Self-regulation and inhibition in comorbid ADHD children: an evaluation of executive functions

Attention-deficit/hyperactivity disorder and behavioural planning deficiencies in South African primary school children

Background

Attention-deficit/hyperactivity disorder (ADHD) is defined as a cognitive or behavioural developmental disorder. Inattentiveness, overactivity and impulsivity are regarded as the main clinical symptoms of ADHD. These symptoms may occur together or separately resulting in three recognised presentations: predominantly inattentive, predominantly hyperactive–impulsive and combined presentations.

Aim

This study investigated deficiencies in behavioural planning in South African primary school children with and without ADHD.

Setting

Tzaneen area in Limpopo province, South Africa.

Methods

A total of 156 children (78 with ADHD and 78 matched controls without ADHD) of both genders, who were medication naïve and aged 6–15 years, participated in the study. The performance of the two groups was compared on a test of planning and problem-solving, the Tower of London (ToL) task. The results were analysed as a function of gender, age and ADHD presentation.

Results

Children with ADHD especially ADHD-PI and ADHD-C used significantly more moves and took a longer time to complete the task than the controls (p < 0.001). There were no significant differences in the number of moves and time taken by the predominantly hyperactive-impulsive presentations of ADHD when compared to the controls. Gender and age did not influence the performance.

Conclusion

The results showed that children with ADHD showed significantly more deficits mainly the ADHD-PI and ADHD-C presentations, which indicates that inattention is mainly responsible for deficiencies in behaviour planning. The ADHD-HI presentations and the control group were not affected.

Behaviour planning and inhibitory control in Sepedi-speaking primary school children with attention-deficit/hyperactivity disorder

Attention-deficit hyperactivity disorder is one of the most common disorders that can occur in children. The symptoms are thought to result from a deficit in executive functions. This study investigated whether children with attention-deficit hyperactivity disorder subtypes differed in behavioural planning and response inhibition, two of the domains of executive functioning, from a control group without attention-deficit hyperactivity disorder symptoms. Furthermore, it examined whether the three attention-deficit hyperactivity disorder subtypes differed from each other in terms of performance. The sample ( n = 320) consisted of primary school children, aged between 6 and 14 years, from the Moletjie circuit (Limpopo). It consisted of an attention-deficit hyperactivity disorder group ( n = 160) and a control group ( n = 160). The Disruptive Behavioural Disorder rating scale was used to establish the symptoms of attention-deficit hyperactivity disorder. The Tower of London was used to measure planning ability, and the inhibition subtest (arrows and shapes) from the NEPSY-II (Developmental Neuropsychological Assessment, second edition) to measure response inhibition. Analysis of variance was employed to establish differences in subtype, gender, and age group. The results showed that children with the combined attention-deficit hyperactivity disorder subtype demonstrated significantly more deficits than the control group, in both behavioural planning and inhibition control. No significant differences between the hyperactive/impulsive and inattentive attention-deficit hyperactivity disorder subtypes and the control group were found. Gender and age did not influence performance with regard to planning and inhibition tasks. Correlations between planning behaviour and response inhibition were low, which suggests that they are distinct processes.

Executive Function Training for Children with Attention Deficit Hyperactivity Disorder

BACKGROUND

Accumulating evidence indicates that attention deficit hyperactivity disorder (ADHD) is associated with core deficits in executive function (EF) which predicts poorer academic and occupational functioning. This makes early intervention targeting EF impairments important to prevent long-term negative outcomes. Cognitive training is a potential ADHD treatment target. The present study aimed to explore the efficacy, feasibility, and acceptability of a cognitive training program (targeting child's multiple EF components and involving parent support in daily life), as a nonpharmacological intervention for children with ADHD.

METHODS

Forty-four school -age children with ADHD and their parents participated in 12 sessions of EF training (last for 12 weeks) and 88 health controls (HC) were also recruited. Training effects were explored using both neuropsychological tests (Stroop color-word test, Rey-Osterrieth complex figure test, trail making test, tower of Hanoi, and false-belief task) and reports of daily life (ADHD rating scale-IV, Conners' parent rating scale, and behavior rating inventory of executive function [BRIEF]) by analysis of paired sample t-test and Wilcoxon signed-rank test. The differences on EF performances between children with ADHD after training and HC were explored using multivariate analysis.

RESULTS

The results (before vs. after EF training) showed that after intervention, the children with ADHD presented better performances of EF both in neuropsychological tests (word interference of Stroop: 36.1 ± 14.6 vs. 27.1 ± 11.1, t = 4.731, P < 0.001; shift time of TMT: 194.9 ± 115.4 vs. 124.8 ± 72.4, Z = -4.639, P < 0.001; false-belief task: χ2 = 6.932, P = 0.008) and reports of daily life (global executive composite of BRIEF: 148.9 ± 17.5 vs. 127.8 ± 17.5, t = 6.433, P < 0.001). The performances on EF tasks for children with ADHD after EF training could match with the level of HC children. The ADHD symptoms (ADHD rating scale total score: 32.4 ± 8.9 vs. 22.9 ± 8.2, t = 6.331, P < 0.001) and behavioral problems of the children as reported by parents also reduced significantly after the intervention. Participants reported that the EF training program was feasible to administer and acceptable.

CONCLUSIONS

The EF training program was feasible and acceptable to children with ADHD and parents. Although replication with a larger sample and an active control group are needed, EF training program with multiple EF focus and parent involving in real-life activities could be a potentially promising intervention associated with significant EF (near transfer) and ADHD symptoms improvement (far transfer).

Hot and Cool Executive Functions in Children with Attention-Deficit/Hyperactivity Disorder and Comorbid Oppositional Defiant Disorder

While neuropsychological deficits in both "hot" and "cool" executive functions (EFs) have been documented among individuals with attention-deficit/hyperactivity disorder (ADHD), these EF deficits are not universal across all individuals with this diagnosis. One potential moderator of executive dysfunction may be the presence of comorbid oppositional defiant disorder (ODD). This study examined the association between "hot" and "cool" EFs and comorbid ODD in children with ADHD. Thirty-three children with ADHD and comorbid ODD (ADHD+ODD), 67 with ADHD without ODD (ADHD-ODD), and 30 typically developing controls participated. Children were 7-12 years of age. "Cool" EFs were assessed with a spatial span task and a card sorting test. "Hot" EFs were assessed using a delay discounting task and a gambling task. ADHD-ODD and ADHD+ODD groups performed more poorly on "cool" EF tasks than controls, but did not differ from each other. Furthermore, the number of ADHD symptoms, but not ODD symptoms, was associated with "cool" EF scores. The three groups did not differ on "hot" EF tasks and the number of ADHD or ODD symptoms was unrelated to "hot" EF scores. In sum, children with ADHD presented with "cool" EF deficits which appear to be unrelated to ODD comorbidity. However, "hot" EF deficits were not present among children with ADHD, irrespective of comorbid ODD status.

Prevalence and diagnostic validity of motivational impairments and deficits in visuospatial short-term memory and working memory in ADHD subtypes

Deficits in working memory (WM) and reinforcement sensitivity are thought to give rise to symptoms in the combined (ADHD-C) and inattentive subtype (ADHD-I) of ADHD. Children with ADHD are especially impaired on visuospatial WM, which is composed of short-term memory (STM) and a central executive. Although deficits in visuospatial WM and reinforcement sensitivity appear characteristic of children with ADHD on a group-level, the prevalence and diagnostic validity of these impairments is still largely unknown. Moreover, studies investigating this did not control for the interaction between motivational impairments and cognitive performance in children with ADHD, and did not differentiate between ADHD subtypes. Visuospatial WM and STM tasks were administered in a standard (feedback-only) and a high-reinforcement (feedback + 10 euros) condition, to 86 children with ADHD-C, 27 children with ADHD-I (restrictive subtype), and 62 typically developing controls (aged 8-12). Reinforcement sensitivity was indexed as the difference in performance between the reinforcement conditions. WM and STM impairments were most prevalent in ADHD-C. In ADHD-I, only WM impairments, not STM impairments, were more prevalent than in controls. Motivational impairments were not common (22% impaired) and equally prevalent in both subtypes. Memory and motivation were found to represent independent neuropsychological domains. Impairment on WM, STM, and/or motivation was associated with more inattention symptoms, medication-use, and lower IQ scores. Similar results were found for analyses of diagnostic validity. The majority of children with ADHD-C is impaired on visuospatial WM. In ADHD-I, STM impairments are not more common than in controls. Within both ADHD subtypes only a minority has an abnormal sensitivity to reinforcement.

Contrasting deficits on executive functions in Chinese delinquent adolescents with attention deficit and hyperactivity disorder symptoms and/or reading disability

Many studies reported high prevalence of reading disability (RD) and attention deficit hyperactivity disorder (ADHD) among delinquent adolescents. Very few have examined their cognitive profile. The present study compared the executive functions (EFs) and severity of delinquency in delinquent adolescents with RD and/or ADHD symptoms (AS). Delinquents with AS (n=29), RD (n=24), comorbidity AS+RD (n=35) were recruited from juvenile institutions along with typically developing controls (n=29) from local schools; all completed EF assessments and self-report questionnaires on delinquency. Results showed that pure AS group exhibited impaired inhibition while the pure RD group was weak in processing speed and visual memory. The comorbidity group showed unique impairments in interference control and significantly higher delinquency severity. The present findings suggest that comorbidity AS+RD may influence delinquency severity. It also provides a more comprehensive picture of the unique EF deficits associated with different groups, allowing for better matching for future identification and intervention programme.

Cool and hot executive function in conduct-disordered adolescents with and without co-morbid attention deficit hyperactivity disorder: relationships with externalizing behaviours

BACKGROUND

An understanding of the exact nature of executive function (EF) deficits in conduct disorder (CD) remains elusive because of issues of co-morbidity with attention deficit hyperactivity disorder (ADHD).

METHOD

Seventy-two adolescents with CD, 35 with CD + ADHD and 20 healthy controls (HCs) were assessed on a computerized battery of putative 'cool' and 'hot' EFs. Participants also completed the Child Behaviour Checklist (CBCL).

RESULTS

In the cool EF tasks such as planning, the CD + ADHD group in particular showed most notable impairments compared to HCs. This pattern was less evident for set shifting and behavioural inhibition but there were significant correlations between errors scores on these tasks and indices of externalizing behaviours on the CBCL across the sample. For hot EF tasks, all clinical groups performed worse than HCs on delay of gratification and poor performance was correlated with externalizing scores. Although there were no notable group differences on the punishment-based card-playing task, there were significant correlations between ultimate payout and externalizing behaviour across groups.

CONCLUSIONS

Overall, our findings highlight the fact that there may be more common than distinguishing neuropsychological underpinnings to these co-morbid disorders and that a dimensional symptom-based approach may be the way forward.

What part of working memory is not working in ADHD? Short-term memory, the central executive and effects of reinforcement

Deficits in Working Memory (WM) are related to symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD). In children with ADHD visuospatial WM is most impaired. WM is composed of Short-Term Memory (STM) and a Central Executive (CE). Therefore, deficits in either or both STM and the CE may account for WM impairments in children with ADHD. WM-component studies investigating this find deficits in both STM and the CE. However, recent studies show that not only cognitive deficits, but also motivational deficits give rise to the aberrant WM performance of children with ADHD. To date, the influence of these motivational deficits on the components of WM has not been investigated. This study examined the effects of a standard (feedback-only) and a high level of reinforcement (feedback + 10 euros) on the visuospatial WM-, visuospatial STM-, and the CE performance of 86 children with ADHD and 62 typically-developing controls. With standard reinforcement the STM, CE, and WM performance of children with ADHD was worse than that of controls. High reinforcement improved STM and WM performance more in children with ADHD than in controls, but was unable to normalize their performance. High reinforcement did not appear to improve the CE-related performance of children with ADHD and controls. Motivational deficits have a detrimental effect on both the visuospatial WM performance and the STM performance of children with ADHD. Aside from motivational deficits, both the visuospatial STM and the CE of children with ADHD are impaired, and give rise to their deficits in visuospatial WM.

[The performance of children with AD(H)D according to the HAWIK-IV]

The focus of the present study were performances of N = 433 children and adolescents with AD(H)D on the German version of the Wechsler Intelligence Scale for children (HAWIK-IV). Furthermore, we investigated whether test results depend on comorbid disorders based on subgroups (n = 212, n = 262, n = 217) composed by excluding individuals based on comorbidities on either (a) the first, (b) the second, and (c) the first and the second axis of the multiaxial classification scheme for mental disorders in childhood and adolescents. The specificity of the AD(H)D profile was investigated by comparing it against a clinical control group of children with anxiety or other emotional disorders (N = 41). As expected, a significant deficit in the Speed Index was shown not only in the total sample of all AD(H)D children, but also in the subsample cleared of comorbidities. There was also a deficit in Working Memory, although this result was no longer found in the subsample of AD(H)D children without comorbidities. The profile of the AD(H)D-only group was not significantly different from the profile of the clinical control group. The results support the assumption that AD(H)D is associated with deficits in Processing Speed. Working Memory deficits seem to occur only if comorbid disorders are present.

Executive and intellectual functions in attention-deficit/hyperactivity disorder with and without comorbidity

BACKGROUND

Recent neuropsychological theories have targeted deficient executive functions (EF) as the main characteristic of Attention Deficit Hyperactivity Disorder (ADHD), but the nature of the neuropsychological deficits remains elusive and findings are heterogeneous. In particular, it is still unclear whether ADHD subtypes and comorbidity affect intellectual and executive functioning, because large variability has been found in different patient populations. Furthermore, the role of IQ in EF deficits in individuals with ADHD has been debated.

METHODS

The aim of the present research was to study in detail the relationship between EF, ADHD subtypes, and comorbid diagnosis by taking into account the potential role of IQ. For this purpose, 23 children (aged from 5 to 16 years; 20 males and 3 females) with a diagnosis of ADHD were selected.

RESULTS

Data show no differences between children with different subtypes of ADHD on measures of EF, but they evidence differences on EF measures in children with different comorbidities (internalizing versus externalizing disorder). Namely, compared to the internalizing disorders group, the children with externalizing disorders obtained significantly lower scores on different measures of EF (i.e., verbal working memory and categorical fluency), but these differences were strictly dependent on IQ level.

CONCLUSIONS

Comorbidity patterns, rather than ADHD subtypes, appear to be more valid for defining the neuropsychological features of the ADHD endophenotype. Moreover, general intelligence seems to play a substantial role in the cognitive processes underling the disorder, especially in relation to externalizing aspects.

Source-specific oppositional defiant disorder among inner-city children: prospective prediction and moderation

We examined prospective prediction from parent- and teacher-reported oppositional defiant disorder (ODD) symptoms to parent-reported ODD, conduct disorder (CD), major depressive disorder (MDD), and generalized anxiety disorder symptoms and whether child executive functioning abilities moderated these relations among an urban, low-income sample of first- to third-grade children (N = 87). Time 1 parent-reported ODD predicted each Time 2 outcome. Time 1 teacher-reported ODD predicted Time 2 CD and MDD symptoms. After controlling for Time 1 co-occurring symptoms, only prediction from Time 1 teacher-reported ODD to CD and MDD symptoms remained significant. Child executive functioning abilities moderated relations between Time 1 parent-reported ODD and Time 2 ODD, and Time 1 teacher-reported ODD and Time 2 CD and MDD. Among children with better executive functioning abilities, higher Time 1 ODD was associated with higher Time 2 symptoms.

Executive function profile of Chinese boys with attention-deficit hyperactivity disorder: different subtypes and comorbidity

This study examined the executive function (EF) profile of Chinese boys with attention-deficit hyperactivity disorder (ADHD) using a large sample. Executive function performance within the ADHD subtypes and the effects of comorbidity were also investigated. Five hundred Chinese boys (375 with ADHD and 125 controls) aged 6-15 completed a battery of EF tests. Boys with all types of ADHD performed worse in all of the EF tests than age- and intelligence quotient-matched healthy controls. The boys with the inattention ADHD subtype and the combined subtype showed similar impairments across different EF tasks, whereas the boys with the hyperactive-impulsive ADHD subtype primarily displayed deficits in theory of mind and visual memory. Comorbid oppositional defiant disorder/conduct disorder had no additional influence on the EF characteristics of the boys with ADHD only, whereas comorbid learning disorder increased the severity of inhibition and shifting impairments.

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.

Neurocognitive function in attention-deficit-hyperactivity disorder with and without comorbid disruptive behaviour disorders

OBJECTIVE

The aim of the present study was to examine the effect of comorbid oppositional defiant disorder (ODD) and conduct disorder (CD) on (i) symptom levels in attention-deficit-hyperactivity disorder (ADHD) and (ii) the relationship between neurocognitive impairment and ADHD symptom severity.

METHOD

A total of 200 6-12-year-old children with DSM-IV ADHD, combined type (ADHD-CT) were identified in a specialist ADHD clinic in metropolitan Melbourne. From this initial group, 23 were identified with ADHD without ODD/CD (ADHD alone), 22 had ADHD and ODD and 20 had ADHD and CD. All the children were medication naive. Twenty-five healthy control children were also recruited from local primary schools. The four groups did not differ in age, gender or full-scale IQ. A cross-sectional study of parent- and teacher-reported ADHD and externalizing symptoms, spatial span, spatial working memory, visuospatial memory, spatial recognition, spatial planning and behavioural inhibition was completed.

RESULTS

Parent-reported externalizing symptoms were higher in the ADHD + CD and ADHD + ODD groups compared to the ADHD alone group. There were no differences in neurocognitive function between children with ADHD-CT with and without ODD or CD. All the ADHD groups, however, performed worse than the healthy control group. Further, worse spatial span, spatial working memory and delayed matching to sample performance were associated with increased teacher-reported ADHD symptoms in the ADHD alone group. Also, worse spatial working memory performance was associated with increased teacher-reported ADHD symptoms in the ADHD + CD group.

CONCLUSIONS

ADHD symptom severity is associated with the magnitude of impairment in executive functions in children with ADHD alone, but these relationships can be obscured by the presence of comorbid disruptive disorders. Children with ADHD + CD may demonstrate similar associations to children with ADHD alone, suggesting a similar underlying dysfunction. ADHD + ODD, however, may be better understood as a maladaptive response to the abnormal behaviours and neurocognitive functions in ADHD.

ADHD subtypes and co-occurring anxiety, depression, and oppositional-defiant disorder: differences in Gordon diagnostic system and Wechsler working memory and processing speed index scores

OBJECTIVE

Wechsler Intelligence Scale for Children Freedom-from-Distractibility/Working Memory Index (FDI/WMI), Processing Speed Index (PSI), and Gordon Diagnostic System (GDS) scores in ADHD children were examined as a function of subtype and coexisting anxiety, depression, and oppositional-defiant disorder.

METHOD

Participants were 587 children with ADHD combined type (alone, with oppositional-defiant disorder, and with anxiety or depression) and ADHD inattentive type (alone and with anxiety or depression).

RESULTS

Attention scores (FDI/WMI and GDS Vigilance and Distractibility) were similar and low for all groups. ADHD combined groups had greater impulsivity (GDS Delay) than ADHD inattentive groups, and ADHD inattentive groups had slower processing speed (PSI) than ADHD combined groups. Comorbidity did not affect test performance. Scores differentiated ADHD subtypes with 72% accuracy.

CONCLUSION

Findings support the validity of DSM-IV ADHD combined and inattentive subtypes and the validity of the GDS, FDI/WMI, and PSI in assessing attention, impulsivity, and processing speed in children with ADHD.

Avaliação neuropsicológica dos transtornos psicológicos na infância: um estudo de revisão

Este artigo apresenta uma revisão da literatura sobre a avaliação neuropsicológica dos déficits cognitivos associados aos transtornos psicológicos na infância e adolescência, com base em pesquisas publicadas no período de 2000 a 2006. Foi realizado um levantamento abrangendo publicações nacionais e internacionais indexadas nas bases de dados Medline, SciELo e PsycInfo. Os resultados indicaram um aumento da produção científica na área da avaliação neuropsicológica do transtorno de déficit de atenção e hiperatividade, autismo, transtornos de humor e transtorno de conduta. Observou-se a presença de poucos estudos nacionais, indicando a necessidade de pesquisas na área de avaliação neuropsicológica no Brasil.