ADHD and reading disabilities: a cluster analytic approach for distinguishing subgroups

Impact of Motivation on Selected Aspects of Attention in Children with ADHD

Earlier reports showed the co-occurrence of a motivation deficit in children with ADHD. The purpose of this study was to assess the impact of extrinsic motivation on selected aspects of attention in children with ADHD, as well as to measure cortical activity and dimensions of motivation as per the self-determination theory. The study included 30 children with ADHD and 30 typically developing (TD) children aged 9-13 years. Children with ADHD exhibited a higher theta/beta power ratio (TBR) in the midline and a lower regional cerebral blood oxygenation (rCBO₂) level in prefrontal areas measured using the HEG ratio compared to TD children. Children with ADHD were more likely to undertake activity under the pressure of external stimuli and exhibited attention deficits regarding vigilance, visual search and divided attention. Differences between groups regarding attention decreased in conditions of increased motivation, indicating that motivation can reduce cognitive deficits in children with ADHD.

Math Error Types and Correlates in Adolescents with and without Attention Deficit Hyperactivity Disorder

Objective: The aim of this study was to examine the types of errors made by youth with and without a parent-reported diagnosis of attention deficit and hyperactivity disorder (ADHD) on a math fluency task and investigate the association between error types and youths’ performance on measures of processing speed and working memory.

Method: Participants included 30 adolescents with ADHD and 39 typically developing peers between 14 and 17 years old matched in age and IQ. All youth completed standardized measures of math calculation and fluency as well as two tests of working memory and processing speed. Math fluency error patterns were examined.

Results: Adolescents with ADHD showed less proficient math fluency despite having similar math calculation scores as their peers. Group differences were also observed in error types with youth with ADHD making more switch errors than their peers.

Conclusion: This research has important clinical applications for the assessment and intervention on math ability in students with ADHD.

Novel subgroups of attention-deficit/hyperactivity disorder identified by topological data analysis and their functional network modular organizations

Attention-deficit/hyperactivity disorder (ADHD) is a clinically heterogeneous condition and identification of clinically meaningful subgroups would open up a new window for personalized medicine. Thus, we aimed to identify new clinical phenotypes in children and adolescents with ADHD and to investigate whether neuroimaging findings validate the identified phenotypes. Neuroimaging and clinical data from 67 children with ADHD and 62 typically developing controls (TDCs) from the ADHD-200 database were selected. Clinical measures of ADHD symptoms and intelligence quotient (IQ) were used as input features into a topological data analysis (TDA) to identify ADHD subgroups within our sample. As external validators, graph theoretical measures obtained from the functional connectome were compared to address the biological meaningfulness of the identified subtypes. The TDA identified two unique subgroups of ADHD, labelled as mild symptom ADHD (mADHD) and severe symptom ADHD (sADHD). The output topology shape was repeatedly observed in the independent validation dataset. The graph theoretical analysis showed a decrease in the degree centrality and PageRank in the bilateral posterior cingulate cortex in the sADHD group compared with the TDC group. The mADHD group showed similar patterns of intra- and inter-module connectivity to the sADHD group. Relative to the TDC group, the inter-module connectivity between the default mode network and executive control network were significantly increased in the sADHD group but not in the mADHD group. Taken together, our results show that the data-driven TDA is potentially useful in identifying objective and biologically relevant disease phenotypes in children and adolescents with ADHD.

A systematic review of attention deficit hyperactivity disorder (ADHD) and mathematical ability: current findings and future implications

BACKGROUND

Several recent behavioural and behavioural genetic studies have investigated the relationship between attention deficit hyperactivity disorder (ADHD) and mathematical ability. The aim of this systematic review was to provide an overview of these studies to date. An emphasis was placed on reviewing results that explored the association between mathematics and the two ADHD components of attention and hyperactivity-impulsivity separately.

METHODS

A systematic search of quantitative studies investigating the association between mathematics and ADHD was conducted across five databases (PsychINFO, Web of Science, PubMed, EMBASE, and Scopus). A total of 30 cross-sectional and four longitudinal studies were included in this review.

RESULTS

Narrative synthesis of the results was provided using PRISMA guidelines. Taken together, the studies pointed at substantial evidence for a negative association between ADHD symptoms and mathematical ability. This association was particularly marked for the inattentive component of ADHD than for the hyperactive-impulsive component. Evidence from twin studies also showed a significant genetic correlation between mathematics and ADHD, which was greater for the inattentive component of ADHD compared to the hyperactive-impulsive component.

CONCLUSIONS

The differential relationship of the hyperactivity-impulsivity and inattention domains with mathematics emphasises the heterogeneity within the disorder and suggests a partially different aetiology of the two ADHD domains. A better understanding of the aetiology of ADHD could help develop more efficient interventions aimed at the reduction of its symptoms. It could also offer an explanatory framework for shortcomings in achievement and inform the development of non-pharmacological intervention strategies.

ADHD symptomatology is best conceptualized as a spectrum: a dimensional versus unitary approach to diagnosis

The aim of this paper is to build a case for the utility of conceptualizing ADHD, not as a unitary disorder that contains several subtypes, but rather as a marker of impairment in attention and/or impulsivity that can be used to identify one of several disorders belonging to a spectrum. The literature will be reviewed to provide an overview of what is known about ADHD in terms of heterogeneity in symptomatology, neuropsychology, neurobiology, as well as comorbidity with other diseases and treatment options. The data from these areas of research will be critically analyzed to support the construct of a spectrum of disorders that can capture the great variability that exists between individuals with ADHD and can discriminate between separate disorders that manifest similar symptoms. The symptoms associated with ADHD can be viewed as dimensional markers that point to a spectrum of related disorders that have as part of their characteristics impairments of attention and impulsivity. The spectrum can accommodate symmetrically and asymmetrically comorbid psychiatric disorders associated with ADHD as well as the wide heterogeneity known to be a part of the ADHD disorder. Individuals presenting with impairments associated with ADHD should be treated as having a positive marker for a spectrum disorder that has as part of its characteristics impairments of attention and/or impulsivity. The identification of impairment in attention and/or impulsivity should be a starting point for further testing rather than being an endpoint of diagnosis that results in pharmacological treatment that may or may not be the optimal therapy. Rather than continuing to attribute a large amount of heterogeneity in symptom presentation as well as a high degree of symmetric and asymmetric comorbidity to a single disorder, clinical evaluation should turn to the diagnosis of the type of attentional deficit and/or impulsivity an individual has in order to colocate the individual's disorder on a spectrum that captures the heterogeneity in symptomatology, the symmetrical and asymmetrical comorbidity, as well as subthreshold presentation and other variants often worked into the disorder of ADHD. The spectrum model can accommodate not only the psychophysiological profiles of patients, but is also consistent with what is known about the functional heterogeneity of the prefrontal cortex as well as the construct that cognitive processes are supported by overlapping and collaborative networks.

WISC-IV profiles are associated with differences in symptomatology and outcome in children with ADHD

OBJECTIVE

The current study investigated the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) cluster profiles of children with ADHD to examine the association between IQ profiles and diagnostic frequency, symptomatology, and outcome in this population.

METHOD

Hierarchical cluster analysis was conducted on 189 children with a diagnosis of ADHD-inattentive (ADHD-I) and ADHD-combined (ADHD-C) subtypes. Clusters were then compared across symptom rating scale factor scores, behavioral rating scales, and achievement scores.

RESULTS

A five-cluster solution was extracted. One cluster was identified to have reduced processing speed relative to other WISC-IV indexes and significantly higher ratings of inattention and incidence of ADHD-I diagnosis. A second cluster had impairments in processing speed and working memory and was associated with impaired behavioral functioning.

CONCLUSION

Findings support a relationship between reduced processing speed and inattention and provide evidence that WISC-IV profiles may be helpful in predicting symptomatology and outcome in children with ADHD.

Functional disruption of the brain mechanism for reading: effects of comorbidity and task difficulty among children with developmental learning problems

OBJECTIVE

The study investigated the relative degree and timing of cortical activation associated with phonological decoding in poor readers.

METHOD

Regional brain activity was assessed during performance of a pseudoword reading task and a less demanding, letter-sound naming task by three groups of students: children who experienced reading difficulties without attention problems (N = 50, RD) and nonreading impaired (NI) readers either with (N = 20) or without attention-deficit/hyperactivity disorder (ADHD; N = 50). Recordings were obtained with a whole-head neuromagnetometer, and activation profiles were computed through a minimum norm algorithm.

RESULTS

Children with RD showed decreased amplitude of neurophysiological activity in the superior temporal gyrus, bilaterally, and in the left supramarginal and angular gyri during late stages of decoding, compared to typical readers. These effects were restricted to the more demanding pseudoword reading task. No differences were found in degree of activity between NI and ADHD students. Regression analyses provided further support for the crucial role of left hemisphere temporoparietal cortices and the fusiform gyrus for basic reading skills.

CONCLUSIONS

Results were in agreement with fMRI findings and replicate previous MEG findings with a larger sample, a higher density neuromagnetometer, an overt pseudoword reading task, and a distributed current source-modeling method.

Phenotypes within sensory modulation dysfunction

Sensory modulation disorder (SMD) is a severe inability to regulate responses to everyday sensory stimulation to which most people easily adapt. It is estimated to affect 5% to 16% of the general population of children. Although heterogeneity is seen in the presentation clinically, previous research has not empirically investigated whether the clinical heterogeneity of SMD can be classified into subtypes. This study explores a cohort of 98 children identified with SMD at the Department of Pediatric Rehabilitation by a member of the occupational therapy team at The Children's Hospital of Denver. Two subtypes of SMD were identified through cluster analysis based on data from 4 parent-report instruments. The first subtype is characterized by sensory seeking/craving, hyperactive, impulsive, externalizing (eg, delinquent, aggressive), unsocial, inadaptive, and impaired cognitive/social behavior. The second subtype is characterized by movement sensitivity, emotionally withdrawal, and low energy/weak behavior. Findings from this study present a step toward understanding and classifying the complexities of children with SMDs.

Evaluating reading and metacognitive deficits in children and adolescents with attention deficit hyperactivity disorder

The reading achievement of children and adolescents with Attention Deficit Hyperactivity Disorder (ADHD) has scarcely been explored in research conducted in the Spanish language and when it has, the results have been contradictory. The focus of the present research is to analyze participants' reading competency and metacognitive strategies as they carry out reading comprehension tasks. The sample was comprised of 187 Argentine schoolchildren aged 9 to 13 years old. 94 constituted the control group and the clinical group consisted of 93 schoolchildren diagnosed with ADHD. The metacognitive assessment was made up of two metacognitive tests, the Reading Awareness Scale (ESCOLA; acronym in Spanish) and a Spanish adaptation of Metacognitive Awareness of Reading Strategies Inventory (MARSI), and one test of reading comprehension, the Evaluation of Reading Processes for Secondary Education Students (PROLEC-SE; acronym in Spanish). Students with ADHD had lower achievement on tests o reading comprehension compared to the control group. Nevertheless, our results suggest their difficulties did not stem from readin comprehension problems, but rather from alterations in their Executive Functions, because when subjects' reading comprehensio was equalized, students with ADHD still exhibited a lower level of Metacognition, particularly when it came to planning.

Neuroscience: viable applications in education?

As a relatively young science, neuroscience is still finding its feet in potential collaborations with other disciplines. One such discipline is education, with the field of neuroeducation being on the horizon since the 1960s. However, although its achievements are now growing, the partnership has not been as successful as first hopes suggested it should be. Here the authors discuss the theoretical barriers and potential solutions to this, which have been suggested previously, with particular focus on levels of research in neuroscience and their applicability to education. Moreover, they propose that these theoretical barriers are driven and maintained by practical barriers surrounding common language and research literacy. They propose that by overcoming these practical barriers through appropriate training and shared experience, neuroeducation can reach its full potential.

Executive function in adolescence among children with attention-deficit/hyperactivity disorder in Taiwan

OBJECTIVE

Little is known about executive function among adolescents with a childhood diagnosis of attention-deficit/hyperactivity disorder (ADHD), and there is a lack of such information in an ethnic Chinese population. This study investigated nonverbal executive functions in adolescence among Taiwanese children with ADHD.

METHODS

The sample included fifty-three 11- to 16-year-old adolescents (male, 75.5%) with a childhood diagnosis of ADHD according to the DSM-IV criteria, and 53 age-, sex-, IQ-, and parental education-matched comparison adolescents. They were assessed using psychiatric interviews (mothers included), the Weschler Intelligence Scale for Children-3rd edition, and the tasks involving the executive functions of the Cambridge neuropsychological test automated battery: the spatial span, spatial working memory, intradimensional/extradimensional shifts, and stocking of Cambridge. A linear multilevel model was used for data analysis for the matched case-control study design and repeated measures within the same participants.

RESULTS

Forty-three adolescents (81.1%) had persistent DSM-IV ADHD diagnosis. The ADHD group made more errors in the spatial span and spatial working memory, had more complete stage trials in the intradimensional/extradimensional shifts, and had fewer problems solved and shorter initial and subsequent thinking time in the stockings of Cambridge than the controls. The magnitudes of group differences increased with increased task difficulties. Persistent ADHD and methylphenidate did not make significant difference in executive functions.

CONCLUSIONS

The findings of the authors suggest that adolescents with childhood ADHD need extra assistance when they are assigned complex tasks regardless of persistence of ADHD at adolescence.

Improving expressive writing skills of children rated for ADHD symptoms

The present study examines the expressive writing abilities of children described by their teachers as having Attention Deficit Hyperactivity Disorder (ADHD) symptoms and of matched controls and the effects of two types of facilitation. A group of 35 ADHD children and matched controls are given the task of composing a letter either under standard instructions or with facilitation (a guide scheme), preceded by a brief training on how to use the facilitation. Results show that both groups drew benefit from the guide scheme. Despite the fact that differences between groups were maintained after the training for the case of spelling errors, the poorer performance of ADHD children vanished. It is concluded that ADHD children have poor expressive writing skills, but this can be improved through the help of a guide scheme preceded by brief training.

Neurobiology of attention deficit hyperactivity disorder

This article addresses the current understanding of the neurobiological bases of attention deficit hyperactivity disorder (ADHD), focusing on empiric research findings that connect genetic and environmental factors to structural and functional brain abnormalities, ultimately leading to a set of age-dependent behavioral manifestations. Section one presents evidence for genetic risk factors for ADHD and discusses the role of potential environmental factors in the etiology of the disorder. Section two focuses on brain imaging studies and how they have helped generate different hypotheses regarding the pathophysiology of ADHD. Finally, the article addresses the longitudinal course of symptoms in ADHD from infancy to adulthood in an attempt to place biological findings for this complex brain disorder in the context of maturation and development.

Expressive writing difficulties in children described as exhibiting ADHD symptoms

Three groups of children of different ages who were considered by their teachers as showing symptoms of attention-deficit/hyperactivity disorder (ADHD) and matched controls were tested in a series of expressive writing tasks, derived from a standardized writing test. In the first study, 24 sixth- and seventh-grade children with ADHD symptoms wrote a description of an image. The ADHD group's expressive writing was worse than that of the control group and associated with a higher number of errors, mainly concerning accents and geminates. The second study showed the generality of the effect by testing younger groups of children with ADHD symptoms and controls with another description task where a verbal description was substituted for the picture stimulus. The third study extended the previous observations with another type of writing task, the request of writing a narrative text. In all the three studies, children with ADHD symptoms scored lower than controls on four qualitative parameters (adequacy, structure, grammar, and lexicon), produced shorter texts, and made more errors. These studies show that children with ADHD symptoms have school difficulties also in writing-both in spelling and expression-and that these difficulties are extended to different tasks and ages.

ADHD and achievement: meta-analysis of the child, adolescent, and adult literatures and a concomitant study with college students

This article presents results from two interrelated studies. The first study conducted a meta-analysis of the published literature since 1990 to determine the magnitude of achievement problems associated with attention-deficit/hyperactivity disorder (ADHD). Effect sizes were significantly different between participants with and without ADHD (sample weighted r = .32, sample weighted d = . 71; p = .001). Effects were also examined according to the moderators of age, gender, achievement domain (reading, math, spelling), measurement method (standardized tests vs. grades, parent/teacher ratings, etc.), sample type (clinical vs. nonclinical), and system used to identify ADHD (DSM-III-R vs. DSM-IV). Significant differences emerged from the moderator comparisons. The second study, using averaged effect sizes from the first study as a baseline for comparison, investigated achievement levels for an understudied age group with ADHD, namely, college students. Unlike previous studies at the college level, the sample incorporated both student and parent ratings (N = 380 dyads). The results were comparable to outcomes from the meta-analysis for college students and adults. Analyses demonstrated modest (R = .21) but meaningful predictive validity across 1 year to end-of-first-year grades. However, unlike earlier studies with children and adolescents, student ratings were as predictive as parent ratings. Findings are discussed in terms of the impact of moderator variables on ADHD and achievement.

Attention deficit hyperactivity disorder with reading disabilities: preliminary genetic findings on the involvement of the ADRA2A gene

BACKGROUND

Attention deficit/hyperactivity disorder (ADHD) and reading disability (RD) tend to co-occur and quantitative genetic studies have shown this to arise primarily through shared genetic influences. However, molecular genetic studies have shown different genes to be associated with each of these conditions. Neurobiological studies have implicated noradrenergic function in the aetiology of ADHD that is comorbid with RD. This paper examines the neurobiological evidence and presents preliminary testing of the hypothesis that the ADRA2A receptor gene is contributing to ADHD and comorbid RD.

METHODS

One hundred and fifty-two children (140 boys, 12 girls) of British Caucasian origin, aged between 6 and 13 years and with a diagnosis of ADHD, were recruited. The children's reading ability was tested. Children were identified as having ADHD or ADHD plus RD (n=82). DNA was available for 110 parent child trios and 42 parent child duos. Genotyping was undertaken for an ADRA2A polymorphism.

RESULTS

For those with ADHD plus RD there was evidence of association with the alpha 2A adrenergic receptor (ADRA2A) polymorphism with the G allele being preferentially transmitted.

CONCLUSIONS

The preliminary evidence together with other neurobiological research findings suggests that the ADRA2A gene may contribute to comorbid ADHD and RD and needs to be properly examined.

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 stroop color-word interference test as an indicator of ADHD in poor readers

The performance on the Stroop Color-Word Interference Test of 36 boys with Attention Deficit Hyperactivity Disorder (ADHD) was compared with performances of a matched control sample. The control group outperformed their counterparts on the control and interference conditions of the Stroop test, suggesting ADHD-specific executive and reading deficits. When individuals with both ADHD and reading disorders were excluded from the analysis, the authors found a significant difference between the ADHD group and the control group on the color-word test, indicating that poor reading skills may produce false negatives on the Stroop test. However, fast and slow readers with ADHD did not perform differently from each other on the color-word test. The authors postulated the existence of two different causes of reading problems: phonological deficits and attentional deficits.

A cognitive tool to diagnose predominantly inattentive ADHD behavior

Poor performance on tests of reading comprehension could be the result of weak word-recognition skills, inconsistent attention (ADD), or a combination of the two. Identifying the source of the reading disability (RD) reliably has been difficult because inconsistent attention interferes with reading and weak word recognition skill makes attention wander. The situation is further complicated by the fact that there are no objective diagnostic tests for ADD (Breggin, 1998; Diller, 1998). We proposed a new model of differential diagnosis of ADHD-I/RD and field-tested its utility in two studies. The new diagnostic procedure utilizes intra-individual differences seen in the performance of at-risk learners on tasks related to reading that vary in the degree of sustained attention required for successful performance. The hypothesis is that children whose attention is inconsistent would perform more poorly on tests such as listening comprehension, which require sustained attention, than on tests such as reading comprehension, which are more tolerant of inattention. Such differences will not be seen in the test scores of children who have only a reading disability because their performance on reading tests is determined more by the difficulty level of the tests than by the sensitivity of the tests to attention. The validity of this new model was evaluated by determining the relationship between differences seen in the scores of tests that differ in their attention requirement and the degree of inconsistency in sustained attention as measured by Conners' CPT. The results of the two studies indicate this to be a viable approach. The results of the second study are presented in this report.

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.

Discrimination of DSM-IV and latent class attention-deficit/hyperactivity disorder subtypes by educational and cognitive performance in a population-based sample of child and adolescent twins

OBJECTIVE

Despite the general use of DSM-IV attention-deficit/hyperactivity disorder (ADHD) subtypes, there is controversy over the optimal phenotyping strategy for this disorder.This report contrasts two ADHD subtyping approaches on the prediction of cognitive function and educational achievement.

METHOD

ADHD subtypes were determined using DSM-IV and latent class approaches for a population sample of 1,154 child and adolescent twins using parent report data. Twins completed cognitive and achievement testing and parents reported on school grades, special education placement, and history of being held back in school.

RESULTS

The DSM-IV primarily inattentive and combined subtype ADHD groups showed significant deficits in cognitive and achievement testing, worse grades, and increased use of special education resources compared with the primarily hyperactive/impulsive subtype and no-ADHD groups. Clinically relevant and less severe latent class ADHD subtypes were also associated with deficits in cognitive and achievement testing, grades, and special education use.

CONCLUSIONS

DSM-IV primarily inattentive and combined subtypes of ADHD have similar significant patterns of cognitive and academic dysfunction in the general population. Latent class-defined ADHD subtypes also have patterns of serious cognitive and achievement deficits.