Background: This study tests a multiple cognitive deficit model of reading disability (RD), attention‐deficit/hyperactivity disorder (ADHD), and their comorbidity.
Methods: A structural equation ...model (SEM) of multiple cognitive risk factors and symptom outcome variables was constructed. The model included phonological awareness as a unique predictor of RD and response inhibition as a unique predictor of ADHD. Processing speed, naming speed, and verbal working memory were modeled as potential shared cognitive deficits.
Results: Model fit indices from the SEM indicated satisfactory fit. Closer inspection of the path weights revealed that processing speed was the only cognitive variable with significant unique relationships to RD and ADHD dimensions, particularly inattention. Moreover, the significant correlation between reading and inattention was reduced to non‐significance when processing speed was included in the model, suggesting that processing speed primarily accounted for the phenotypic correlation (or comorbidity) between reading and inattention.
Conclusions: This study illustrates the power of a multiple deficit approach to complex developmental disorders and psychopathologies, particularly for exploring comorbidities. The theoretical role of processing speed in the developmental pathways of RD and ADHD and directions for future research are discussed.
Background
Sluggish cognitive tempo (SCT) is distinct from attention‐deficit/hyperactivity disorder inattention (ADHD‐IN) and concurrently associated with a range of impairment domains. However, few ...longitudinal studies have examined SCT as a longitudinal predictor of adjustment. Studies to date have all used a relatively short longitudinal time span (6 months to 2 years) and only rating scale measures of adjustment. Using a prospective, multi‐method design, this study examined whether SCT and ADHD‐IN were differentially associated with functioning over a 10‐year period between preschool and the end of ninth grade.
Methods
Latent state‐trait modeling determined the trait variance (i.e. consistency across occasions) of SCT and ADHD‐IN across four measurement points (preschool and the end of kindergarten, first grade, and second grade) in a large population‐based longitudinal sample (N = 976). Regression analyses were used to examine trait SCT and ADHD‐IN factors in early childhood as predictors of functioning at the end of ninth grade (i.e. parent ratings of psychopathology and social/academic functioning, reading and mathematics academic achievement scores, processing speed and working memory).
Results
Both SCT and ADHD‐IN contained more trait variance (Ms = 65% and 61%, respectively) than occasion‐specific variance (Ms = 35% and 39%) in early childhood, with trait variance increasing as children progressed from preschool through early elementary school. In regression analyses: (a) SCT significantly predicted greater withdrawal and anxiety/depression whereas ADHD‐IN did not uniquely predict these internalizing domains; (b) ADHD‐IN uniquely predicted more externalizing behaviors whereas SCT uniquely predicted fewer externalizing behaviors; (c) SCT uniquely predicted shyness whereas both SCT and ADHD‐IN uniquely predicted global social difficulties; and (d) ADHD‐IN uniquely predicted poorer math achievement and slower processing speed whereas SCT more consistently predicted poorer reading achievement.
Conclusions
Findings of this study – from the longest prospective sample to date – provide the clearest evidence yet that SCT and ADHD‐IN often differ when it comes to the functional outcomes they predict.
Sluggish cognitive tempo (SCT) is marked by impairments across social, emotional, and academic functioning, but few studies have examined the association between SCT and neuropsychological ...functioning. The present study examined the associations between SCT and measures of processing speed, executive function, attention, and reaction time. From a larger sample of 8,238 children and adolescents, a subsample of 928 children were overselected for symptoms of SCT or attention-deficit/hyperactivity disorder (ADHD) and compared to a matched control sample of 652 individuals without elevations of ADHD or SCT (age range = 5.9-15.4 years). Multiple regression analyses revealed that symptoms of SCT were independently associated with deficits in nearly all domains assessed by a battery of neuropsychological assessments, including slower processing speed, poorer working memory, decreased inhibition, poorer vigilance, and increased reaction time. Further, weaknesses in all five of these domains remained significant even after symptoms of ADHD-inattention, anxiety, and depression were controlled. These findings add to literature that supports the validity of SCT as a symptom profile separate from ADHD-inattention symptoms.
Background
Although multiple cross‐sectional studies have shown symptoms of sluggish cognitive tempo (SCT) and attention‐deficit/hyperactivity disorder (ADHD) to be statistically distinct, studies ...have yet to examine the temporal stability and measurement invariance of SCT in a longitudinal sample. To date, only six studies have assessed SCT longitudinally, with the longest study examining SCT over a 2‐year period. The overall goals of this study were to assess the 10‐year longitudinal stability and interfactor relationships of ADHD and SCT symptoms among a community sample of children.
Methods
Confirmatory factor analysis was used to assess the temporal invariance of ADHD and SCT symptoms in a large population‐based longitudinal sample (International Longitudinal Twin Study of Early Reading Development) that included children assessed at preschool and after kindergarten, first, second, fourth, and ninth grades (n = 489). Latent autoregressive models were then estimated to assess the stability of these constructs.
Results
Results demonstrated invariance of item loadings and intercepts from preschool through ninth grades, as well as invariance of interfactor correlations. Results further indicated that both ADHD and SCT are highly stable across these years of development, that these symptom dimensions are related but also separable, and that hyperactivity/impulsivity and SCT are both more strongly correlated with inattention than with each other and show differential developmental trajectories. Specifically, even in the presence of latent simplex analyses providing support for the developmental stability of these dimensions, linear comparisons indicated that that mean levels of hyperactivity/impulsivity decreased with time, inattentive ratings were generally stable, and SCT tended to increase slightly across development.
Conclusions
This study adds to the current literature by being the first to systematically assess and demonstrate the temporal invariance and stability of ADHD and SCT across a span of 10 years.
Although behavioral difficulties are well documented in reading disabilities, little is known about the relationship between math ability and internalizing and externalizing behaviors. Here, we use ...standardized measures to investigate the relation among early math ability, math anxiety, and internalizing and externalizing behaviors in a group of 366 second and third graders. Math achievement was significantly correlated with attentional difficulties and social problems but not with internalizing symptoms. The relation between math achievement and externalizing behavioral problems was stronger in girls than in boys. Math achievement was not correlated with trait anxiety but was negatively correlated with math anxiety. Critically, math anxiety differed significantly between children classified as math learning disabled (MLD), low achieving (LA), and typically developing (TD), with math anxiety significantly higher in the MLD and LA groups compared to the TD group. Our findings suggest that, even in nonclinical samples, math difficulties at the earliest stages of formal math learning are associated with attentional difficulties and domain-specific anxiety. These findings underscore the need for further examination of the shared cognitive, neural, and genetic influences underlying problem solving and nonverbal learning difficulties and accompanying internalizing and externalizing behaviors.
Reading disability (RD) and math disability (MD) frequently co-occur, but the etiology of this comorbidity is not well understood. Groups with RD only (N = 241), MD only (N = 183), and RD + MD (N = ...188) and a control group with neither disorder (N = 411) completed a battery of measures of internalizing and externalizing psychopathology, social and academic functioning, and 10 neuropsychological processes. Groups with RD only, MD only, and RD + MD were significantly impaired versus the control group on nearly all measures, and the group with RD + MD was more impaired than the groups with MD and RD alone on measures of internalizing psychopathology, academic functioning, and 7 of 10 neuropsychological constructs. Multiple regression analyses of the neuropsychological measures indicated that deficits in reading and math were associated with shared weaknesses in working memory, processing speed, and verbal comprehension. In contrast, reading difficulties were uniquely associated with weaknesses in phoneme awareness and naming speed, and math deficits were uniquely associated with weaknesses in set shifting. These results support multiple-deficit neuropsychological models of RD and MD and suggest that RD and MD are distinct but related disorders that co-occur because of shared neuropsychological weaknesses in working memory, processing speed, and verbal comprehension.
The current study tested a multiple-cognitive predictor model of word reading, math ability, and attention in a community-based sample of twins ages 8 to 16 years (N = 636). The objective was to ...identify cognitive predictors unique to each skill domain as well as cognitive predictors shared among skills that could help explain their overlap and thus help illuminate the basis for comorbidity of related disorders (reading disability, math disability, and attention deficit hyperactivity disorder). Results indicated that processing speed contributes to the overlap between reading and attention as well as math and attention, whereas verbal comprehension contributes to the overlap between reading and math. There was no evidence that executive functioning skills help account for covariation among these skill domains. Instead, specific executive functions differentially related to certain outcomes (i.e., working memory to math and inhibition to attention). We explored whether the model varied in younger versus older children and found only minor differences. Results are interpreted within the context of the multiple deficit framework for neurodevelopmental disorders.
Three subtypes of attention-deficit/hyperactivity disorder (ADHD) based on numbers of symptoms of inattention (I) and hyperactivity-impulsivity (HI) were defined in the Diagnostic and Statistical ...Manual of Mental Disorders (4th ed.) to reduce heterogeneity of the disorder, but the subtypes proved to be highly unstable over time. A continuous alternative to nominal subtyping is evaluated in a longitudinal study of 129 four- to six-year-old children with ADHD and 130 comparison children. Children who met criteria for all subtypes in Year 1 continued to exhibit greater functional impairment than comparison children during Years 2 to 9. Among children with ADHD in Year 1, I and HI symptoms differentially predicted teacher-rated need for treatment and reading and mathematics achievement scores over the next 8 years in controlled analyses. Consistent with other studies, these findings suggest that the use of diagnostic modifiers specifying the numbers of I and HI symptoms could reduce heterogeneity and facilitate clinical intervention, prognosis, and research.
Objective:
In the last decade, there has been an increase in research that aims to parse heterogeneity in attention deficit hyperactivity disorder (ADHD). The current study tests heritability of ...latent class neuropsychological subtypes.
Method:
Latent class analysis was used to derive subtypes in a sample of school-age twins (N = 2,564) enriched for elevated ADHD symptoms.
Results:
Five neuropsychological profiles replicated across twin 1 and twin 2 datasets. Latent class membership was heritable overall, but heritability varied by profile and was lower than heritability of ADHD status. Variability in neuropsychological performance across domains was the strongest predictor of elevated ADHD symptoms. Neuropsychological profiles showed distinct associations with age, psychiatric symptoms and reading ability.
Conclusion:
Neuropsychological profiles are associated with unique neurocognitive presentations, but are not strong candidate endophenotypes for ADHD diagnosis.
Early reading skills are critical for later academic outcomes, which include mathematics. Yet, these relations may vary by a child’s ability level. This study examined how early reading skills relate ...to different levels of third-grade mathematics. The samples included 105 same-sex twin pairs (210 individuals, 57% female, 43% male) from the ongoing longitudinal Western Reserve Reading and Math Projects, assessed at kindergarten ( M = 6.18, SD = 0.44) and third grade ( M = 9.07, SD = 0.49). Kindergarten reading measures consisted of the Letter Identification task from the Woodcock Reading Mastery Test-Revised Normative Update, the Deletion subtests from Phonological Awareness Test, and the Letter Naming Fluency task from the Dynamic Indicators of Basic Early Literacy Skills; third-grade math measures included Calculation, Fluency, Applied Problem, and Quantitative Concepts subtests of Woodcock-Johnson III Tests of Achievement. Both linear and quantile regressions were conducted using reading measures as predictors and math measures as the dependent variables. Linear regressions indicated that the Deletion Summary Score was a unique predictor of Applied Problems, and Letter Naming Fluency was a significant and unique predictor of Calculation Fluency and Quantitative Concepts. Quantile regressions provided a more thorough analysis of these relations. It was found that Letter Naming Fluency was significantly associated with Calculation, Calculation Fluency, and Quantitative Concepts at the lower level. The Deletion Summary Score had relatively stable relations with Applied Problems across all levels. (PsycInfo Database Record (c) 2024 APA, all rights reserved) (Source: journal abstract)
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