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Background Males are diagnosed with dyslexia more frequently than females, even in epidemiological samples. This may be explained by greater variance in males' reading performance. Methods We expand on previous research by rigorously testing the variance difference theory, and testing for mediation of the sex difference by cognitive correlates. We developed an analytic framework that can be applied to group differences in any psychiatric disorder. Results Males' overrepresentation in the low performance tail of the reading distribution was accounted for by mean and variance differences across sex. There was no sex difference at the high performance tail. Processing speed ( PS) and inhibitory control partially mediated the sex difference. Verbal reasoning emerged as a strength in males. Conclusions Our results complement a previous finding that PS partially mediates the sex difference in symptoms of attention deficit/hyperactivity disorder ( ADHD), and helps explain the sex difference in both dyslexia and ADHD and their comorbidity. [ABSTRACT FROM AUTHOR]

Background The onset of hyperactivity/impulsivity and attention problems ( HAP) is typically younger than that of conduct problems ( CP), and some research supports a directional relation wherein HAP precedes CP. Studies have tested this theory using between-person and between-group comparisons, with conflicting results. In contrast, prior research has not examined the effects of within-person fluctuations in HAP on CP. Method This study tested the hypothesis that within-person variation in HAP would positively predict subsequent within-person variation in CP, in two population samples of youth ( N = 620) who participated in identical methods of assessment over the course of 30 months. Three-level, hierarchical models were used to test for within-person, longitudinal associations between HAP and CP, as well as moderating effects of between-person and between-family demographics. Results We found a small but significant association in the expected direction for older youth, but the opposite effect in younger and non-Caucasian youth. These results were replicated across both samples. Conclusions The process by which early HAP relates to later CP may vary by age and racial identity. [ABSTRACT FROM AUTHOR]

Background Males show higher rates of attention deficit hyperactivity disorder ( ADHD) than do females. Potential explanations include genuine etiological differences or artifact. Methods 2,332 twin and sibling youth participated in behavioral and cognitive testing. Partially competing models of symptom severity distribution differences, the mean difference, and variance difference models, were tested within a randomly selected subsample. The Delta method was used to test for mediation of sex differences in ADHD symptom severity by processing speed, inhibition and working memory. Results The combined mean difference and variance difference models fully explained the sex difference in ADHD symptom severity. Cognitive endophenotypes mediated 14% of the sex difference effect. Conclusions The sex difference in ADHD symptom severity is valid and may be due to differing genetic and cognitive liabilities between the sexes. [ABSTRACT FROM AUTHOR]

This study examined whether domain-general cognitive weaknesses in processing speed (PS) or executive functioning (EF) moderate the relation between word reading scores and anxiety such that lower word reading scores in combination with lower cognitive scores are associated with higher anxiety symptoms. The sample consisted of 755 youth ages 8–16 who were recruited as part of the Colorado Learning Disabilities Research Center twins study. Lower scores on PS (R 2 =.007, p =.014), EF (R 2 =.009, p =.006), and word reading (R 2 =.006–.008, p =.010–.032) were associated with higher anxiety scores. In addition, the word reading × cognitive interactions were significant such that lower scores on PS (R 2 =.010, p =.005) or EF (R 2 =.013, p =.010) combined with lower word reading were associated with higher-than-expected anxiety symptoms. Results suggest that weaknesses in PS, EF, and word reading are modestly associated with higher anxiety symptoms, and these anxiety symptoms may be compounded in youth with both PS or EF weaknesses and word reading difficulties. These findings can guide assessment approaches for identifying youth with word reading challenges who may be at increased risk for anxiety. [ABSTRACT FROM AUTHOR]

Limited evidence supports the external validity of the distinction between developmental phonological and surface dyslexia. We previously identified children ages 8 to 13 meeting criteria for these subtypes (Peterson, Pennington, & Olson, 2013) and now report on their reading and related skills approximately 5 years later. Longitudinal stability of subtype membership was fair and appeared stronger for phonological than surface dyslexia. Phonological dyslexia was associated with a pronounced phonological awareness deficit, but subgroups otherwise had similar cognitive profiles. Subtype did not inform prognosis. Results provide modest evidence for the validity of the distinction, although not for its clinical utility. [ABSTRACT FROM PUBLISHER]

Purpose: The goal of this study was to investigate the etiologic basis for the association between deficits in phonological memory (PM) and vocabulary in school-age children. Method: Children with deficits in PM or vocabulary were identified within the International Longitudinal Twin Study (ILTS; Samuelsson et al., 2005). The ILTS includes 1,045 twin pairs (between the ages of 5 and 8 years) from the United States, Australia, and Scandinavia. The authors applied the DeFries-Fulker (DeFries & Fulker, 1985, 1988) regression method to determine whether problems in PM and vocabulary tend to co-occur because of overlapping genes, overlapping environmental risk factors, or both. Results: Among children with isolated PM deficits, the authors found significant bivariate heritability of PM and vocabulary weaknesses both within and across time. However, when probands were selected for a vocabulary deficit, there was no evidence for bivariate heritability. In this case, it appears that the PM-vocabulary relationship is caused by common shared environmental experiences. Conclusions: The findings are consistent with previous research on the heritability of specific language impairment and suggest that there are etiologic subgroups of children with low vocabulary for different reasons, 1 being more influenced by genes and another being more influenced by environment. [ABSTRACT FROM AUTHOR]

Purpose: The goal of this study was to investigate the etiologic basis for the association between deficits in phonological memory (PM) and vocabulary in school-age children. Method: Children with deficits in PM or vocabulary were identified within the International Longitudinal Twin Study (ILTS; Samuelsson et al., 2005). The ILTS includes 1,045 twin pairs (between the ages of 5 and 8 years) from the United States, Australia, and Scandinavia. The authors applied the DeFries-Fulker (DeFries & Fulker, 1985, 1988) regression method to determine whether problems in PM and vocabulary tend to co-occur because of overlapping genes, overlapping environmental risk factors, or both. Results: Among children with isolated PM deficits, the authors found significant bivariate heritability of PM and vocabulary weaknesses both within and across time. However, when probands were selected for a vocabulary deficit, there was no evidence for bivariate heritability. In this case, it appears that the PM-vocabulary relationship is caused by common shared environmental experiences. Conclusions: The findings are consistent with previous research on the heritability of specific language impairment and suggest that there are etiologic subgroups of children with low vocabulary for different reasons, 1 being more influenced by genes and another being more influenced by environment. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the phonological and surface subtypes of developmental dyslexia in light of competing predictions made by two computational models of single word reading, the Dual-Route Cascaded Model (DRC; Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001) and Harm and Seidenberg’s connectionist model (HS model; Harm & Seidenberg, 1999). The regression-outlier procedure was applied to a large sample to identify children with disproportionately poor phonological coding skills (phonological dyslexia) or disproportionately poor orthographic coding skills (surface dyslexia). Consistent with the predictions of the HS model, children with “pure” phonological dyslexia, who did not have orthographic deficits, had milder phonological impairments than children with “relative” phonological dyslexia, who did have secondary orthographic deficits. In addition, pure cases of dyslexia were more common among older children. Consistent with the predictions of the DRC model, surface dyslexia was not well conceptualized as a reading delay; both phonological and surface dyslexia were associated with patterns of developmental deviance. In addition, some results were problematic for both models. We identified a small number of individuals with severe phonological dyslexia, relatively intact orthographic coding skills, and very poor real word reading. Further, a subset of controls could read normally despite impaired orthographic coding. The findings are discussed in terms of improvements to both models that might help better account for all cases of developmental dyslexia. [Copyright &y& Elsevier]

Although previous research has identified contemporaneous associations between cognitive deficits and symptom phenotypes in Attention Deficit/Hyperactivity Disorder, no studies have as yet attempted to identify direction of effect. The present study used cross-lagged path modeling to examine competing hypotheses about longitudinal associations between rapid naming speed and symptoms of inattention in children. 1,506 school-age twins from Australia and the U.S. were tested for inattention, hyperactivity/impulsivity, and rapid naming speed at three and four time points, respectively. Symptom severity of inattention from Kindergarten to fourth grade is consistently predicted by previous rapid naming, over and above auto-regressive and correlational associations in the model. Likewise, inattention symptoms have a small but significant predictive effect on subsequent rapid naming. The findings support a reciprocal relationship between naming speed and ADHD inattentive symptoms. [ABSTRACT FROM AUTHOR]

Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) criteria for attention deficit/hyperactivity disorder (ADHD) specify two dimensions of inattention and hyperactivity-i mpul-sivity symptoms that are used to define three nominal subtypes: predominantly hyperactive--impulsive type (ADHD-H), predominantly inattentive type (ADHD-I), and combined type (ADHD-C). To aid decision making for DSM-5 and other future diagnostic systems, a comprehensive literature review and meta-analysis of 546 studies was completed to evaluate the validity of the DSM-IV model of ADHD. Results indicated that DSM-IV criteria identify individuals with significant and persistent impairment in social, academic, occupational, and adaptive functioning when intelligence, demographic factors, and concurrent psychopathology are controlled. Available data overwhelmingly support the concurrent, predictive, and discriminant validity of the distinction between inattention and hyperactivity - impulsivity symptoms, and indicate that nearly all differences among the nominal subtypes are consistent with the relative levels of inattention and hyperactivity--impulsivity symptoms that define the subtypes. In contrast, the DSM-IV subtype model is compromised by weak evidence for the validity of ADHD-H after first grade, minimal support for the distinction between ADHD-I and ADHD-C in studies of etiological influences, academic and cognitive functioning, and treatment response, and the marked longitudinal instability of all three subtypes. Overall, we conclude that the DSM-IV ADHD subtypes provide a convenient clinical shorthand to describe the functional and behavioral correlates of current levels of inattention and hyperactivity--impulsivity symptoms, but do not identify discrete subgroups with sufficient long-term stability to justify the classification of distinct forms of the disorder. Empirical support is stronger for an alternative model that would replace the subtypes with dimensional modifiers that reflect the number of inattention and hyperactivity-impulsivity symptoms at the time of assessment. [ABSTRACT FROM AUTHOR]

The article discusses a seminar about dyslexia, a neurodevelopmental disorder that is characterized by slow and inaccurate word recognition. It confirms that dyslexia is characterized by dysfunction of the normal left hemisphere language network and also implicates abnormal white matter development. Studies accounting for reading experience demonstrate that many recorded neural differences show causes rather than effects of dyslexia.

Background: Reading disability (RD) and attention deficit/hyperactivity disorder (ADHD) are comorbid and genetically correlated, especially the inattentive dimension of ADHD (ADHD-I). However, previous research indicates that RD and ADHD enter into opposite gene by environment (G × E) interactions. Methods: This study used behavioral genetic methods to replicate these opposite G × E interactions in a sample of same-sex monozygotic and dizygotic twin pairs from the Colorado Learning Disabilities Research Center (CLDRC; ) and to test a genetic hypothesis for why these opposite interactions occur. Results: We replicated opposite G × E interactions for RD (bioecological) and ADHD-I (diathesis-stress) with parental education in the same sample of participants. The genetic hypothesis for this opposite pattern of interactions is that only genes specific to each disorder enter into these opposite interactions, not the shared genes underlying their comorbidity. To test this hypothesis, we used single models with an exploratory three-way interaction, in which the G × E interactions for each disorder were moderated by comorbidity. Neither three-way interaction was significant. The heritability of RD did not vary as a function of parental education and ADHD-I. Similarly, the heritability of ADHD-I did not vary as a function of parental education and RD. Conclusions: We documented opposite G × E interactions in RD and ADHD-I in the same overall twin sample, but the explanation for this apparent paradox remains unclear. Examining specific genes and more specific environmental factors may help resolve the paradox. [ABSTRACT FROM AUTHOR]

The overall goals of this study were to test single versus multiple cognitive deficit models of dyslexia (reading disability) at the level of individual cases and to determine the clinical utility of these models for prediction and diagnosis of dyslexia. To accomplish these goals, we tested five cognitive models of dyslexia—two single-deficit models, two multiple-deficit models, and one hybrid model—in two large population-based samples, one cross-sectional (Colorado Learning Disability Research Center) and one longitudinal (International longitudinal Twin Study). The cognitive deficits included in these cognitive models were in phonological awareness, language skill, and processing speed and/or naming speed. To determine whether an individual case fit one of these models, we used two methods: 1) the presence or absence of the predicted cognitive deficits, and 2) whether the individual's level of reading skill best fit the regression equation with the relevant cognitive predictors (i.e., whether their reading skill was proportional to those cognitive predictors.) We found that roughly equal proportions of cases met both tests of model fit for the multiple deficit models (30-36%) and single deficit models (24-28%); hence, the hybrid model provided the best overall fit to the data. The remaining roughly 40% of cases in each sample lacked the deficit or deficits that corresponded with their best-fitting regression model. We discuss the clinical implications of these results for both diagnosis of school-age children and preschool prediction of children at risk for dyslexia. [ABSTRACT FROM AUTHOR]

This study tests a multiple cognitive deficit model of reading disability (RD), attention-deficit/hyperactivity disorder (ADHD), and their comorbidity. 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. 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. 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. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: Children with speech sound disorder (SSD) and reading disability (RD) have poor phonological awareness, a problem believed to arise largely from deficits in processing the sensory information in speech, specifically individual acoustic cues. However, such cues are details of acoustic structure. Recent theories suggest that listeners also need to be able to integrate those details to perceive linguistically relevant form. This study examined abilities of children with SSD, RD, and SSD+RD not only to process acoustic cues but also to recover linguistically relevant form from the speech signal. Method: Ten- to 11-year-olds with SSD (n =17), RD (n =16), SSD+RD (n =17), and Controls (n =16) were tested to examine their sensitivity to (1) voice onset times (VOT); (2) spectral structure in fricative-vowel syllables; and (3) vocoded sentences. Results: Children in all groups performed similarly with VOT stimuli, but children with disorders showed delays on other tasks, although the specifics of their performance varied. Conclusion: Children with poor phonemic awareness not only lack sensitivity to acoustic details, but are also less able to recover linguistically relevant forms. This is contrary to one of the main current theories of the relation between spoken and written language development. Learning outcomes: Readers will be able to (1) understand the role speech perception plays in phonological awareness, (2) distinguish between segmental and global structure analysis of speech perception, (3) describe differences and similarities in speech perception among children with speech sound disorder and/or reading disability, and (4) recognize the importance of broadening clinical interventions to focus on recognizing structure at all levels of speech analysis. [Copyright &y& Elsevier]

Not long ago, poor language skills did not necessarily interfere with the quality of a person’s life. Many occupations did not require sophisticated language or literacy. Interactions with other people could reasonably be restricted to family members and a few social or business contacts. But in the 21st century, advances in technology and burgeoning population centers have made it necessary for children to acquire high levels of proficiency with at least one language, in both spoken and written form. This situation increases the urgency for us to develop better theoretical accounts of the problems underlying disorders of language, including dyslexia. Empirical investigations of language-learning deficits largely focus on phonological representations and often ask to what extent labeling responses are ‘‘categorical.’’ This article describes the history of this approach and presents some relevant findings regarding the perceptual organization of speech signals—findings that should prompt us to expand our investigations of language disorders. [ABSTRACT FROM PUBLISHER]

Background Efficient memory functions are important to the development of cognitive and functional skills, allowing individuals to manipulate and store information. Theories of memory have suggested the presence of domain-specific (i.e. verbal and spatial) and general processing mechanisms across memory domains, including memory functions dependent on the prefrontal cortex (PFC) and the hippocampus. Comparison of individuals who have syndromes associated with striking contrasts in skills on verbal and spatial tasks [e.g. Down syndrome (DS) and Williams syndrome (WS)] allows us to test whether or not these dissociations may extend across cognitive domains, including PFC and hippocampal memory processes. Methods The profile of memory function, including immediate memory (IM), working memory (WM) and associative memory (AM), was examined in a sample of adolescents and young adults with DS ( n = 27) or WS ( n = 28), from which closely CA- and IQ-matched samples of individuals with DS ( n = 18) or WS ( n = 18) were generated. Relations between memory functions and IQ and adaptive behaviour were also assessed in the larger sample. Results Comparisons of the two matched groups indicated significant differences in verbal IM (DS < WS), spatial IM (DS > WS) and spatial and verbal AM (DS > WS), but no between-syndrome differences in WM. For individuals with DS, verbal IM was the most related to variation in IQ, and spatial AM related to adaptive behaviour. The pattern was clearly different for individuals with WS. Verbal and spatial AM were the most related to variation in IQ, and verbal WM related to adaptive behaviour. Conclusions These results suggest that individuals with these two syndromes have very different patterns of relative strengths and weaknesses on memory measures, which do not fully mirror verbal and spatial dissociations. Furthermore, different patterns of memory dysfunction relate to outcome in individuals with each syndrome. [ABSTRACT FROM AUTHOR]

Purpose: In this study, the authors evaluated literacy outcome in children with histories of speech sound disorder (SSD) who were characterized along 2 dimensions: broader language function and persistence of SSD. In previous studies, authors have demonstrated that each dimension relates to literacy but have not disentangled their effects. Methods: Two groups of children (86 SSD and 37 controls) were recruited at ages 5-6 and were followed longitudinally. The authors report the literacy of children with SSD at ages 7-9, compared with controls and national norms, and relative to language skill and SSD persistence (both measured at age 5-6). Results: The SSD group demonstrated elevated rates of reading disability. Language skill but not SSD persistence predicted later literacy. However, SSD persistence was associated with phonological awareness impairments. Phonological awareness alone predicted literacy outcome less well than a model that also included syntax and nonverbal IQ. Conclusions: Results support previous literature findings that SSD history predicts literacy difficulties and that the association is strongest for SSD + language impairment (LI).Magnitude of phonological impairment alone did not determine literacy outcome, as predicted by the core phonological deficit hypothesis. Instead, consistent with a multiple deficit approach, phonological deficits appeared to interact with other cognitive factors in literacy development. [ABSTRACT FROM AUTHOR]

Background: Deficient rapid auditory processing (RAP) has been associated with early language impairment and dyslexia. Using an auditory masking paradigm, children with language disabilities perform selectively worse than controls at detecting a tone in a backward masking (BM) condition (tone followed by white noise) compared to a forward masking (FM) condition (tone preceded by white noise). Tallal’s (1980) auditory processing hypothesis posits that abnormal RAP leads to reduced (or impaired) phonological awareness (PA), resulting in reading and language difficulties. Alternative theories suggest that impaired PA may have more of a top-down effect on auditory processing. Methods: The current study examines RAP in children tested at two time points, average age 5.6 and average age 8.3, in order to test causal relations between RAP and PA in a path analysis. Additional hierarchical regressions examine how well RAP predicts reading ability when accounting for PA and vocabulary. Results: The path analysis indicates a top-down effect, such that PA has a larger impact on BM over time than the reverse. Regressions indicate no direct impact of RAP on reading ability. Discussion: The path analysis provides evidence against the auditory processing hypothesis and instead suggests that between the ages of 5 and 8 it is variability in early phonological representations that predicts subsequent lower-level rapid auditory processing. [ABSTRACT FROM AUTHOR]

In this article, we critically review the evidence for overlap among three developmental disorders, namely speech sound disorder (SSD), language impairment (Li), and reading disability (RD), at three levels of analysis: diagnostic, cognitive, and etiological. We find that while overlap exists at all three levels, it varies by comorbidity subtype, and the relations among these three disorders are complex and not fully understood. We evaluate which comorbidity models can be rejected or supported as explanations for why and how these three disorders overlap and what new data are needed to better define their relations. [ABSTRACT FROM AUTHOR]

This review includes 1) an explanation of what neuropsychology is, 2) a brief history of how developmental cognitive neuroscience emerged from earlier neuropsychological approaches to understanding atypical development, 3) three recent examples that illustrate the benefits of this approach, 4) issues and challenges this approach must face, and 5) a forecast for the future of this approach. [ABSTRACT FROM AUTHOR]

This article examines Gene X Environment (G X E) interactions in two comorbid developmental disorders reading disability (RD) and attention-deficit/hyperactivity disorder (ADHD)-as a window on broader issues on G )< E interactions in developmental psychology. The authors first briefly review types of G X E interactions, methods for detecting them, and challenges researchers confront in interpreting such interactions. They then review previous evidence for G X E interactions in RD and ADHD, the directions of which are opposite to each other: bioecological for RD and diathesis stress for ADFLD. Given these results, the authors formulate and test predictions about G X E interactions that would be expected at the favorable end of each symptom dimension (e.g., above-average reading or attention). Consistent with their prediction, the authors found initial evidence for a resilience interaction for above-average reading: higher heritability in the presence of lower parental education. However, they did not find a G X E interaction at the favorable end of the ADHD symptom dimension. The authors conclude with implications for future research. [ABSTRACT FROM AUTHOR]

Abstract: Typical U.S. children use their knowledge of letters’ names to help learn the letters’ sounds. They perform better on letter sound tests with letters that have their sounds at the beginnings of their names, such as v, than with letters that have their sounds at the ends of their names, such as m, and letters that do not have their sounds in their names, such as h. We found this same pattern among children with speech sound disorders, children with language impairments as well as speech sound disorders, and children who later developed serious reading problems. Even children who scored at chance on rhyming and sound matching tasks performed better on the letter sound task with letters such as v than with letters such as m and h. Our results suggest that a wide range of children use the names of letters to help learn the sounds and that phonological awareness, as conventionally measured, is not required in order to do so. [Copyright &y& Elsevier]

Few studies have investigated the role of gene × environment interactions (G × E) in speech, language, and literacy disorders. Currently, there are two theoretical models, the diathesis–stress model and the bioecological model, that make opposite predictions about the expected direction of G × E, because environmental risk factors may either strengthen or weaken the effect of genes on phenotypes. The purpose of the current study was to test for G × E at two speech sound disorder and reading disability linkage peaks using a sib-pair linkage design and continuous measures of socioeconomic status, home language/literacy environment, and number of ear infections. The interactions were tested using composite speech, language, and preliteracy phenotypes and previously identified linkage peaks on 6p22 and 15q21. Results showed five G × E at both the 6p22 and 15q21 locations across several phenotypes and environmental measures. Four of the five interactions were consistent with the bioecological model of G × E. Each of these four interactions involved environmental measures of the home language/literacy environment. The only interaction that was consistent with the diathesis–stress model was one involving the number of ear infections as the environmental risk variable. The direction of these interactions and possible interpretations are explored in the discussion. [ABSTRACT FROM PUBLISHER]

Abstract: This commentary explains how the field of developmental cognitive neuroscience (DCN) holds the promise of a much wider interdisciplinary integration across sciences concerned with development: psychology, molecular genetics, neurobiology, and evolutionary developmental biology. First we present a brief history of DCN, including the key theoretical issues it addresses; then we comment on how the four articles in this special section exemplify a DCN approach and raise important theoretical and methodological issues for the field of DCN; and we close by considering the future of DCN, especially the key role developmental psychologists can play as DCN becomes increasingly interdisciplinary. [Copyright &y& Elsevier]

Visual perception may be a developmental prerequisite to some types of social understanding. The ability to perceive social information given visual motion appears to develop early. However, children with autism have profound deficits in social cognitive function and may fail to see social motion in the same way that typically developing children do. We tested the hypothesis that children with autism fail to discriminate animate motion, using a novel paradigm involving simple geometric figures. The subjects were 23 children with autism (c.a. 70.7 mos.), 18 children with other developmental disabilities (c.a. 68.2 mos.), and 18 typically developing children (c.a. 46.4 mos.). Children saw two circles moving on a screen and were rewarded for identifying the one that moved as if animate. A control condition required children to identify the heavier of two objects. Children with autism initially showed a deficit in categorizing objects as animate (though no deficit on the control task), but showed no deficit in this ability after they had reached criterion in the training phase. These results are discussed in terms of the social orienting theory of autism, and the possibility that animacy perception might be preserved in autism, even if it is not used automatically. [ABSTRACT FROM AUTHOR]

Abstract: This study tested the segmentation hypothesis of dyslexia by measuring implicit phonological representations in reading-disabled 11- to 13-year-olds. Implicit measures included lexical gating, priming, and syllable similarity tasks designed to reduce metalinguistic demands. Children with dyslexia performed consistently worse than CA and RA controls when more segmental representations were required across all three tasks. Implicit phonological representations were correlated with measures of speech perception, phoneme awareness, and phonological short-term memory, but not rapid automatized naming, and accounted for unique variance in predicting reading ability. Results provide strong support for less mature implicit phonological representations in children with dyslexia. [Copyright &y& Elsevier]

Abstract: The emerging etiological model for developmental disorders, like dyslexia, is probabilistic and multifactorial while the prevailing cognitive model has been deterministic and often focused on a single cognitive cause, such as a phonological deficit as the cause of dyslexia. So there is a potential contradiction in our explanatory frameworks for understanding developmental disorders. This paper attempts to resolve this contradiction by presenting a multiple cognitive deficit model of developmental disorders. It describes how this model evolved out of our attempts to understand two comorbidities, those between dyslexia and attention deficit hyperactivity disorder (ADHD) and between dyslexia and speech sound disorder (SSD). [Copyright &y& Elsevier]

The profile of spatial ability is of interest across autism spectrum disorders (ASD) because of reported spatial strengths in ASD and due to the recent association of Asperger’s syndrome with Nonverbal Learning Disability. Spatial functions were examined in relation to two cognitive theories in autism: the central coherence and executive function (EF) theories. Performance on spatial tasks, EFs, and global/local processing was compared in children with ASD and controls. While the ASD group had faster reaction times on the Embedded Figures task, spatial performance was intact, but not superior, on other tasks. There was no evidence for impairments in EF or in processing global/local information, therefore contradicting these two theories. The implications of these results for these two theories are discussed. [ABSTRACT FROM AUTHOR]

Background: Speech sound disorder (SSD) is a common childhood disorder characterized by developmentally inappropriate errors in speech production that greatly reduce intelligibility. SSD has been found to be associated with later reading disability (RD), and there is also evidence for both a cognitive and etiological overlap between the two disorders. The present study tested whether SSD is linked to replicated risk loci for RD. Method: One hundred and eleven probands with SSD and their 76 siblings were tested with measures of speech, phonological memory (Nonword Repetition -- NWR), and phonological awareness and genotyped for linkage markers on chromosomes 1p36, 6p22, and 15q21. Both single point and multipoint linkage were tested with multiple methods. Results: The speech and NWR phenotypes were linked to the RD loci on chromosomes 6 and 15, with suggestive results for the RD locus on chromosome 1. Conclusions: It now appears that several RD loci are pleiotropic for SSD, extending the findings of Stein et al. (2004) for the RD locus on Chromosome 3. [ABSTRACT FROM AUTHOR]

Measures of component reading and language skills, executive functions, and processing speed were administered to groups of children with attention deficit hyperactivity disorder (ADHD; n = 113), reading disability (RD; n = 109), both RD and ADHD (n = 64), and neither RD nor ADHD (n = 151). Groups with RD exhibited pronounced deficits on all measures of component reading and language skills, as well as significant weaknesses on measures of verbal working memory, processing speed, and response inhibition. Groups with ADHD exhibited weaknesses on all response-inhibition and processing speed tasks and were impaired on some measures of component reading skills and verbal working memory. The group with comorbid RD and ADHD exhibited the combination of the deficits in the RD-only and ADHD-only groups, providing evidence against the phenocopy and cognitive subtype hypotheses as explanations for the co-occurrence of RD and ADHD. Slow and variable processing speed was characteristic of all 3 clinical groups, suggesting that measures of this domain may be useful for future studies that search for the common genes that increase susceptibility to RD and ADHD. [ABSTRACT FROM AUTHOR]

The existing literature has conflicting findings about the literacy outcome of children with speech sound disorders (SSD), which may be due to the heterogeneity within SSD. Previous studies have documented that two important dimensions of heterogeneity are the presence of a comorbid language impairment (LI) and the persistence of SSD, but these factors have not been examined separately. The current study used a 2 × 2 MANOVA design (with follow-up MANCOVAs) to examine how a comorbid language impairment (LI) and the persistence of SSD relate to pre-literacy skills in a sample of 5- to 6-year-old children with SSD. Significant main effects for persistent SSD and LI were obtained, such that each factor was associated with worse performance on pre-literacy tasks, particularly those assessing phonological awareness (even with nonverbal IQ covaried). In addition, even SSD children with normalized speech without LI were found to have deficits on phonological awareness tasks relative to control participants. These results suggest that a history of SSD and comorbid LI are strong correlates of pre-literacy deficits. [ABSTRACT FROM AUTHOR]

This study investigate the relationship between phoneme awareness and rapid naming skills and subsequent reading and spelling ability in two developmental periods; kindergarten to Grade 1 and to Grade 1 to Grade 2. Two groups of children participated in the study: children at high and children at low familial risk of developmental dyslexia. The results are consistent with previous findings that both phoneme awareness and rapid naming play an important role in early literacy acquisition in an alphabetic writing system. However, relative to phoneme awareness, rapid naming plays a modest role. In this study, an unambiguous specific effect for rapid naming was found only among the children in the high-risk group. Furthermore, even among these children, the effect of rapid naming was limited to rapid naming of letters and digits and to the second developmental period investigated. The implications of these results for understanding the role played by rapid naming and phoneme awareness in alphabetic literacy acquisition are discussed. [ABSTRACT FROM AUTHOR]

The article presents the text of an acceptance speech given by the author on the occasion of receiving the Samuel Torrey Orton Award. The author is very touched and very grateful for this award. He said that he would not have been there to receive the award had it not been for the help and support of many others, including his family and the staff and students in his laboratory. Although he does not have the time to thank everyone individually, he does want to highlight the role of some. He wanted to thank the International Dyslexia Association, for its support and inspiration.

Investigates the etiological relationship between two disorders, dyslexia and reading disability (RD) and phonological disorder (PD). Suggestion that the disorders overlap at symptomatic, cognitive and etiological levels of analysis; Evidence that RD and PD run together in families; Finding that the two disorders are coheritable, indicating that the finding of cofamiliarity of RD and PD is at least partially driven by genetic influences.

Typically developing infants show a reliable developmental sequence of emergence of early social-cognitive skills, such as joint attention, communicative gestures, gaze and point following, imitation, and referential language. First infants share others' attention, then they follow others' attention and then behavior, and then they direct others' attention and then behavior. The current study used a series of tests from a study of typically developing infants (Carpenter, Nagell, & Tomasello, 1998) to investigate interrelations among these social-cognitive skills in young children with autism and children with other developmental delays. Tests of object permanence, spatial relations, facial and manual imitation, and executive function also were included. We found that for most children with autism, unlike other children, tests involving others' attention were more difficult than tests involving others' behavior. However, within the domains of attention and behavior, the typical pattern of sharing, then following, and then directing was evident. There were several positive intercorrelations among the social-cognitive skills (as there were for typically developing infants), but there also was some evidence of individual differences in patterns. Implications for theories of social-cognitive and language development are discussed. [ABSTRACT FROM AUTHOR]

Many studies have shown that children with autism have difficulty understanding the thoughts and beliefs of other people. However, little research has been conducted on what these children understand about simpler mental states such as intentions. The current study tested the understanding of others' intentions in 2 1/2- to 5-year-old children with autism and a control group of children with other developmental delays. We used Meltzoff's (1995) test of understanding of others' unfulfilled intentions in an imitation context, with an additional “End State” condition. We found no significant between-group differences on any measure involving the understanding of others' intentions. Although within-group patterns suggested that children with autism may have a slightly less complex understanding of others' intentions than do other children, it was clear that any deficits these children showed in this area were not as marked as those they typically show on traditional theory of mind tasks. [ABSTRACT FROM AUTHOR]

Recent research on the DSM-IV subtypes of attention-deficit/hyperactivity disorder (ADHD) has demonstrated that the subtypes differ in demographic characteristics, types of functional impairment, and profiles of comorbidity with other childhood disorders. However, little research has tested whether the subtypes differ in underlying neuropsychological deficits. This study compared the neuropsychological profiles of children without ADHD (n = 82) and children who met symptom criteria for DSM-IV Predominantly Inattentive subtype (ADHD-IA; n = 67), Predominantly Hyperactive Impulsive subtype (ADHD-HI; n = 14), and Combined subtype (ADHD-C; n = 33) in the areas of processing speed, vigilance, and inhibition. We hypothesized that children with elevations of inattention symptoms (ADHD-IA and ADHD-C) would be impaired on measures of vigilance and processing speed, whereas children with significant hyperactivity/impulsivity (ADHD-HI and ADHD-C) would be impaired on measures of inhibition. Contrary to prediction, symptoms of inattention best predicted performance on all dependent measures, and ADHD-IA and ADHD-C children had similar profiles of impairment. In contrast, children with ADHD-HI were not significantly impaired on any dependent measures once subclinical symptoms of inattention were controlled. Our results do not support distinct neuropsychological deficits in ADHD-IA and ADHD-C children, and suggest that symptoms of inattention, rather than symptoms of hyperactivity/impulsivity, are associated with neuropsychological impairment. [ABSTRACT FROM AUTHOR]

In a 3-year longitudinal study, middle- to upper-middle-class preschool children at high family risk (HR group, N = 67) and low family risk (LR group, N = 57) for dyslexia (or reading disability, RD), were evaluated yearly from before kindergarten to the end of second grade. Both phonological processing and literacy skills were tested at each of four time points. Consistent with the well-known familiarity of RD, 34% of the HR group compared with 6% of the LR group became RD. Participants who became RD showed deficits in both implicit and explicit phonological processing skills at all four time points, clearly indicating a broader phonological deficit than is often found at older ages. The predictors of literacy skill did not vary by risk group. Both risk groups underwent a similar developmental shift from letter-name knowledge to phoneme awareness as the main predictor of later literacy skill. This shift, however, occurred 2 years later in the HR group. Familial risk was continuous rather than discrete because HR children who did not become RD performed worse than LR non-RD children on some phonological and literacy measures. Finally, later RD could be predicted with moderate accuracy at age 5 years, with the strongest predictor being letter-name knowledge. [ABSTRACT FROM AUTHOR]

Questions the utility of assuming modularity, as it examines a paradigmatic double dissociation of reading modules. General problems illustrated by reading modules; Introduction of the double dissociation as a methodological tool; Assumptions that underlie the use of double dissociation.

This study investigated the association between reading disability (RD) and internalizing and externalizing psychopathology in a large community sample of twins with ( NO= 209) and without RD ( NO= 192). The primary goals were to clarify the relation between RD and comorbid psychopathology, to test for gender differences in the behavioral correlates of RD, and to test if common familial influences contributed to the association between RD and other disorders. Results indicated that individuals with RD exhibited significantly higher rates of all internalizing and externalizing disorders than individuals without RD. However, logistic regression analyses indicated that RD was not significantly associated with symptoms of aggression, delinquency, oppositional defiant disorder, or conduct disorder after controlling for the significant relation between RD and ADHD. In contrast, relations between RD and symptoms of anxiety and depression remained significant even after controlling for comorbid ADHD, suggesting that internalizing difficulties may be specifically associated with RD. Analyses of gender differences indicated that the significant relation between RD and internalizing symptoms was largely restricted to girls, whereas the association between RD and externalizing psychopathology was stronger for boys. Finally, preliminary etiological analyses suggested that common familial factors predispose both probands with RD and their non-RD siblings to exhibit externalizing behaviors, whereas elevations of internalizing symptomatology are restricted to individuals with RD. [ABSTRACT FROM AUTHOR]

The reliability and validity of a revised version of Finucci's (1982) Reading History Questionnaire was examined in two adult samples. One sample included 84 adults from an ongoing study of familial dyslexia, and a second sample was composed of parents of 107 children from a longitudinal study of reading development. Internal consistency was demonstrated by Cronbach's alphas of .94 and .92 in the two samples. Test-retest reliability was demonstrated by significant correlations (.87 and .84 in the two samples) over several years between an earlier and revised form of the questionnaire. Validity was demonstrated via (a) correlations between the questionnaire score and reading measures (rs = .57-.70), (b) the results of a discriminant function analysis that used questionnaire scores to predict reading disability diagnosis, and (c) the finding that the questionnaire had substantial incremental validity in predicting reading skill in a hierarchical regression analysis that first entered IQ and SES. These results indicated that the questionnaire is both reliable and valid. [ABSTRACT FROM AUTHOR]

The heritable nature of reading disability has been well documented (DeFries & Alarcon, 1996), and possible abnormalities of brain structures have been associated with the disorder (Filipek, 1995). However, the etiology of individual differences in morphological brain measures has not been examined extensively. The purpose of this study was to apply behavioral genetic methods to assess the etiology of individual differences in neuroanatomical structures. Measures of reading performance, cognitive ability, and magnetic resonance imaging scans were obtained from 25 monozygotic (MZ) and 23 same-sex dizygotic (DZ) twin pairs with reading disability, and 9 MZ and 9 DZ control twin pairs participating in the Colorado Learning Disabilities Research Center. Results obtained from multiple regression analyses (DeFries & Fulker, 1985, 1988) of these twin data indicated that individual differences in the size of most cortical and subcortical structures were largely due to heritable influences. Moreover, estimates of heritability did not change appreciably after controlling for IQ and total brain size. [ABSTRACT FROM AUTHOR]

A community sample of 373 8 to 18 year-old twin pairs in which at least one twin in each pair exhibited a history of learning difficulties was utilized to examine the etiology of inattention and hyperactivity/impulsivity (hyp/imp). Symptoms of attention-deficit/hyperactivity disorder (ADHD) were assessed by the DSM-III Diagnostic Interview for Children and Adolescents. Inattention and hyp/imp composite scores were created based on results of a factor analysis. Results indicated that extreme ADHD scores were almost entirely attributable to genetic influences across several increasingly extreme diagnostic cutoff scores. Extreme inattention scores were also highly heritable whether or not the proband exhibited extreme hyp/imp. In contrast, the heritability of extreme hyp/imp increased as a linear function of the number of inattention symptoms exhibited by the proband. This finding suggests that extreme hyp/imp may be attributable to different etiological influences in individuals with and without extreme inattention. If this result can be replicated in other samples, it would provide evidence that the hyp/imp symptoms exhibited by individuals with Combined Type ADHD and Predominantly Hyp/Imp Type ADHD may be attributable to different etiological influences. [ABSTRACT FROM AUTHOR]

This study used a community sample of 494 twins with a reading disability (223 girls, 271 boys) and 373 twins without a reading disability (189 girls, 184 boys) to assess the relation between reading disability (RD) and attention-deficit/hyperactivity disorder (ADHD). Symptoms of DSM-III and DSM-IV ADHD were classified into symptoms of inattention and symptoms of hyperactivity-impulsivity (H/I). Results indicated that individuals with RD were more likely than individuals without RD to meet criteria for ADHD and that the association between RD and ADHD was stronger for symptoms of inattention than for symptoms of H/I. Parents and teachers reported similar rates of ADHD, suggesting that ADHD symptoms were pervasive across settings and were not solely attributable to academic frustration. Analyses of possible gender differences revealed that RD was significantly associated with inattention in both girls and boys but associated with H/I only in boys. This difference may provide a partial explanation for the discrepancy between the gender ratio obtained in referred (approximately 4 boys to 1 girl) and nonreferred (1.2 to 1.5 boys to 1 girl) samples of individuals with RD. Specifically, the hyperactive and impulsive behaviors exhibited by boys with RD may be more disruptive than the inattentive behaviors exhibited by girls and may therefore precipitate more frequent referrals for clinical attention. [ABSTRACT FROM AUTHOR]

Although it is well known that there is considerable variation among individuals in the size of the human brain, the etiology of less extreme individual differences in brain size is largely unknown. We present here data from the first large twin sample (N=132 individuals) in which the size of brain structures has been measured. As part of an ongoing project examining the brain correlates of reading disability (RD), whole brain morphometric analyses of structural magnetic response image (MRI) scans were performed on a sample of adolescent twins. Specifically, there were 25 monozygotic (MZ) and 23 dizygotic (DZ) pairs in which at least one member of each pair had RD and 9 MZ and 9 DZ pairs in which neither member had RD. We first factor-analyzed volume data for 13 individual brain structures, comprising all of the neocortex and most of the subcortex. This analysis yielded two factors ("cortical" and "subcortical") that accounted for 64% of the variance. We next tested whether genetic and environmental influences on brain size variations varied for these two factors or by hemisphere. We computed intraclass correlations within MZ and DZ pairs in each sample for the cortical and subcortical factor scores, for left and right neocortex, and for the total cerebral volume. All five MZ correlations were substantial (r’s=.78 to .98) and significant in both samples, as well as being larger than the corresponding DZ correlations, (r’s=0.32 to 0.65) in both samples. The MZ– DZ difference was significant for 3 variables in the RD sample and for one variable in the smaller control sample. These results indicate significant genetic influences on these variables. The magnitude of genetic influence did not vary markedly either for the 2 factors or the 2 hemispheres. There was also a positive correlation between brain size and full-scale IQ, consistent with the results of earlier studies. The total cerebral volume was moderately correlated (r=.42, p<.01, two-tailed) with full-scale IQ in the RD sample; there was a similar trend in the smaller control sample (r=.31, p<.07, two-tailed). Corrections of similar magnitude were found between the subcortical factor and full-scale IQ, whereas the results for the cortical factor (r=.16 and .13) were smaller and not significant. In sum, these results provide evidence for the heritability of individual differences in brain size which do not vary markedly by hemisphere or for neocortex relative to subcortex. Since there are also correlations between brain size and full-scale IQ in this sample, it is possible that genetic influences on brain size partly contribute to individual differences in IQ. [ABSTRACT FROM AUTHOR]

The executive dysfunction hypothesis of autism has received support from most studies of older people with autism; however, studies of young children have produced mixed results. Two studies are presented that compare the performance of preschoolers with autism (mean = 51 months/4.3 years of age) to a control group matched on age, and verbal and nonverbal ability. The first study (n = 18 autism and 17 control) found no group differences in performance on 8 executive function tasks (A not B, Object Retrieval, A not B with Invisible Displacement, 3-Boxes Stationary and Scrambled, 6-Boxes Stationary and Scrambled, and Spatial Reversal), but did find that children with autism initiated fewer joint attention and social interaction behaviors. The second (longitudinal) study of a subset of the children (n = 13 autism and 11 control) from the first study found that neither groups' performance on Spatial Reversal changed significantly over the course of a year. The results of these studies pose a serious challenge to the executive dysfunction hypothesis of autism. [ABSTRACT FROM AUTHOR]

Presents a study which examined the profile of psychiatric comorbidity associated with the dimensions and subtypes of DSM-IV attention-deficit/hyperactivity disorder in a nonreferred sample of twins. Methodology of the study; Results and discussion; Conclusions.

PENNINGTON, BRUCE F.; VAN ORDEN, GUY C.; SMITH, SHELLEY D.; GREEN, PHYLLIS A.; and HAITH, MARSHALL M. Phonological Processing Skills and Deficits in Adult Dyslexics. CHILD DEVELOPMENT, 1990, 61, 1753-1778. This article presents 4 experiments aimed at defining the primary underlying phonological processing deficit(s) in adult dyslexia. 5 phonological processes, all involving spoken language, were studied: phoneme perception, phoneme awareness, lexical retrieval of phonology, articulatory speed, and phonetic coding in verbal short-term memory. 2 differently ascertained adult dyslexic groups, familial dyslexics (n = 15) and clinic dyslexics (n = 15), were the subjects in each experiment. These dyslexic groups were chosen because deficits that persist until adulthood and that are found in differently ascertained dyslexic groups are more likely to be primary. Each dyslexic group was compared to 2 control groups, chronological age (CA) controls who were similar in age and sex, and younger reading age (RA) controls who were similar in reading age and sex. The main finding was a clear deficit in phoneme awareness in both dyslexic groups, with each dyslexic group performing significantly worse than both CA and RA controls. Moreover, performance on the 2 phoneme awareness tasks together uniquely accounted for substantial variance in nonword reading. The clinic but not the familial dyslexics appeared to have an additional deficit in verbal short-term memory. No clear deficits were found in either dyslexic group in phoneme perception, lexical retrieval, or articulatory speed. [ABSTRACT FROM PUBLISHER]

WELSH, MARILYN C.; PENNINGTON, BRUCE F.; OZONOFF, SALLY; ROUSE, BOBBYE; and MCCABE, EDWARD R. B. Neuropsychology of Early-treated Phenylketonuria: Specific Executive Function Deficits. CHILD DEVELOPMENT, 1990, 61, 1697-1713. This study explored the hypothesis that children with early-treated phenylketonuria (PKU) are selectively impaired on executive function measures, even when still on diet. The rationale for this hypothesis is that even mild elevations in phenylalanine (Phe) can lead to lower central levels of biogenic amines, including dopamine (DA). We hypothesize that this mild DA depletion causes subtle prefrontal dysfunction, which in turn affects executive functions such as set maintenance, planning, and organized search. 11 preschool early-treated PKU children (M age = 4.64) and a sample of age- and IQ-matched unaffected peers (n = 11) were evaluated on a battery of executive function (EF) measures. In addition, a "non-executive function" task, recognition memory, was administered to all subjects. Group comparisons demonstrated that PKU children were significantly impaired on an executive function composite score; there were no group differences, however, in recognition memory. These results supported the hypothesized specific deficit in executive function. Furthermore, within the PKU group the executive function composite score was significantly negatively correlated with concurrent phenylalanine levels, even after controlling for the correlation between IQ and executive function skills. This second finding provides support for the proposed biochemical mechanism underlying the specific cognitive deficits. [ABSTRACT FROM PUBLISHER]