attention-focusing, learning, and impulse modulation in children with attention deficit hyperactivity disorder (ADHD) or in those with ADHD and primary sleep disorders. The aim of the present study was to examine whether sleep duration was associated with ADHD-like symptoms in healthy, well-developing school-aged children.

PATIENTS AND METHODS

Thirty-five healthy children (20 boys, 15 girls), aged 7-11 years participated in the present study. Each child wore an actigraphic device on their nondominant wrist for two nights prior to use of polysomnography to assess their typical sleep periods. On the third night, sleep was recorded via ambulatory assessment of sleep architecture in the child's natural sleep environment employing portable polysomnography equipment. Teachers were asked to report symptoms of inattention and hyperactivity/impulsivity on the revised Conners Teacher Rating Scale.

RESULTS

Shorter sleep duration was associated with higher levels of teacher-reported ADHD-like symptoms in the domains of cognitive problems and inattention. No significant association between sleep duration and hyperactivity symptoms was evident.

CONCLUSION

Short sleep duration was found to be related to teacher-derived reports of ADHD-like symptoms of inattention and cognitive functioning in healthy children.

Working memory influences processing speed and reading fluency in ADHD

Processing-speed deficits affect reading efficiency, even among individuals who recognize and decode words accurately. Children with ADHD who decode words accurately can still have inefficient reading fluency, leading to a bottleneck in other cognitive processes. This "slowing" in ADHD is associated with deficits in fundamental components of executive function underlying processing speed, including response selection. The purpose of the present study was to deconstruct processing speed in order to determine which components of executive control best explain the "processing" speed deficits related to reading fluency in ADHD. Participants (41 ADHD, 21 controls), ages 9-14 years, screened for language disorders, word reading deficits, and psychiatric disorders, were administered measures of copying speed, processing speed, reading fluency, working memory, reaction time, inhibition, and auditory attention span. Compared to controls, children with ADHD showed reduced oral and silent reading fluency and reduced processing speed-driven primarily by deficits on WISC-IV Coding. In contrast, groups did not differ on copying speed. After controlling for copying speed, sex, severity of ADHD-related symptomatology, and GAI, slowed "processing" speed (i.e., Coding) was significantly associated with verbal span and measures of working memory but not with measures of response control/inhibition, lexical retrieval speed, reaction time, or intrasubject variability. Further, "processing" speed (i.e., Coding, residualized for copying speed) and working memory were significant predictors of oral reading fluency. Abnormalities in working memory and response selection (which are frontally mediated and enter into the output side of processing speed) may play an important role in deficits in reading fluency in ADHD, potentially more than posteriorally mediated problems with orienting of attention or perceiving the stimulus.

Linkages between childhood executive functioning and adolescent social functioning and psychopathology in girls with ADHD

We followed an ethnically and socioeconomically diverse sample of preadolescent girls with ADHD (n = 140) and matched comparison girls (n = 88) over a period of 5 years, from middle childhood through early/midadolescence, with the aim of determining whether childhood levels of executive function (EF) would predict adolescent multi-informant outcomes of social functioning and psychopathology, including comorbidity between externalizing and internalizing symptomatology. Predictors were well-established measures of planning, response inhibition, and working memory, along with a control measure of fine motor control. Independent of ADHD versus comparison group status, (a) childhood planning and response inhibition predicted adolescent social functioning and (b) childhood planning predicted comorbid internalizing/externalizing disorders in adolescence. Subgroup status (ADHD-Combined, ADHD-Inattentive, and comparison) moderated the relationship between childhood planning and adolescent internalizing/externalizing comorbidity, with the combined type revealing particularly strong associations between baseline planning and adolescent comorbidity. Mediation analyses indicated that adolescent social functioning mediated the prediction from childhood EF to comorbidity at follow-up; in turn, in the girls with ADHD, adolescent comorbidity mediated the prediction from childhood EF to social functioning at follow-up. We conclude that childhood interventions should target EF impairments in addition to behavioral symptoms.

Differences in Performance of ADHD Children on a Visual and Auditory Continuous Performance Test according to IQ

OBJECTIVE

Continuous performance tests (CPTs) are frequently used in clinical practice to assess the attentiveness of ADHD children. Although most CPTs do not categorize T scores by intelligence, there is great diversity of opinion regarding the interrelation between intelligence and CPT performance. This study aimed to determine if ADHD children with superior IQs would perform better than ADHD children with average IQs. Additionally, we aimed to examine the need for CPTs' to categorize according to IQ.

METHODS

Participants were 326 outpatients, aged 5-15 years, diagnosed with ADHD. All participants completed the Wechsler Intelligence Scale for Children-Revised and a CPT. After excluding those who meet exclusion criteria, we had 266 patients for our analysis.

RESULTS

The "Highly Intelligent Group" (HIG), patients with IQs 120 and above, performed superiorly to the "Normally Intelligent Group" (NIG) patients, with IQs between 70 and 120, with regard to omission and commission errors on the visual-auditory CPT, even after controlling for age and gender. The HIG had higher ratios of subjects with T scores <65 on the visual and auditory CPT variables than the NIG did.

CONCLUSION

The results of this study suggest this CPT is not sensitive for discerning ADHD in children with superior IQs; thus, there is a need to standardize the variables based on IQ, as well as on age and gender. Moreover, clinicians need to pay attention to the effect of IQ in interpreting CPT scores; that is, a "normal" score does not rule out a diagnosis of ADHD.

Executive function deficits in children with attention-deficit/hyperactivity disorder and improvement with lisdexamfetamine dimesylate in an open-label study

OBJECTIVE

To assess the effects of lisdexamfetamine dimesylate (LDX) on executive function (EF) behaviors in children with attention-deficit/hyperactivity disorder (ADHD).

METHODS

This observational, open-label, 7-week, dose-optimization study of LDX (20-70  mg/day) in children with ADHD evaluated efficacy with the ADHD Rating Scale IV; safety measures included adverse events (AEs). EF was assessed with the Behavior Rating Inventory of Executive Function (BRIEF). Post hoc analyses examined BRIEF scores by sex, ADHD subtype, comorbid psychiatric symptoms, and common treatment-emergent AEs (TEAEs). ADHD Rating Scale IV scores were assessed in subjects categorized by baseline BRIEF global executive composite T scores with clinically significant (≥65) or not clinically significant (<65) impairment in EF.

RESULTS

Mean (standard deviation) change from baseline to endpoint for BRIEF of -17.9 (12.5) for Global Executive Composite, -15.4 (12.6) for Behavioral Regulation Index, and -17.6 (12.3) for Metacognition Index demonstrated improvement with LDX (pooled doses; p < 0.0001 for all). Improvements in BRIEF scores were seen regardless of sex, ADHD subtype, comorbid psychiatric symptoms, common TEAEs, or baseline EF impairment category. TEAEs included decreased appetite, decreased weight, irritability, insomnia, headache, upper abdominal pain, and initial insomnia.

CONCLUSIONS

Improvements were demonstrated in EF behaviors and ADHD symptoms with LDX. LDX safety profile was consistent with long-acting stimulant use.

Neuropsychological profile of executive function in girls with attention-deficit/hyperactivity disorder

The majority of research on neurobehavioral functioning among children with Attention-Deficit/Hyperactivity Disorder (ADHD) is based on samples comprised primarily (or exclusively) of boys. Although functional impairment is well established, available research has yet to specify a neuropsychological profile distinct to girls with ADHD. The purpose of this study was to examine performance within four components of executive function (EF) in contemporaneously recruited samples of girls and boys with ADHD. Fifty-six children with ADHD (26 girls) and 90 controls (42 girls), ages 8-13, were administered neuropsychological tests emphasizing response inhibition, response preparation, working memory, and planning/shifting. There were no significant differences in age or SES between boys or girls with ADHD or their sex-matched controls; ADHD subtype distribution did not differ by sex. Compared with controls, children with ADHD showed significant deficits on all four EF components. Girls and boys with ADHD showed similar patterns of deficit on tasks involving response preparation and working memory; however, they manifested different patterns of executive dysfunction on tasks related to response inhibition and planning. Girls with ADHD showed elevated motor overflow, while boys with ADHD showed greater impairment during conscious, effortful response inhibition. Girls, but not boys with ADHD, showed impairment in planning. There were no differences between ADHD subtypes on any EF component. These findings highlight the importance of studying boys and girls separately (as well as together) when considering manifestations of executive dysfunction in ADHD.

Executive dysfunction screening and intelectual coefficient measurement in children with attention deficit hyperactivity disorder

OBJECTIVE: To perform a complete Intelligence quotient (IQ) measurement (verbal, performance, and total) and subsequently, to compare executive function (EF) measurements in subgroups of children with attention deficit-hyperactivity disorder (ADHD) with a control group. METHOD: We studied a group of children from 7-12 years of age from public elementary schools. Children were selected by means of Diagnostic and Statistical Manual of Mental Disorders-IV-Revised (DSM-IV-R) parent and teacher questionnaires for ADHD. EFs were screened by Weschler Intelligence Scale for Children (WISC-R) performance intelligence quotient (IQ) determination of the following sub-tests: picture completion; block designs, and object assembly tests. Simultaneously, total (T-), performance (P-), and verbal (V-) IQs were measured for each patient. RESULTS: We studied 26 control subjects, and 35 children with ADHD. Numbers of children in each ADHD sub-type group were as follows: 15 in the combined group (-C), 13 in the inattentive group (-I), and 7 in hyperactivity group (-H). We found significant lower EF scores in picture arrangement (F=3.76, df 3,57, p=0.01), block design (F=4.55, df 3,57, p<0.01), and object assembly (F=4.52, df 3,57, p<0.01). Post-hoc analysis showed that differences were located among ADHD-C, ADHD-I, and ADHD-H groups when compared with controls. We found significantly lower cognitive scores in the ADHD-I group as follows: P-IQ (F=3.57, df 3,57, p=0.02), and T-IQ (F=2.90, df 3,57, p=0.04). CONCLUSION: Our results showed that screening of EF alteration in children with ADHD is easy and rapid by means of certain P-IQ determination sub-scales of the WISC test; moreover, complementary IQ determination can be measured simultaneously. Overall, children with ADHD exhibited an EF alteration. ADHD-I children demonstrated lower P-IQ, and T-IQ scores than control children.

Sex differences in attentional performance and their modulation by methylphenidate in children with attention-deficit/hyperactivity disorder

BACKGROUND

Still little is known about neuropsychological differences between boys and girls with attention-deficit/hyperactivity disorder (ADHD) and whether there are sex-specific differences in the modulation of attentional performance by methylphenidate (MPH).

METHOD

In this study, 27 males and 27 females between 8-12 years old and with ADHD were investigated in a double-blind, placebo-controlled trial on five computerized attention tests (0.25 vs. 0.5 mg/kg MPH as a single dose, versus placebo).

RESULTS

Boys and girls with ADHD did not differ with respect to age, intelligence quotient (IQ), symptom severity, co-morbidity patterns, and ADHD subtype. However, ADHD boys were more impulsive on a sustained attention task, whereas girls with ADHD had more deficits on tasks measuring selective attention. Attentional performance increased differentially as a function of MPH dose, with some tasks showing linear improvement with higher dosage whereas more complex tasks in particular showed inverse U-shaped patterns of MPH effects. However, these effects were comparable between girls and boys.

CONCLUSIONS

Our data suggest that there are some gender differences in attentional performance in subjects with ADHD in a clinical sample, even if symptom severity and co-morbidity are controlled; however, modulation of attention by MPH does not seem to differ between sexes.

Gender differences in attention-deficit/hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD) is recognized to exist in males and females although the literature supports a higher prevalence in males. However, when girls are diagnosed with ADHD, they are more often diagnosed as predominantly inattentive than boys with ADHD. This article provides a review of gender differences noted across the lifespan. Males and females with ADHD are more similar than different, and generally ADHD profiles are not sex specific. Small gender differences have been found: adolescent girls with ADHD have lower self-efficacy and poorer coping strategies than adolescent boys with ADHD; rates of depression and anxiety may be higher, and physical aggression and other externalizing behaviors lower in girls and women with ADHD. Men with ADHD seem to be incarcerated more often than women with ADHD. However, many studies suffer from small sample sizes, referral biases, differences in diagnostic procedures, and possible rater influences. Treatments are reviewed and discussed with reference to the reported gender differences in functioning and the global deficits noted in all samples. The data available so far suggest that treatments are likely to be equally effective in males and females. However, referral bias is a problem, in that females with ADHD are less likely to be referred for treatment than males with ADHD. Future research should include equal representation of both sexes in samples such that sex by treatment analyses can be routinely conducted.

Developmental changes in semantic verbal fluency: analyses of word productivity as a function of time, clustering, and switching

We investigated age-related improvement in semantic category verbal fluency (VF) in 309 Dutch schoolchildren attending first to ninth grade. Quantitative analyses of number of correct responses as a function of time as well as qualitative analyses of clustering and switching were conducted. Overall, Dutch VF task performance, i.e., number of correct responses over 60 seconds, was not established before mid-adolescence. This is in line with previously published studies, using VF number of correct responses over 60 seconds as the main outcome measure and examining VF task performance across other cultures and languages (e.g., Italian, French, Hebrew). Next, mean cluster size, a measure of lexico-semantic knowledge, was not established until at least grade 3. In contrast, performance on the VF outcome measures "number of switches/clusters" was established at least 4 years later. Qualitative and quantitative Design Fluency (DF) outcome measures support the notion that the numbers of switches/clusters are valid measures of higher order cognitive functions, such as strategy use and cognitive flexibility. In line of this, VF number of correct responses during 16-60 seconds, a measure of controlled information processing, is established at least 2 years later (i.e., grades 7-8) than number of correct responses during the first 15 seconds time slide, a measure of automatic processing. Finally, environment, i.e., the level of parental education, primarily affected automatic and lexico-semantic knowledge. No effects of sex on VF performance were found. These data suggest that the alternative scoring methods of VF tasks can be used to acquire knowledge on development of lower and higher order cognitive functions in healthy children and the influence of the environment on it.

Age-related changes in motor subtle signs among girls and boys with ADHD

OBJECTIVE

To examine differences in age-related improvement in motor speed and neurologic subtle signs (overflow and dysrhythmia) among boys and girls with and without attention-deficit hyperactivity disorder (ADHD).

METHOD

Diagnosis of ADHD was determined by structured parent interview and administration of ADHD-specific and broad behavior rating scales. Motor function was assessed using the revised Physical and Neurological Assessment of Subtle Signs. Three primary outcome variables were obtained: 1) total time, 2) total overflow, and 3) total dysrhythmia. Effects of age, group, and sex were assessed.

RESULTS

Both control and ADHD groups showed improvement on timed tasks with age; however, controls were consistently faster across the age span. Controls and girls with ADHD showed steady age-related reduction of overflow and dysrhythmia, whereas boys with ADHD had little improvement in these signs through age 14 years.

CONCLUSION

Results indicated that girls with attention-deficit hyperactivity disorder (ADHD) performed similarly to age-matched controls on a quantified motor examination. These results parallel patterns of findings from neuroimaging studies, in which neurologic anomalies in areas related to motor control are present in boys with ADHD, but more equivocal in girls with ADHD. Sex-related differences observed in children with ADHD likely extend beyond symptom presentation to development of motor control, and are likely related to earlier brain maturation in girls.

The neurobiological profile of girls with ADHD

Since boys are more commonly diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) than girls, the majority of theories and published research studies of ADHD have been based on samples comprised primarily (or exclusively) of boys. While psychosocial impairment in girls with ADHD is well established, the neuropsychological and neurobiological basis of these deficits is less consistently observed. There is growing evidence that boys' and girls' brains develop and mature at different rates, suggesting that the trajectory of early anomalous brain development in ADHD may also be sex-specific. It remains unclear, however, whether earlier brain maturation observed in girls with ADHD is protective. In this review, we outline the current theory and research findings that seek to establish a unique neurobiological profile of girls with ADHD, highlighting sex differences in typical brain development and among children with ADHD. The review highlights findings from neurological, neurocognitive, and behavioral studies. Future research directions are suggested, including the need for longitudinal neuroimaging and neurobehavioral investigation beginning as early as the preschool years, and continuing through adolescence and adulthood, with consideration of identified sex differences in the development of ADHD.