Interrelationships between Reading Disability and Attention-Deficit/Hyperactivity Disorder

Planum temporale morphology in children with developmental dyslexia

The planum temporale is a highly lateralized cortical region, located within Wernicke's area, which is thought to be involved in auditory processing, phonological processing, and language. Research has linked abnormal morphology of the planum temporale to developmental dyslexia, although results have varied in large part due to methodological inconsistencies in the literature. This study examined the asymmetry of the planum temporale in 29 children who met criteria for dyslexia and 26 children whose reading was unimpaired. Leftward asymmetry of the planum temporale was found in the total sample and this leftward asymmetry was significantly reduced in children with dyslexia. This reduced leftward asymmetry in children with dyslexia was due to a planum temporale that is larger in the right hemisphere. This study lends support to the idea that planum temporale asymmetry is altered in children with developmental dyslexia.

Gaps-in-noise (GIN©) test results in children with and without reading disabilities and phonological processing deficits

OBJECTIVE

To determine if the gaps-in-noise (GIN(©)) test could differentiate children with dyslexia and significant phonological awareness deficits from a group of children with normal reading skills.

DESIGN

A prospective study of GIN test performance in two groups of children. Participants were administered routine audiological tests, a phonological processing test, and an auditory temporal resolution test (GIN test). Statistical testing was completed to determine if significant differences existed between groups on GIN test results and phonological processing measures, and to examine potential relationships between these test measures. Routine clinical analysis procedures examined the performance of the two groups from a clinical perspective.

STUDY SAMPLE

Participants included 61 children between the ages of 8 years, 1 month and 9 years, 11 months, separated into two groups: children with dyslexia and significant phonological deficits (Group I); normal-reading peers with age-appropriate phonological skills (Group II).

RESULTS

Children in Group I showed longer gap detection (GD) thresholds and lower gap identification scores than did the children in Group II. Results of statistical and clinical testing revealed significant differences between the groups.

CONCLUSION

An auditory temporal processing deficit is a factor to be considered in children presenting with dyslexia and phonological processing disorders.

Reading fluency: implications for the assessment of children with reading disabilities

The current investigation explored the diagnostic utility of reading fluency measures in the identification of children with reading disabilities. Participants were 50 children referred to a university-based clinic because of suspected reading problems and/or a prior diagnosis of dyslexia, where children completed a battery of standardized intellectual, reading achievement, and processing measures. Within this clinical sample, a group of children were identified that exhibited specific deficits in their reading fluency skills with concurrent deficits in rapid naming speed and reading comprehension. This group of children would not have been identified as having a reading disability according to assessment of single word reading skills alone, suggesting that it is essential to assess reading fluency in addition to word reading because failure to do so may result in the under-identification of children with reading disabilities.

[Deficits in reading acquisition in primary school: cognitive, social and behavioral factors studied in a sample of 1062 children]

BACKGROUND

Reading impairment is the major learning disability in children. While research on illiteracy has mainly been conducted from a sociological perspective, research on dyslexia has typically been studied from a cognitive-linguistic perspective. Studies that jointly investigate sociological, behavioral and cognitive factors in predicting reading outcome are rare and limited to English-speaking populations. The goal of the present study was to screen second grade children with reading impairment in French urban elementary schools and to pin down the factors that explain the various facets of reading failure and success.

METHODS

A total of 1062 children from 20 different schools in the city of Paris participated in the study. Different aspects of reading were assessed individually for children with a suspected impairment in reading acquisition. Subsequently, 131 poor readers and 50 typically developing readers were matched for sex, age, and school. For these children, medical, cognitive, behavioral and individual socioeconomic data were obtained. Group differences were examined and multiple regression analyses were conducted to examine how much variance in reading was explained by the various variables.

RESULTS

The prevalence of poor reading skills in grade 2 was highly influenced by neighborhood socioeconomic status (SES) (ranging from 3.3% in high SES to 20.5% in low SES areas). Among the SES variables, employment of the father was a significant predictor of poor reading. Among the cognitive variables, phonological awareness and rapid naming were the most significant factors, much more than verbal or nonverbal intelligence. Among the behavioral variables, attention was an important factor but not externalized symptoms. Multiple regression analyses showed that reading outcome was best predicted by phonological awareness skills and attention deficits.

CONCLUSION

The majority of children with reading disability come from low SES areas. As in the English literature, the most robust predictor for reading impairment is phonological awareness, even when SES is taken into account. In addition, attention deficits seemed to aggravate reading impairments for children with weak phonological awareness skills. Successful early prevention should focus on reinforcing phonological awareness, recoding and attention skills.

Learning, attention, writing, and processing speed in typical children and children with ADHD, autism, anxiety, depression, and oppositional-defiant disorder

Learning, attention, graphomotor, and processing speed scores were analyzed in 149 typical control children and 886 clinical children with normal intelligence. Nonsignificant differences were found between control children and children with anxiety, depression, and oppositional-defiant disorder. Control children performed better than children with ADHD and autism in all areas. Children with ADHD and autism did not differ, except that children with ADHD had greater learning problems. Attention, graphomotor, and speed weaknesses were likely to coexist, the majority of children with autism and ADHD had weaknesses in all three areas, and these scores contributed significantly to the prediction of academic achievement.

Phonological short-term memory and central executive processing in attention-deficit/hyperactivity disorder with/without dyslexia – evidence of cognitive overlap

Attention-deficit/hyperactivity disorder (ADHD) with/without dyslexia was investigated using a double dissociation design. Neuropsychological performance representing the core deficits of the two disorders was measured in order to test the common deficit hypothesis. Phonological short-term memory, morpho-syntactical language, and central executive processing (manipulating and switching) tasks were administered to four groups of 10-14 year old children (ADHD-only n = 20, dyslexia-only n = 20, ADHD+dyslexia n = 20, and controls n = 19). Comparisons of performance on these tasks were carried out using 2 (ADHD yes/no) x 2 (dyslexia yes/no) factorial analyses of variance and covariance. Significant main effects were found for dyslexia (language processing functions) and for ADHD (EF switching). In the case of the EF manipulating a main effect for both dyslexia and ADHD was revealed. Effect sizes of mean performance indicated that all three impaired groups shared a common deficit in working memory which could reflect a cognitive overlap partly explaining the high rate of co-occurring dyslexia and ADHD.

Management of dyslexia, its rationale, and underlying neurobiology

Developmental dyslexia is characterized by an unexpected difficulty in reading in children and adults who otherwise possess the intelligence and motivation considered necessary for accurate and fluent reading. Dyslexia is the most common and most carefully studied of the learning disabilities, affecting 80% of all individuals identified as learning disabled. Although in the past the diagnosis and implications of dyslexia were often uncertain, recent advances in the knowledge of the epidemiology, the neurobiology, the genetics, and the cognitive influences on the disorder now allow the disorder to be approached within the framework of a traditional medical model. This article reviews these advances and their implications for the approach to patients presenting with a possible reading disability.

Error-related event-related potentials in children with attention-deficit hyperactivity disorder, oppositional defiant disorder, reading disorder, and math disorder

We studied error-related negativity (ERN) and error positivity (Pe) during a discrimination task in 319 unmedicated children divided into subtypes of ADHD (Not-ADHD/inattentive/combined), learning disorder (Not-LD/reading/math/reading+math), and oppositional defiant disorder. Response-locked ERPs contained a frontocentral ERN and posterior Pe. Error-related negativity and positivity exhibited larger amplitude and later latency than corresponding waves for correct responses matched on reaction time. ADHD did not affect performance on the task. The ADHD/combined sample exceeded controls in ERN amplitude, perhaps reflecting patients' adaptive monitoring efforts. Compared with controls, subjects with reading disorder and reading+math disorder performed worse on the task and had marginally more negative correct-related negativities. In contrast, Pe/Pc was smaller in children with reading+math disorder than among subjects with reading disorder and Not-LD participants; this nonspecific finding is not attributable to error processing. The results reflect anomalies in error processing in these disorders but further research is needed to address inconsistencies in the literature.

Processing speed deficits in attention deficit/hyperactivity disorder and reading disability

The goal of the current study was to test whether deficits in processing speed (PS) may be a shared cognitive risk factor in reading disability (RD) and Attention Deficit/Hyperactivity Disorder (ADHD), which are known to be comorbid. Literature on ADHD and RD suggests that deficits on tasks with a speeded component are seen in both of these disorders individually. The current study examined a wide range of speeded tasks in RD, ADHD, comorbid RD+ADHD, and a control group to test whether RD and ADHD have similar profiles of PS deficits, and whether these deficits are shared by the two disorders. The results suggest that a general PS deficit exists in both clinical groups compared to controls, although children with RD demonstrate greater PS deficits than children with ADHD. Two tests (underadditivity and partial correlations) were conducted to test whether these PS deficits are shared. Since we found that PS deficits were underadditive in the comorbid group and that partialling PS reduced the correlation between RD and ADHD, it appears that PS is a shared cognitive risk factor that may help explain the comorbidity of these two disorders.

Neuropsychological functioning in people with ADHD across the lifespan

ADHD is defined by behavioral characteristics similar to neuropsychological disorders of executive dysfunction. This paper is a literature review of the neurocognitive characteristics of ADHD from early childhood through adulthood. The author addresses the development of the concept of attention and executive function (EF) deficits in ADHD, clinical neuropsychological studies of pre-teenage children, teenagers and adults with ADHD, gender and the role of psychiatric co-morbidity including the relationship of learning disabilities to ADHD, heterogeneity of neuropsychological dysfunctions, experimental neuropsychological studies, the relationship of brain structure to function, psychopharmacology of ADHD, and clinical neuropsychological assessment. The group data clearly supports the hypothesis that executive dysfunctions are correlates of ADHD regardless of gender and age, and these EF deficits are exacerbated by co-morbidity with learning disabilities such as dyslexia. However, there is limited data on children under the age of 5, teenagers from age 13-18, and adults with ADHD over the age of 40. Studies of individual classification of people with ADHD compared to healthy, non-psychiatric controls do not support the use of neuropsychological tests for the clinical diagnosis of ADHD, and indicate that not all persons with ADHD have EF deficits. Some persons with ADHD may have deficits in brain reward systems that are relatively independent of EF impairments. Future research should clarify the multiple sources of ADHD impairments, continue to refine neuropsychological tools optimized for assessment, and incorporate longitudinal, developmental designs to understand ADHD across the lifespan.

ADHD and dyscalculia: Evidence for independent familial transmission

The familial relationship between dyscalculia and attention-deficit/hyperactivity disorder (ADHD) was assessed. We conducted a familial risk analysis using probands with and without ADHD of both genders and their first-degree relatives. Participants were assessed with structured diagnostic interviews and a cognitive test battery. We found elevated rates of ADHD in relatives of both ADHD proband groups, regardless of dyscalculia status, and elevated rates of dyscalculia in relatives of probands with dyscalculia, irrespective of ADHD status. There was no evidence for cosegregation or assortative mating. Our findings support the hypothesis that ADHD and dyscalculia are independently transmitted in families and are etiologically distinct. These results reinforce the current nosological approach to these disorders and underscore the need for separate identification and treatment strategies for children with both conditions.

Neuropsychological function in adults with attention-deficit/hyperactivity disorder

This article reviews the current state of the literature pertaining to the neuropsychological dysfunctions that are found in children and adults with attention-deficit/hyperactivity disorder (ADHD). Be-cause considerable controversy has existed about the nature and validity of adult ADHD, this article will aid clinicians in develop-ing a better understanding of the empirical literature on neuropsychological function in ADHD throughout the lifespan.

ADHD and reading disability in male adults: is there a connection?

The present study examined the comorbidity between attention-deficit/hyperactivity disorder (ADHD) and reading disability (RD) in male adults. Participants were 120 men, of whom 24 were classified as having ADHD. The basis for the diagnosis was two self-report scales validated by interviews and background data. An extensive battery was used to assess phonological abilities and various aspects of reading skills. No differences were obtained between adults with and without ADHD on measures of either phonological processing skills or word decoding, indicating a low comorbidity with RD. This finding was valid even when different criteria were used to diagnose RD. However, the two groups differed in reading comprehension, with individuals with ADHD performing poorly in tests of reading comprehension. These results are compatible with the view that reading comprehension involves many of the higher cognitive control functions assumed to be impaired in ADHD. However, these attentional control functions are not critical to word recognition, which is determined by a more encapsulated phonological processing module. The pattern of associations between ADHD and RD observed in the present study is explained with reference to the differential attentional demands of the two aspects of reading.

The developmental course of processing speed in children with and without learning disabilities

This study contrasted the development of processing speed in children with and without learning disabilities. We examined whether the same global mechanism presumed to be responsible for the normal developmental improvement in processing speed might also be associated with the processing speed deficiencies observed in children with learning impairments. One hundred and twenty-two children with learning disabilities in reading and/or math and 206 non-disabled community controls participated. There were no differences in relation of age to the development of processing speed for children with and without learning disabilities. We interpreted these results as suggesting that the underlying etiologies for the normal developmental change in processing speed and for the relative deficiencies in processing speed seen among children with learning disabilities were different.

Evidence for unexpected weaknesses in learning in children with attention-deficit/hyperactivity disorder without reading disabilities

This study examined the mechanisms underlying verbal learning in children with and without attention-deficit/hyperactivity disorder (ADHD), none of whom had reading disabilities. Children with ADHD were compared to typically developing children on both process and product scores from the California Verbal Learning Test for Children. The findings indicated that children with ADHD initially learned the same number of words as controls but showed weaknesses recalling the words after delays, suggesting that children with ADHD are less efficient learners. Regardless of ADHD status, boys and girls performed differently. Boys used semantic clustering less frequently and recalled fewer words from the middle region of the list than girls; girls also outperformed boys in terms of overall performance, despite lower verbal IQ scores. These findings show that children with ADHD can exhibit unexpected weaknesses in learning even without a formal learning disability. Gender differences in verbal learning are also illustrated.

Fronto-central dysfunctions in reading disability depend on subtype: guessers but not spellers

The goal of this study was to test the hypothesis that the inhibitory deficits previously found in children with the guessing subtype of dyslexia (who read fast and inaccurately) can be attributed to dysfunctions in the fronto-central brain areas. For this purpose, the electrocortical correlates of the inhibition mechanism were assessed in a stop task that was adapted for event-related brain potential recording. It was found that in children with the spelling subtype of dyslexia (who read slowly and accurately) and normal readers, a positive component with a fronto-central scalp distribution was related to processes engaged in the inhibition of a response. Guessers did not show this "inhibition P300." Analyses of the lateralized readiness potential (LRP) data suggested that response inhibition in spellers depended (at least in part) on their ability to inhibit the central activation of the response. In guessers, the association between response inhibition and inhibition of activity in the central motor structures was found to be weaker. It was concluded that the inhibitory deficits in guessers can be attributed to dysfunctions in the fronto-central brain structures involved in selective motor inhibition (indicated by the LRP data) and nonselective motor inhibition (indicated by the P300 data). It was suggested that there may be an association between guessers and attention deficit hyperactivity disorder children in that both clinical groups may suffer from the same type of deficits in executive functioning.

Effects of event probability and sequence on children with attention-deficit/hyperactivity, reading, and math disorder

BACKGROUND

We investigated the impact of stimulus probability and sequence on performance and event-related potentials of 310 children classified into 12 combinations of attention-deficit/hyperactivity disorder (Not-attention-deficit/hyperactivity disorder, Inattentive and Combined subtypes) with presence/absence of reading disorder and math disorder.

METHODS

Subjects pressed buttons to displays of the letters O and X, which were presented with probabilities of either .17/.83 or .50/.50. Greater response selection was required in the .17/.83 condition.

RESULTS

Stimulus probability had comparable effects on all diagnostic groups. The extent of mismatch between a stimulus and preceding events elicited less systematic increases in errors, P3b latency, and P3b amplitude among both attention-deficit/hyperactivity disorder subtypes than controls. Mismatch with preceding trials more greatly reduced math disorder and reading disorder + math disorder children's speed in the Rare task and accuracy in both conditions. Math disorder and reading disorder + math disorder subjects also registered less the effects of alternations of the infrequent O on N2 amplitude and on P3b latency.

CONCLUSIONS

Math disorder and reading disorder + math disorder youngsters' lower sensitivity to sequence irregularity in their event-related potentials along with greater disruption of performance suggest working memory deficits that adversely affected response selection. Comorbidity of attention-deficit/hyperactivity disorder and reading disorder did not affect the results.

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.

Validity of the Brown ADD scales: an investigation in a predominantly inattentive ADHD adolescent sample with and without reading disabilities

The Brown ADD Scale for Adolescents is widely used in clinical settings, yet, no published studies have investigated divergent and concurrent validity and specificity and sensitivity to inattentive ADHD symptomatology. Ninety-eight participants (13 to 16 years) were classified as ADHD/I and/or reading disabled (RD) using Kiddie Schedule for Affective Disorder and Schizophrenia (K-SADS), Conners' Rating Scales (CRS-R), and Ontario Child Health Study Scales (OCHSS), WRAT3, and WRMT-R. The results were: 29 ADHD/I; 12 RD, 16 ADHD/I with RD; and, 41 controls. The RD group was included to evaluate specificity. The Brown was administered but not used in classification. The ADHD groups scored higher on the Brown subscales compared with the other two groups. The recommended cutoffs resulted in high rates of false negatives but few false positives; this suggests good specificity but poor sensitivity. There were moderate correlations among the Brown, CRS-R, and OCHSS. The Brown can be useful in screening out ADHD; however, its low sensitivity precludes its usefulness in diagnosing ADHD.

The term comorbidity is of questionable value in reference to developmental disorders: data and theory

Over the last decade, there has been an enormous increase in the number of studies evaluating the overlap of developmental syndromes or disorders in both children and adults. This overlap of symptoms is often referred to as comorbidity, a term we criticize in this article because of its unsubstantiated presumption of independent etiologies. The premise of this article is that discrete categories do not exist in real life, and that it is misleading to refer to overlapping categories or symptoms as "comorbidities." We illustrate our point by presenting data from 179 school-age children evaluated with rigorous research criteria for seven disorders: reading disability (RD), attention-deficit/hyperactivity disorder (ADHD), developmental coordination disorder (DCD), oppositional defiant disorder (ODD), conduct disorder (CD), depression, and anxiety. Fully 50% of this sample met the criteria for at least two diagnoses. The children with ADHD were at higher risk of having at least a second disorder compared to the children with RD. Overall, the high rates of overlap of these behavioral, emotional, and educational deficits in this broadly ascertained sample support the idea that the concept of comorbidity is inadequate. We discuss the concept of atypical brain development as an explanatory idea to interpret the high rate of overlap of developmental disorders.

Learning disabilities and executive dysfunction in boys with attention-deficit/hyperactivity disorder

The effect of comorbid reading or arithmetic learning disabilities (LDs) on neuropsychological function in attention-deficit/hyperactivity disorder (ADHD) was studied. Participants were young males diagnosed with ADHD, with and without LD, and non-ADHD, non-LD male controls of similar age. LD was defined by combined regression-based and low-achievement classifications. Analyses adjusted for the effect of psychiatric comorbidity, age, and socioeconomic status on neuropsychological function. Children who had both ADHD and LD were significantly more impaired on both executive and nonexecutive functions than ADHD children without LD. Neuropsychological performance was most impaired in ADHD with combined arithmetic and reading disability. These data indicate that comorbid LD, especially arithmetic disability, significantly increases the severity of executive function impairment in ADHD.

Naming and verbal memory skills in adults with Attention Deficit Hyperactivity Disorder and Reading Disability

Research suggests that children with Attention Deficit Hyperactivity Disorder (ADHD) and Reading Disability (RD) can be differentiated based on their performance on measures of naming and verbal memory. It is not known whether this same pattern characterizes adults with these disorders. In this study, adults with and without ADHD and RD were compared on naming and verbal memory abilities. Results did not support the hypothesis that adults with ADHD and RD are significantly different from each other, or from a contrast group, on naming and verbal memory measures after controlling for Full-Scale IQ (FSIQ). These results were replicated across two sets of classification criteria used to identify diagnostic groups. Factors that could account for the inconsistency in research findings with children and adult subjects are discussed.

Cerebellar tests differentiate between groups of poor readers with and without IQ discrepancy

A comprehensive test battery, including phonological, speed, motor and cerebellar tasks, was administered to the entire cohort of two schools for children with learning disabilities. Testing was undertaken blind without accessing the psychometric data on the children. Children were then allocated to a discrepancy group on the basis of their IQ, with the majority (n = 29) classified as nondiscrepant (IQ < 90) and a smaller set (n = 7), with IQ of at least 90, classified as discrepant (with dyslexia). Both groups showed significant deficits relative to age-matched controls on almost all the tests. On phonological, speed, and motor tasks, the nondiscrepant group were at least as severely impaired as the discrepant group. By contrast, on the cerebellar tests of postural stability and muscle tone, the nondiscrepant group performed significantly better than the children with dyslexia and close to the level of the controls. The findings indicate that cerebellar tests may prove a valuable method of differentiating between poor readers with and without IQ discrepancy. The findings are interpreted in terms of the cerebellar deficit hypothesis for dyslexia.

Boys with reading disabilities and/or ADHD: distinctions in early childhood

We examined distinctions in the early childhood characteristics of boys with reading disabilities (RD) and/or attention-deficit/ hyperactivity disorder (ADHD). A four-group mixed design consisting of boys identified at age 11 with reading disabilities only (RD only; n = 46), reading disabilities and ADHD (RD/ADHD; n = 16), ADHD only (n = 20), and a comparison group (n = 281) was utilized. Differences on receptive and expressive language and temperament for ages 3 and 5 were investigated. Analyses indicated that the boys from the RD-only group performed worse on measures of receptive and expressive language. The results also indicated that boys from the RD/ADHD groups consistently performed worse on measures of receptive language and exhibited more behaviors indicative of an undercontrolled temperament. In summary, we suggest that reading disabilities and ADHD represent moderately unique disorders that frequently co-occur and are characterized by distinct developmental pathways.

Learning disabilities and ADHD: overlapping spectrumn disorders

Clinical and psychoeducational data were analyzed for 119 children ages 8 to 16 years who were evaluated in a child diagnostic clinic. A learning disability (LD) was present in 70% of the children with attention-deficit/hyperactivity disorder (ADHD), with a learning disability in written expression two times more common (65%) than a learning disability in reading, math, or spelling. Children with LD and ADHD had more severe learning problems than children who had LD but no ADHD, and the former also had more severe attention problems than children who had ADHD but no LD. Further, children with ADHD but no LD had some degree of learning problem, and children with LD but no ADHD had some degree of attention problem. Results suggest that learning and attention problems are on a continuum, are interrelated, and usually coexist.

How children with neurofibromatosis type 1 differ from "typical" learning disabled clinic attenders: nonverbal learning disabilities revisited

To further investigate cognitive deficits in children with Neurofibromatosis Type 1 (NF-1), children with NF-1 were compared to typical learning disabled clinic attenders (LD-clinic), all of whom had reading disabilities, as well as to a group with no disabilities (NoDx). Results indicated that both the NF-1 group and LD-clinic group had reading and reading-related deficits when compared to the NoDx group; however, the NF-1 group was more globally language impaired than the LD-clinic group. In addition, the NF-1 group scored significantly lower than the LD-clinic group, but not the NoDx group, on the visuospatial measures, thus confirming that children with NF-1 have visuospatial deficits not typical of a general LD-clinic population. The NF-1 group was not impaired in comparison to the NoDx group on certain language and visuospatial tasks that were previously found to be deficits in sibling pairwise matched designs; thus, the importance of considering genetic and familial context when studying the impact of genetic disorders on cognition was demonstrated.

Phonological processing, not inhibitory control, differentiates ADHD and reading disability

OBJECTIVE

To test for the distinctiveness of attention-deficit hyperactivity disorder (ADHD) and reading disability (RD) and the independence of the cognitive domains, inhibition and phonological processing, which are proposed as central to ADHD and RD, respectively, using a classic double dissociation design.

METHOD

A 2 (ADHD versus no ADHD) x 2 (RD versus no RD) model was used to examine the cognitive profile of 4 groups of children, aged 7 to 11 years. Two measures of inhibitory control and 3 phonological processing measures were used.

RESULTS

The 2 RD groups (RD, ADHD + RD) were significantly impaired relative to the 2 non-RD groups (controls, ADHD) on all phonological processing measures. The 2 ADHD groups were significantly impaired on simple go-task responding relative to the non-ADHD groups and in inhibition. Contrary to predictions, an RD effect on inhibitory control was found on one inhibition measure. The comorbid group (ADHD + RD) generally exhibited the deficits of both single groups in an additive fashion.

CONCLUSIONS

These findings question the role of inhibitory control as a unique cognitive marker for ADHD and suggest true comorbidity for children with both ADHD and RD.

Comorbidity of learning and attention disorders. Separate but equal

Children with learning and attention disorders commonly present with symptoms of both types of disorders. In many children, this co-occurrence represents comorbid disorders that are separate but overlapping. Because of comorbidity, the presence of one disorder signals the need to evaluate for the other disorders. Evaluation and treatment approaches must address both disorders when present.

Executive functioning deficits in attention-deficit/hyperactivity disorder are independent of oppositional defiant or reading disorder

OBJECTIVE

To evaluate deficits of executive functions in children with attention-deficit/hyperactivity disorder (ADHD) classified by type (combined [CT] or predominantly inattentive [IT]) and comorbidity with oppositional defiant disorder (ODD) and reading disorder (RD).

METHOD

The Wisconsin Card Sorting Test (WCST) and Tower of Hanoi (TOH) were administered to 28 community volunteers and 359 children (7.5-13.5 years old) divided into ADHD types, RD, and ODD.

RESULTS

ADHD/CT children solved fewer puzzles and violated more rules on the TOH than ADHD/IT or non-ADHD subjects. On the WCST there were no differences between diagnostic samples in perseverativeness, but ADHD/CT patients made more nonperseverative errors than ADHD/IT children. ODD was associated with moderately better TOH performance and RD with excessive rule breaks.

CONCLUSIONS

Executive functioning deficits were found for only ADHD/CT children and were independent of comorbidity with RD or ODD.

Ist Leseschwäche durch ein Automatisierungsdefizit verursacht?

Zusammenfassung: Die vorliegende Studie überprüft die Hypothese von Nicolson und Fawcett (1990) , daß leseschwache Kinder an einem allgemeinen Automatisierungsdefizit leiden und nicht - wie die gängige Lehrmeinung (z. B. Shaywitz, 1997 ) annimmt - an einer spezifisch phonologischen Schwäche. 24 leseschwache Kinder (neun- und zehnjährige) wurden mit 24 normallesenden Kindern beim Balancieren auf jeweils einem Bein verglichen, wobei drei Aufgabenstellungen realisiert wurden: Balancieren ohne Zusatzaufgabe, Balancieren mit verbundenen Augen und Balancieren mit Zusatzaufgabe. Leseschwache Kinder zeigten schlechtere Balancierleistungen vor allem beim Balancieren mit verbundenen Augen. Allerdings war dieses Defizit nicht mehr reliabel, wenn Unterschiede zwischen den leseschwachen und den normallesenden Kindern in bezug auf Unaufmerksamkeit und Überaktivität kontrolliert wurden. Es liegt die Vermutung nahe, daß die ursprünglichen Befunde zum Balancierdefizit leseschwacher Kinder dadurch zustandekamen, daß sich unter den untersuchten leseschwachen Kindern eine Anzahl von Teilnehmern mit zusätzlicher Beeinträchtigung der Aufmerksamkeit und der Aktivitätsregulation befanden.

The overlap of attention deficit hyperactivity disorder with other common mental disorders

OBJECTIVE

The literature on the overlap (co-morbidity) of attention deficit hyperactivity disorder (ADHD) with conduct disorder, specific learning disability, and anxiety disorders was reviewed to examine: (i) the evidence for ADHD being a syndrome distinct from the other conditions; and (ii) the evidence for co-morbid patterns representing meaningful subtypes of ADHD.

METHODOLOGY

Narrative review of the literature.

CONCLUSIONS

Conduct disorder is distinguished from ADHD by prognosis, patterns of association and familial aggregation. Pure' disorders are uncommon, however, and there is little evidence to support a distinct co-morbid subtype. There are few data that reliably distinguish ADHD from specific learning disabilities, but there are weaknesses in research to date. A specific ADHD+learning disabled subtype may exist, but as yet the implications for treatment are not known. Attention deficit hyperactivity disorder is distinguished from anxiety by symptom discrimination, factor analysis, patterns of association, familial aggregation and treatment response. There is evidence for a distinct ADHD+anxiety subtype.