A Clinical Comparative Study Evaluating the Effect of Epilepsy Versus Adhd on Timed Cognitive Tasks in Children

Both children with epilepsy and children with ADHD may be characterized by slowing on reaction-time measurement. This is of particular interest, as neuropsychological assessment is often requested in the differential diagnosis between children with short non-convulsive epileptic seizures and children with ADHD. In this study we attempt to identify patterns of impairment on timed tasks that are specific for epilepsy, relative to ADHD. This study was an open, controlled parallel-group clinical investigation which included two groups of patients: 60 children with ADHD and 60 children with epilepsy. These children were compared with a control group (n =30) on two types of timed cognitive tasks: tasks with low information load (simple reaction-time measurement) and tasks with high information load (multiple decision reaction-time measurement). The simple reaction-time measurements show significant differences between ADHD and controls (all except for visual RT non-dominant hand) and between epilepsy and controls (only one test). No significant differences were found between epilepsy and ADHD. The two tests with high information load show significant slowing compared with the controls for epilepsy on the Binary Choice Reaction-Time Test and for ADHD on the Visual Searching Test. On both tests also the differences between epilepsy and ADHD are significant. The two tests in combination have a relatively satisfactory potential to classify the children with ADHD (75% correct classification) and the children with epilepsy (55% correct classification). We may conclude that complex reaction-time tests (i.e., timed tasks with high information load) have potential for assessing the differential impact of ADHD and epilepsy on attentional function. These tasks specifically reveal general slowing for children with epilepsy and slowing as an effect of failures of inhibitory self control on unstructured tasks for ADHD.     

Utility of a CPT in Diagnosing ADHD among a Representative Sample of High-Risk Children: A Cautionary Study

Continuous performance tests (CPTs) are widely used in the assessment and study of attention deficit hyperactivity disorder (ADHD). Although CPTs have reliably found differences between children with ADHD and normal controls, discriminating between children with ADHD and children with subclinical levels of behavioral or cognitive problems is a more clinically relevant and difficult endeavor. Additionally, most studies use convenience samples from clinical care settings that may not represent the ADHD population as a whole. The current study assessed the utility of a clinically used CPT, the Test of Variables of Attention (TOVA), in distinguishing between children with ADHD and children with subclinical levels of attention/behavior problems. Participants constituted a representative sample of elementary school students at high risk for ADHD, including 116 children with ADHD and 51 subclinical controls. Results found no significant differences between the ADHD and subclinical group on CPT variables, and CPT performance did not reliably predict group membership. Implications of the findings are discussed.     

Utility of a CPT in diagnosing ADHD among a representative sample of high-risk children: a cautionary study.

Continuous performance tests (CPTs) are widely used in the assessment and study of attention deficit hyperactivity disorder (ADHD). Although CPTs have reliably found differences between children with ADHD and normal controls, discriminating between children with ADHD and children with subclinical levels of behavioral or cognitive problems is a more clinically relevant and difficult endeavor. Additionally, most studies use convenience samples from clinical care settings that may not represent the ADHD population as a whole. The current study assessed the utility of a clinically used CPT, the Test of Variables of Attention (TOVA), in distinguishing between children with ADHD and children with subclinical levels of attention/behavior problems. Participants constituted a representative sample of elementary school students at high risk for ADHD, including 116 children with ADHD and 51 subclinical controls. Results found no significant differences between the ADHD and subclinical group on CPT variables, and CPT performance did not reliably predict group membership. Implications of the findings are discussed.     

Impaired Consonant Trigrams Test (CTT) performance relates to everyday working memory difficulties in children with Autism Spectrum Disorders

Individuals with Autism Spectrum Disorders (ASD) often struggle with complex tasks, such as those requiring divided attention (simultaneously completing two independent tasks) that also place high demands on working memory. Prior research shows that divided attention is impaired in adults and children with ASD and is related to ASD and comorbid attention deficit/hyperactivity disorder (ADHD) symptoms, but the impact on everyday functioning is unclear. Because ADHD symptoms are associated with poor divided attention and working memory performance in children with ASD, we also examined ADHD symptoms as moderators of divided attention performance. We examined performance on the Consonant Trigrams Test (CTT) between high-functioning 8- to 13-year-olds with ASD (n?=?28) and typically developing controls (n?=?18) matched on age and IQ. In the ASD group, we also correlated performance with ADHD symptoms and behavior ratings of everyday working memory. CTT performance in children with ASD was significantly worse than in matched controls. A significant correlation between CTT performance and everyday working memory was observed, but CTT performance was not related to comorbid ADHD symptoms in the ASD group. Divided attention with high working-memory demands is a relative weakness in children with high-functioning ASD; this weakness relates to everyday functioning, and it is independent from ADHD symptoms. That ADHD symptoms are not associated with divided attention performance is inconsistent with one prior investigation, which likely results from using different divided attention tasks in the two studies.     

两种亚型ADHD儿童在停止信号任务中的反应抑制

采用停止信号任务,操纵其中的反应冲突,探查两种亚型（注意缺陷型和混合型）ADHD儿童在不同抑制功能——反应冲突和反应停止上的表现,以及儿童在内源性和外源性两种注意条件下反应抑制的表现。结果发现,与正常儿童相比,ADHD儿童在两种反应抑制上都有不同程度的缺损,不仅冲突效应量更大,反应停止的错误率也更高;但在控制年龄因素后,未观察到两种亚型ADHD儿童之间在反应冲突和反应停止能力上有明显差异。研究还发现,儿童在内源性和外源性两种注意条件下反应抑制的表现模式相似,说明反应冲突和反应停止可能存在某些共同的神经机制,两种亚型ADHD儿童在这些机制的功能缺损上有类似之处。     

Differences in memory functioning between children with attention-deficit/hyperactivity disorder and/or focal epilepsy

Prior research has shown that attention-deficit/hyperactivity disorder (ADHD) and epilepsy are frequently comorbid and that both disorders are associated with various attention and memory problems. Nonetheless, limited research has been conducted comparing the two disorders in one sample to determine unique versus shared deficits. Hence, we investigated differences in working memory (WM) and short-term and delayed recall between children with ADHD, focal epilepsy of mixed foci, comorbid ADHD/epilepsy and controls. Participants were compared on the Core subtests and the Picture Locations subtest of the Children’s Memory Scale (CMS). Results indicated that children with ADHD displayed intact verbal WM and long-term memory (LTM), as well as intact performance on most aspects of short-term memory (STM). They performed worse than controls on Numbers Forward and Picture Locations, suggesting problems with focused attention and simple span for visual-spatial material. Conversely, children with epilepsy displayed poor focused attention and STM regardless of the modality assessed, which affected encoding into LTM. The only loss over time was found for passages (Stories). WM was intact. Children with comorbid ADHD/epilepsy displayed focused attention and STM/LTM problems consistent with both disorders, having the lowest scores across the four groups. Hence, focused attention and visual-spatial span appear to be affected in both disorders, whereas additional STM/encoding problems are specific to epilepsy. Children with comorbid ADHD/epilepsy have deficits consistent with both disorders, with slight additive effects. This study suggests that attention and memory testing should be a regular part of the evaluation of children with epilepsy and ADHD.     

Visuo-spatial working memory span: a sensitive measure of cognitive deficits in children with ADHD.

Working memory (WM) has been hypothesised to be impaired in attention-deficit/hyperactivity disorder (ADHD). However, there are few studies reported on tests measuring visuo-spatial WM (VSWM) in ADHD. Some of these studies used paradigms including episodic memory, others only used low memory loads. In the present study we used a VSWM test that has not been used previously in ADHD research. The sensitivity of the VSWM test and a choice reaction time (CRT) test was evaluated in a pilot study by comparing them to two commonly used tests in ADHD-research; the Continuous Performance Test (CPT) and a Go/no-go test, in children with and without ADHD. The groups differed significantly in performance on the VSWM test (P < .01) and CRT (P < .05) but not on the CPT (P > .1) or on the Go/no-go test (P > .1). The results from the VSWM and CRT tests were replicated in a larger sample of participants (80 boys; 27 boys with ADHD and 53 controls, mean age 11.4 years). The difference between the groups was significant for both the VSWM test (P < .01) and the CRT test (P < .01). The effect size (ES) of the VSWM test was 1.34. There was a significant age-by-group interaction on the VSWM test, with larger group differences for the older children (P < .01). Our results show that the VSWM test is a sensitive measure of cognitive deficits in ADHD and it supports the hypothesis that deficits in VSWM is a major component of ADHD.     

Errors on a computer task and subclinical symptoms of attention‐deficit/hyperactivity disorder (ADHD)

Previous reports have found increased error rate for children with attention‐deficit/hyperactivity disorder (ADHD ) on response time (RT ) computer tasks. Here we attempt the conceptual replication and extension of two studies that examined error rate in a general population of children (N = 203). Study 1 followed Johnstone and Galletta but considered associations between scores on a dimensional measure of ADHD symptoms (rather than comparing those with or without an ADHD diagnosis) and the frequency of commission and omission errors. Study 2 followed Shiels, Tamm & Epstein and examined post‐error adjustment in the same group of children as for Study 1. Study 1 did not replicate previous findings of no increase in errors of commission in those with higher ADHD symptoms (Johnstone & Galletta). Instead, we found that younger children with lower ADHD symptoms were more likely to make commission errors, while omission errors did not vary with age. Study 2 replicated the previous finding of less RT slowing in children with more ADHD symptoms, extending this finding to a general population of children. Namely, as ADHD symptoms increase, RT slowing is less likely, putting children with higher ADHD symptoms at risk of additional errors. Overall, we extend previous ADHD research to typically developing children with ADHD symptoms.     

Verbal fluency over time as a measure of automatic and controlled processing in children with ADHD

The performance of ADHD children on semantic category fluency (SCF) versus initial letter fluency (ILF) tasks was examined. For each participant, word production was recorded for each 15-s time slice on each task. Performance on both fluency tasks was compared to test the hypothesis that children with ADHD are characterized by a performance deficit on the ILF task because performance on this task is less automated than performance on the SCF. Children classified with ADHD (N = 20) were compared to children with other psychopathology (N = 118) and healthy controls (N = 130). Results indicated that the groups could not be differentiated by the total number of words produced in 60 s in either fluency task. As hypothesized, a significant interaction of group by productivity over time by type of fluency task was found: ADHD children had more problems finding words in the first 15 s of the IFL than did children in the other two groups, and as compared with their performance on the SCF. Results were taken to indicate that children with ADHD symptoms show a delay in the development of automating skills for processing abstract verbal information.     

Perceptual skills of children with developmental coordination disorder

The aim of this study was to investigate whether children with a Developmental Coordination Disorder (DCD) experience problems in the processing of visual, proprioceptive or tactile information. Different aspects of visual perception were tested with the Developmental Test of Visual Perception (DTVP-2), tactile perception was assessed with the Tactual Performance Test (TPT), and a manual pointing task was employed to measure the ability to use visual and proprioceptive information in goal-directed movements. Nineteen children with DCD and nineteen age and sex-matched controls participated in this study. Differences between groups were most pronounced in the subtests measuring visual-motor integration of the DTVP-2, and in two subtests measuring visual perception (visual closure and position in space). On average the children with DCD performed slightly below the norm for tactile perception, with only three children failing the norm. On the manual pointing task, children with DCD made inconsistent responses towards the targets in all three conditions (visual, visual-proprioceptive and proprioceptive condition). No significant differences between groups were found for absolute error. Inspection of the individual data revealed that only two children failed on the majority of perceptual tasks in the three modalities. Across tasks, no consistent pattern of deficits appeared, illustrating the heterogeneity of the problems of children with DCD.     

Attention Problems and Executive Functions in Children With Spina Bifida and Hydrocephalus

This study addressed the incidence of Attention-Deficit/Hyperactivity Disorder (ADHD) subtypes in children with spina bifida meningomyelocele and shunted hydrocephalus (SBH) as well as differences in executive functions among these subtypes. Parent rating scales revealed that 31% of the group with SBH could be identified with AD/HD, mostly the Inattentive type (23%). The group with SBH differed from normal controls on cognitive measures of executive functions, but subtype differences were not significant. Multivariate tests showed that children with SBH were rated with greater difficulties on the Behavior Rating Inventory of Executive Function (BRIEF) compared to controls; those with SBH and any subtype of ADHD differed from those with SBH and no ADHD; and those with ADHD (Combined Type) differed significantly from those with ADHD (Predominantly Inattentive Type). Subtype differences on univariate tests in the latter comparison were significant on the BRIEF Inhibit scale, showing more disinhibition in those with SBH and ADHD (Combined Type), but no significant differences were apparent on the BRIEF Sustain, Shift, and Initiate scales. The results show that the incidence of ADHD in children with SBH exceeds the population rate, is represented by problems with inattention rather than with impulsivity and hyperactivity; and that as with non-brain injured individuals, subtype differences in cognitive function remain to more clearly delineated.     

Attention problems and executive functions in children with spina bifida and hydrocephalus.

This study addressed the incidence of Attention-Deficit/Hyperactivity Disorder (ADHD) subtypes in children with spina bifida meningomyelocele and shunted hydrocephalus (SBH) as well as differences in executive functions among these subtypes. Parent rating scales revealed that 31% of the group with SBH could be identified with AD/HD, mostly the Inattentive type (23%). The group with SBH differed from normal controls on cognitive measures of executive functions, but subtype differences were not significant. Multivariate tests showed that children with SBH were rated with greater difficulties on the Behavior Rating Inventory of Executive Function (BRIEF) compared to controls; those with SBH and any subtype of ADHD differed from those with SBH and no ADHD; and those with ADHD (Combined Type) differed significantly from those with ADHD (Predominantly Inattentive Type). Subtype differences on univariate tests in the latter comparison were significant on the BRIEF Inhibit scale, showing more disinhibition in those with SBH and ADHD (Combined Type), but no significant differences were apparent on the BRIEF Sustain, Shift, and Initiate scales. The results show that the incidence of ADHD in children with SBH exceeds the population rate, is represented by problems with inattention rather than with impulsivity and hyperactivity; and that as with non-brain injured individuals, subtype differences in cognitive function remain to more clearly delineated.     

Preliminary evidence for reduced posterror reaction time slowing in hyperactive/inattentive preschool children

Background: Attention deficit/hyperactivity disorder (ADHD) has been associated with deficits in self-regulatory cognitive processes, some of which are thought to lie at the heart of the disorder. Slowing of reaction times (RTs) for correct responses following errors made during decision tasks has been interpreted as an indication of intact self-regulatory functioning and has been shown to be attenuated in school-aged children with ADHD. This study attempted to examine whether ADHD symptoms are associated with an early-emerging deficit in posterror slowing. Method: A computerized two-choice RT task was administered to an ethnically diverse sample of preschool-aged children classified as either “control” (n = 120) or “hyperactive/inattentive” (HI; n = 148) using parent- and teacher-rated ADHD symptoms. Analyses were conducted to determine whether HI preschoolers exhibit a deficit in this self-regulatory ability. Results: HI children exhibited reduced posterror slowing relative to controls on the trials selected for analysis. Supplementary analyses indicated that this may have been due to a reduced proportion of trials following errors on which HI children slowed rather than due to a reduction in the absolute magnitude of slowing on all trials following errors. Conclusions: High levels of ADHD symptoms in preschoolers may be associated with a deficit in error processing as indicated by posterror slowing. The results of supplementary analyses suggest that this deficit is perhaps more a result of failures to perceive errors than of difficulties with executive control.     

Visuo-Spatial Working Memory Span: A Sensitive Measure of Cognitive Deficits in Children With ADHD

Working memory (WM) has been hypothesised to be impaired in attention-deficit/hyperactivity disorder (ADHD). However, there are few studies reported on tests measuring visuo-spatial WM (VSWM) in ADHD. Some of these studies used paradigms including episodic memory, others only used low memory loads. In the present study we used a VSWM test that has not been used previously in ADHD research. The sensitivity of the VSWM test and a choice reaction time (CRT) test was evaluated in a pilot study by comparing them to two commonly used tests in ADHD-research; the Continuous Performance Test (CPT) and a Go/no-go test, in children with and without ADHD. The groups differed significantly in performance on the VSWM test (P<.01) and CRT (P<.05) but not on the CPT (P>.1) or on the Go/no-go test (P>.1). The results from the VSWM and CRT tests were replicated in a larger sample of participants (80 boys; 27 boys with ADHD and 53 controls, mean age 11.4 years). The difference between the groups was significant for both the VSWM test (P<.01) and the CRT test (P<.01). The effect size (ES) of the VSWM test was 1.34. There was a significant age-by-group interaction on the VSWM test, with larger group differences for the older children (P<.01). Our results show that the VSWM test is a sensitive measure of cognitive deficits in ADHD and it supports the hypothesis that deficits in VSWM is a major component of ADHD.     

Frontal lobe functioning in adolescents with attention deficit hyperactivity disorder

A prominent hypothesis regarding the etiology of attention deficit hyperactivity disorder (ADHD) is that its presence and magnitude reflect frontal lobe dysfunction. Past tests of this hypothesis have been inconsistent. The present study examined frontal lobe functioning in adolescents with ADHD. A sample of 10 ADHD adolescents and 10 controls between the ages of 12 and 17 served as participants for the study. The control group was matched on age (within six months) and gender. This study aided in clarifying past contradictory studies by using clearly defined criteria to determine ADHD, a representative age range of participants, carefully selected tests, and a control task. The two measures that were administered to assess frontal lobe functioning were the Wisconsin Card Sorting Test and the Stroop Color and Word Test. The Purdue Pegboard was used as a control measure that did not assess frontal lobe functioning. The findings indicate that the ADHD group performed significantly worse on the following: color score, color/word score, and interference score of the Stroop Color and Word Test; percent of perseverative responses, percent of perseverative errors, and number of completed categories of the Wisconsin Card Sorting Test. No differences were found on the Purdue Pegboard task.     

Effects of Symptoms of ADHD, ODD, and Cognitive Functioning on Social Acceptance and the Positive Illusory Bias in Children

Objective: To examine the effects of symptoms of ADHD and ODD and cognitive functioning on social acceptance and positive bias in children. Method: The sample consisted of 86 children (49 girls) between 7 and 13 years old, recruited to reflect a wide range of ADHD symptoms. Parents and teachers reported on ADHD and ODD symptoms and social acceptance. Children reported on social acceptance and were given tasks measuring working memory, inhibition and reaction-time variability. A discrepancy score between child and adult reports of social acceptance was used as a measure of positive bias. Results: Inattention independently explained variance in social acceptance. The cognitive factors were related to social acceptance and the positive bias, but not beyond the ADHD and ODD symptoms. Conclusion: It is primarily disruptive behavior that contributes to external reports of children's social acceptance.     

Response Style Differences in the Inattentive and Combined Subtypes of Attention-Deficit/Hyperactivity Disorder

This study examined potential differences between the inattentive and combined ADHD subtypes using laboratory tasks assessing behavioral inhibitory processes. Seventy-five children completed two tasks of behavioral inhibition believed to isolate different processes: the cued reaction time task (CRT), a basic inhibition task, and the go/no-go task (GNG), a complex inhibition task that incorporates motivational contingencies. Three groups of participants were identified, including ADHD/Inattentive (n = 17), ADHD/Combined (n = 37), and comparison (n = 21). Results indicated that rather than showing behavioral inhibition deficits, the ADHD/I children appeared overly inhibited, as evidenced by slower reaction times across the two tasks and significantly higher errors of omission in the GNG task. Additionally, the ADHD/I children did not demonstrate cue dependency effects on the CRT task, suggesting that they were failing to incorporate relevant information before making a response. The sluggish and inhibited performance of the ADHD/I group challenges the idea that it is a subtype of ADHD.     

Practice effects on visuomotor and problem-solving tests by children

Practice effects on a visuomotor test (the Developmental Test of Visuo-Motor Integration), a timed visual discrimination test (the Underlining Test), and two problem-solving tests (the Porteus Mazes Test and the Tower of Hanoi Test) were analyzed. Children of two age groups (Ms: 7.7 and 11.6 yr.) were chosen to study the effect of age on practice effects. The tests were repeated nine times with test-retest intervals of 2 mo. The Developmental Test of Visuo-Motor Integration showed no practice effects, while the Porteus Mazes Test, the Underlining Test, and the Tower of Hanoi Test showed significant practice effects. Practice effects were larger for the older age group on all the tests, except the Developmental Test of Visuo-Motor Integration. The Developmental Test of Visuo-Motor Integration and the Underlining Test showed good reliability, but those of the problem-solving tasks were less satisfactory. The stability of all the tests, except the Tower of Hanoi Test, was good.     

Cognitive estimations as a measure of executive dysfunction in childhood epilepsy

Children and adolescents with epilepsy are known to demonstrate executive function deficits. Despite prior work that has shown that cognitive estimation tasks are sensitive to executive dysfunction in children, such tasks have not been studied in children with epilepsy. This is particularly important given the fact that executive tasks have heretofore shown poor ecological validity, and it has been speculated that estimation tasks may show stronger ecological validity than other executive tests. One hundred and thirteen clinically referred children and adolescents with epilepsy were included. The Biber Cognitive Estimations Test was sensitive to cognitive dysfunction, with about half showing impairments on this task in comparison to age-matched normative data; the most frequently impaired subscales were quantity estimation and time estimation. Moreover, the Biber Cognitive Estimation Test showed moderate correlations with not only overall intellectual functions and academic achievement but also other commonly administered tests of executive functions, including digit span, Trailmaking, and the Tower of London but not with the contingency naming test. Cognitive estimations were also modestly correlated with age of epilepsy onset but not other epilepsy-severity variables such as number of antiepilepsy drugs (AEDs) or seizure frequency. Unfortunately, the hypothesis that the Biber Cognitive Estimation Test would show strong ecological validity was not supported, as it showed weak relations with parent-reported executive function deficits. The significance and limitations of this investigation are discussed.     

Time Reproduction in Children With ADHD: Motivation Matters

The primary goal of this study was to examine whether children with ADHD have a true deficit in subjective time sense, or whether their impairment reflects a motivational deficit. Thirty children with ADHD and 30 matched control children completed two versions of a time reproduction paradigm (“Regular” and “Enhanced”) in which motivational level was manipulated by the addition of positive sham feedback and the prospect of earning a reward. A secondary goal was to investigate performance on measures of working memory and behavioural inhibition, and how those constructs relate to time reproduction in the context of Barkley’s (1997a) model of ADHD. Children with ADHD performed significantly better on the motivating ‘Enhanced’ versus the Regular time reproduction paradigm, although they continued to perform significantly worse than controls on both tasks. Control children exhibited no reliable change in performance between versions of the task. Significant group differences were also observed on the working memory and behavioural inhibition tasks. We discuss the impact of motivation, working memory, and behavioural inhibition on time reproduction performance.