Cognitive event-related potentials in attention deficit disorder

Cognitive event-related potentials (ERPs) have been used to aid in the interpretation of findings that children with Attention Deficit Disorder (ADD) make more errors and react more slowly than nondisabled controls in tests of sustained attention. Coincident with their abnormally poor performance, children with ADD have smaller late positive components of the ERP (especially a wave known as P3b) than their peers with psychiatric diagnoses. Notably, stimulant administration improves the performance of children with ADD and enlarges the amplitude of the late positive waves of their ERPs. These findings are interpreted as reflecting reduced capacity allocation, which, in turn, is increased by stimulant medications. Research on memory scanning suggests that children with ADD are deficient in energetic aspects of information processes and that their excessive slowness in reaction time tests involves stages following memory search and decision, that is, motor processes. The same factors seem to be involved in the amelioration of performance by stimulants, which speed up motor responses but do not affect the latency of P3b. Research on ERPs during selective attention also points to possible disturbances in this aspect of processing, but further research in this area is needed.     

Attention deficit disorder and specific reading disability: separate but often overlapping disorders

Within a large (N = 182) heterogeneous sample of clinic-referred children with DSM-III-diagnosed attention deficit disorder (ADD), three behavioral subgroups were identified via cluster analysis of teacher ratings: 40% of the children had ADD with hyperactivity (ADDH), 30% had ADD with hyperactivity and aggressivity (ADDHA), and 31% had ADD without hyperactivity or aggressivity. Proportionally more girls were in the ADD-only subgroup. Over half the sample (n = 94) were poor readers, with 82 meeting discrepancy criteria for specific reading disability (RD). Proportionately more boys than girls met the RD criteria (9.2:1.0), whereas the sex ratio of males to females for the whole sample was 5.1 to 1.0. Focusing just on white males, the three behavioral subgroups were significantly different on convergent validity measures, such as other teacher ratings, parent ratings, and interview-elicited ratings of externalizing behavior, but were not different on such divergent validity measures as IQ and achievement scores, self-ratings, and laboratory performance tasks. Boys in the ADD sample who did not meet criteria for RD had significantly higher IQs than those who did, but subgroups with and without RD still differed significantly on WRAT-R reading and spelling scores with IQ covaried out. Both groups with and without RD could be differentiated from a control group on laboratory measures of sustained attention and impulse control. Methylphenidate benefited all subgroups equally, whether RD or not, and whether given a low (0.3 mg/kg) or high (0.6 mg/kg) dose.     

The boundaries of attention deficit disorder

This report examines distinctions and interrelationships among attention deficit disorder (ADD) and two closely related conditions: learning disability (LD) and oppositional/conduct (O/C) disorder. To evaluate our hypothesis that some of the difficulty in resolving the relationship between ADD and, particularly, O/C may reflect the consequences of selective referral patterns, we studied groups of children diagnosed as ADD from different referral sources. Results suggest that referral bias does exist and that children referred to mental health settings differ from those referred to pediatricians, child neurologists, or psychologists. Because of the nature of the subjects referred to mental health services, nonrepresentative associations may emerge. Rather than being considered as prototypical of all children with attention disorder, children referred to mental health facilities may represent simply an extreme of the continuum of ADD. Evidence suggests that many children with ADD will be represented by those referred primarily for attentional deficits and learning problems, rather than those with inattention, hyperactivity, or aggression referred for child psychiatric evaluation.     

Information processing deficits in children with attention-deficit/hyperactivity disorder, inattentive type, and children with reading disability

We examined the information processing capabilities of children diagnosed with the inattentive subtype of attention-deficit/hyperactivity disorder (ADHD) who had been characterized as having a sluggish cognitive tempo. Children referred for school-related problems (n = 81) and nonreferred community controls (n = 149) participated. Of the referred children, 24 met criteria for ADHD, 42 met criteria for reading disability (RD), and 9 of these were comorbid for RD and ADHD. Children with ADHD differed from those without ADHD on a visual search task but not on an auditory processing task; the reverse was true for children with RD. Decomposition of the visual search task into component operations demonstrated that children in the ADHD group had a slow processing rate that was not attributable to inattention. The children with ADHD were not globally poor at information processing or inattentive, but they demonstrated diminished speed of visual processing.     

Taxonomic separation of attention deficit disorders and developmental reading disorders

This investigation compared the behavior ratings and psychometric profiles of children with attention deficit disorders (ADD) and children with developmental reading disorders (DRD). ADD children showed no qualitative reading or spelling problems, although they were slightly behind expected levels of academic achievement. DRD children were significantly more impaired in academic attainment and showed evidence of qualitative disturbances in reading and spelling. DRD subjects did not differ from control subjects on ratings of hyperactivity, which was one of the defining variables of the ADD group. This evidence is interpreted as adding to a growing testimony that indicates that ADD and DRD are distinctly separate groups of disorders.     

The etiological relationship between reading disability and phonological disorder

The present study investigated the etiological relationship between two disorders: dyslexia or reading disability (RD) and phonological disorder (PD). These disorders manifest at different ages and have typically been studied by researchers in different disciplines. However, a growing body of evidence suggests that the disorders overlap at symptomatic, cognitive, and etiological levels of analysis. In previous studies, each disorder has been found to be heritable, and there is also evidence that RD and PD run together in families, but no studies to date have documented whether there is a shared genetic influence between the two disorders. The present study examined this question in a sample of RD and non-RD twins. Subjects with a history of PD were identified and the etiological relation between the two disorders was examined. Results indicated that in the present sample, RD and PD are each heritable on their own. Further, even when correcting for RD, the two disorders were found to be coheritable, indicating that the finding of cofamiliality of RD and PD is at least partially driven by genetic influences. The implications of these results for the conceptualization, identification, and treatment of these two disorders are discussed.     

Cognitive mechanisms underlying achievement deficits in children with mathematical learning disability

Using strict and lenient mathematics achievement cutoff scores to define a learning disability, respective groups of children who are math disabled (MLD, n=15) and low achieving (LA, n=44) were identified. These groups and a group of typically achieving (TA, n=46) children were administered a battery of mathematical cognition, working memory, and speed of processing measures (M=6 years). The children with MLD showed deficits across all math cognition tasks, many of which were partially or fully mediated by working memory or speed of processing. Compared with the TA group, the LA children were less fluent in processing numerical information and knew fewer addition facts. Implications for defining MLD and identifying underlying cognitive deficits are discussed.     

Why the timing deficit hypothesis does not explain reading disability in adults

It has been proposed that the phonological coredeficit that is linked to reading failure hasas its underlying cause a deficit in temporalprocessing. In a multivariate investigationdesigned to examine the temporal processingdeficit hypothesis, thirty reading-disabled(RD) adults, thirty-two normally achievingadults and thirty-one normally achievingchildren (reading-level controls) wereadministered a comprehensive battery thatincluded a wide range of timing tasks, inaddition to reading and phonological measures. Although adults with RD displayed overallperformance that was below that of normallyachieving adults on most of the timing tasks,their performance was not differentiallyinfluenced by rate of stimulus presentation. Although the RD adults displayed the typicalpattern of impaired phonological awareness andpseudoword reading relative to reading-levelmatched children, the reading-disabled adultsoutperformed the children on the timing tasks. Finally, with the exception of continuousnaming, the timing tasks shared little variancewith phonological sensitivity and contributedlittle unique variance to word reading. Although these findings undermine the timingdeficit hypothesis, they do provide evidencefor the involvement of naming deficits inreading disability.     

Separating genuine cases of reading disability from reading deficits caused by predominantly inattentive ADHD behavior

Conventional methods of differentiating reading disability (RD) caused by deficits in decoding skills or comprehension from poor reading performance caused by inconsistent attention associated with attention-deficit/hyperactivity disorder (ADHD) have produced equivocal results. This study presents a model of differential diagnosis of attentional problems and RD that differs from these conventional approaches. The new diagnostic procedure uses intraindividual differences seen in the performance of at-risk learners on tasks related to reading that vary in their sensitivity to the sustained attention required for successful performance. The hypothesis is that children with inconsistent attention would perform more poorly on tests that require sustained attention, such as listening comprehension, than on tests that are more tolerant of inattention, such as reading comprehension. Such differences would not be seen in the test scores of children who have only RD, because their performance is determined more by the difficulty level of the reading tests than by the degree of sensitivity of the task to attention. The validity of this new model was evaluated by determining the capability of the differences seen in the scores of tests that differ in their sensitivity to sustained attention to predict the degree of inconsistency in sustained attention as measured by a continuous performance test. The data obtained from 39 children who are at risk for RD suggest that this is a viable model.     

Remediating the core deficits of developmental reading disability: a double-deficit perspective

The double-deficit hypothesis (Wolf, 1997; Wolf & Bowers, 1999, this issue) contends that deficits in phonological awareness and deficits in visual naming speed represent two independent causal impediments to reading acquisition for children with developmental reading disabilities (RD). One hundred and sixty-six children with severe RD from 7 to 13 years of age were classified into three deficit subgroups according to a double-deficit framework. A total of 140 children with RD, 84% of the sample, were classified; 54% demonstrated a double deficit (DD), 22% a phonological deficit only (PHON), and 24% a visual-naming speed deficit only (VNS). Diagnostic test profiles highlighted the joint contributions of the two core deficits in depressing written language acquisition. The children in the DD group were more globally impaired than those in the other subgroups, and the VNS group children were the highest achieving and most selectively impaired readers. Following 35 hours of word identification training, sizable gains and significant generalization of training effects were achieved by all subgroups. A metacognitive phonics program resulted in greater generalized effects across the domain of real English words, and a phonological training program produced superior outcomes within the phonological processing domain. The greatest non-word reading gains were achieved by children with only phonological deficits.     

Experimental training of children with attention deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder （AD/HD） negativelly affects the cognitive and psychomotoric spheres of the pupil＇s social behavior and social adaptation. The review of many studies states that pupils with AD/HD achieve worse learning results because of insufficiently functioning cognitive processess, such as attention, （work） memory, thinking, problem solving, language, small- and large- scale motorics. Behavioral features, exhibited with AD/HD, include low-frustration tolerance, temper problems, persistence, emotional liability, depression, peer rejection, poor self-concept and poor self-esteem. Because of insufficiency of the cognitive processes, the difficulties of social behavior and social adaptation, pupils with AD/HD more often have a dysfunction of pupils＇ role that manifests by learning difficulties and behavior problems. The manifestation of the disorder in the younger school age in the context of children＇s school activities and roles actualizes the exceptional interest of the educational science in the analyzed phenomenon. The search and construction of effective means of socio-educational help for AD/HD primary class pupils should be associated with coordination and adaptation of different effective educational methodologies of different conceptual origin. In order to develop cognitive, psycho-motoric abilities and social behavior of the group of primary class pupils with AD/HD （N=22）, activities of supplementary education were organized after classes （their duration was 6 months）. During the forming experiment, original methodologies were constructed and national and foreign researchers＇ educational methodologies were adapted and tested in new, specific conditions （methods of fairy-tales, correction of cognitive behavior, graphical-logical tasks, games in the sport hall）. Even by relatively rare activities of supplementary education in a homogeneous group of children suffering from AD/HD positive changes of cognitive, psychomotoric sphere, social behavior and social adaptation were achieved.     

Occurrence and pattern of impaired reading and written language in children with attention deficit disorders

The purpose of this study was to investigate the occurrence and severity of reading, spelling, and written language impairment in children clinically referred for Attention Deficit Hyperactivity Disorder (ADHD). Specific questions involved 1) whether ADD subgroups with and without hyperactivity differ in reading, spelling, and written language achievement, 2) whether age and gender interact with ADD sub-group class to affect reading/written language achievement, and 3) whether prevalence of impaired reading/written language in these subgroups is consistent with previous reports in heterogeneous samples. Subjects were 115 ADD children aged 6-12 who were subclassified as ADD + H(72 percent) and ADD - H(28 percent) by objective teacher ratings. Dependent measures included tests of single word recognition and vocabulary, word attack, contextual comprehension, written spelling, written sentence construction, and writing fluency, in addition to a structured behavioral observation, during which aspects of inattention and motor activity were coded. A large fraction of this sample met public school LD criteria (54 percent), and achievement on most measures was globally poorer than the respective test normative groups. The ADD + H subgroup showed significantly poorer word attack skills, while the subgroups did not significantly differ from each other on other reading/written language measures. However, 17 percent of the total ADD sample were ≥ 1.5 SD below the mean in total reading achievement, and 29 percent were ≥ 1.5 SD below the mean on measures of written spelling/language. Gender X age interactions, indicating poorer performance in the middle age group of females, were likely related to lower IQ.     

Genetic etiology of spelling deficits in the Colorado and London twin studies of reading disability

The basic multiple regression model for the analysis of selected twin data (DeFries and Fulker 1985, 1988) was fitted to spelling data from 100 pairs of MZ twins and 71 pairs of same-sex DZ twins tested in the Colorado Reading Project (DeFries, Olson, Pennington and Smith 1991), and to data from 12 pairs of MZ twins and 15 pairs of same-sex DZ twins tested in the London twin study of reading disability (Stevenson, Graham, Fredman and McLoughlin 1984, 1987). Estimates of h _g ² obtained from analyses of these data suggest that about 60% of the deficit of probands is due to heritable influences in both samples. When a regression model was fitted separately to data from males and females in the combined Colorado and London samples, resulting estimates of h _g ² were 0.66±0.18 and 0.56±0.19, respectively, a nonsignificant difference. Collaborative analyses of data from additional twin studies of reading disability would facilitate more rigorous tests of hypotheses of differential genetic etiology as a function of group membership.     

Task performance and response to frustration in children with attention deficit hyperactivity disorder

The present study examined performance on an arithmetic task of increasing difficulty and a frustrating puzzle task for children with ADHD and comparison children. Emotional competence also was investigated in the two groups. Sixty‐four children, 21 previously diagnosed with ADHD, participated. Performance on the arithmetic task was measured in terms of completion and accuracy. Children with ADHD had similar rates of accuracy for all levels of difficulty, but completed fewer problems. Performance on the puzzle task was measured both through completion and persistence. Although children with ADHD persisted for a similar amount of time compared to children without ADHD, they were more likely to quit the task before completion. Children with ADHD also were more likely to report that they became frustrated with the task. Furthermore, they tended to report that in general, they become more frustrated than other children. With regard to emotional competence, children with ADHD did not differ from the comparison children on their reported understanding of their own emotions or attention to emotions; however, children with ADHD reported that they engage in less mood repair. © 2006 Wiley Periodicals, Inc. Psychol Schs 43: 377–386, 2006.     

First impressions formed of boys with learning disabilities and attention deficit disorder

The present study examined the first impressions that are formed of boys with either learning disabilities (LD), attention deficit disorder (ADD), or both disorders, in an effort to understand better why they are so often unpopular with and rejected by their peers. The intent of the study was to remedy methodological problems of previous first-impression studies to determine whether devaluation of boys with either LD or ADD after a brief exposure is a reliable and valid finding. To this end, physical attractiveness data were gathered, children were employed as judges, subgroups of stimulus children were formed, and situational demands were varied. Results indicated that the boys with either LD or ADD were devalued relative to controls on a variety of dependent variables, including popularity. Both situational demands, as well as judgments of physical attractiveness, appeared to play a role in accounting for these differences.     

Reflections on research on reading disability with special attention to gender issues

This commentary reviews some of the issues involved in the definition of reading disability and demonstrates how definitions can influence the conclusions reached by a review. In particular, the discrepancy definition of reading disability is shown to be logically flawed. Data from a large unbiased sample show that there are no significant differences between boys and girls in the incidence of reading difficulties.