Comorbidity of reading disabilities and ADHD: Structural and functional brain characteristics

The underlying neuropsychological and neural correlates of the impaired Chinese reading skills in children with attention deficit hyperactivity disorder

Impaired basic academic skills (e.g., word recognition) are common in children with Attention Deficit Hyperactivity Disorder (ADHD). The underlying neuropsychological and neural correlates of impaired Chinese reading skills in children with ADHD have not been substantially explored. Three hundred and two children with ADHD (all medication-naïve) and 105 healthy controls underwent the Chinese language skill assessment, and 175 also underwent fMRI scans (84 ADHD and 91 controls). Between-group and mediation analyses were applied to explore the interrelationships of the diagnosis of ADHD, cognitive dysfunction, and impaired reading skills. Five ADHD-related brain functional networks, including the default mode network (DMN) and the dorsal attention network (DAN), were built using predefined regions of interest. Voxel-based group-wise comparisons were performed. The ADHD group performed worse than the control group in word-level reading ability tests, with lower scores in Chinese character recognition (CR) and word chains (WS) (all P < 0.05). With full-scale IQ and sustained attention in the mediation model, the direct effect of ADHD status on the CR score became insignificant (P = 0.066). The underlying neural correlates for the orthographic knowledge (OT) and CR differed between the ADHD and the control group. The ADHD group tended to recruit more DMN regions to maintain their reading performance, while the control group seemed to utilize more DAN regions. Children with ADHD generally presented impaired word-level reading skills, which might be caused by impaired sustained attention and lower IQ. According to the brain functional results, we infer that ADHD children might utilize a different strategy to maintain their orthographic knowledge and character recognition performance.

Examining the relationship between psychosocial adversity and inhibitory control: an fMRI study of children growing up in extreme poverty

Exposure to psychosocial adversity (PA) is associated with poor behavioral, physical, and mental health outcomes in adulthood. Growing evidence suggests that deficits in executive functions may in part moderate these outcomes, with inhibitory control as an example of such a putative moderator. However, much of the literature examining the development of inhibitory control has been based on children in higher resource environments, and little is known how growing up in a low resource setting might exacerbate the link between inhibitory control and health outcomes. In this context we collected fMRI data during a Go/No-Go inhibitory control task and PA variables for 68 children 5 to 7 years of age living in Dhaka, Bangladesh, an area with a high prevalence of PA. The children's mothers completed behavioral questionnaires to assess the child's PA and their own PA. Whole-brain activation underlying inhibitory control was examined using the No-Go versus Go contrast, and associations with PA variables were assessed using whole-brain regressions. Childhood neglect was associated with weaker activation in the right posterior cingulate, whereas greater family conflict, economic stress, and maternal PA factors were associated with greater activation in the left medial frontal gyrus, right superior and middle frontal gyrus, and left cingulate gyrus. These data suggest that neural networks supporting inhibitory control processes may vary as a function of exposure to different types of PA, particularly between those related to threat and deprivation. Furthermore, increased activation in children with greater PA may serve as a compensatory mechanism, allowing them to maintain similar behavioral task performance.

ADDing up?

OBJECTIVE

To hypothesise that a possible increased prevalence of adult-onset attention-deficit disorder (ADD) and attention-deficit hyperactivity disorder (ADHD) may reflect mobile technology and digital media use being an aetiological factor.

CONCLUSIONS

Data and clinical observations support but do not prove the hypothesis.

Sensory temporal sampling in time: an integrated model of the TSF and neural noise hypothesis as an etiological pathway for dyslexia

Much progress has been made in research on the causal mechanisms of developmental dyslexia. In recent years, the "temporal sampling" account of dyslexia has evolved considerably, with contributions from neurogenetics and novel imaging methods resulting in a much more complex etiological view of the disorder. The original temporal sampling framework implicates disrupted neural entrainment to speech as a causal factor for atypical phonological representations. Yet, empirical findings have not provided clear evidence of a low-level etiology for this endophenotype. In contrast, the neural noise hypothesis presents a theoretical view of the manifestation of dyslexia from the level of genes to behavior. However, its relative novelty (published in 2017) means that empirical research focused on specific predictions is sparse. The current paper reviews dyslexia research using a dual framework from the temporal sampling and neural noise hypotheses and discusses the complementary nature of these two views of dyslexia. We present an argument for an integrated model of sensory temporal sampling as an etiological pathway for dyslexia. Finally, we conclude with a brief discussion of outstanding questions.

Left-dominance for resting-state temporal low-gamma power in children with impaired word-decoding and without comorbid ADHD

One theory of the origins of reading disorders (i.e., dyslexia) is a language network which cannot effectively 'entrain' to speech, with cascading effects on the development of phonological skills. Low-gamma (low-γ, 30-45 Hz) neural activity, particularly in the left hemisphere, is thought to correspond to tracking at phonemic rates in speech. The main goals of the current study were to investigate temporal low-γ band-power during rest in a sample of children and adolescents with and without reading disorder (RD). Using a Bayesian statistical approach to analyze the power spectral density of EEG data, we examined whether (1) resting-state temporal low-γ power was attenuated in the left temporal region in RD; (2) low-γ power covaried with individual reading performance; (3) low-γ temporal lateralization was atypical in RD. Contrary to our expectations, results did not support the hypothesized effects of RD status and poor decoding ability on left hemisphere low-γ power or lateralization: post-hoc tests revealed that the lack of atypicality in the RD group was not due to the inclusion of those with comorbid attentional deficits. However, post-hoc tests also revealed a specific left-dominance for low-γ rhythms in children with reading deficits only, when participants with comorbid attentional deficits were excluded. We also observed an inverse relationship between decoding and left-lateralization in the controls, such that those with better decoding skills were less likely to show left-lateralization. We discuss these unexpected findings in the context of prior theoretical frameworks on temporal sampling. These results may reflect the importance of real-time language processing to evoke gamma rhythms in the phonemic range during childhood and adolescence.

Early predictors in language-based learning disabilities: a bibliometric analysis

Introduction

Language-based learning disabilities (LBLD) refers to a spectrum of neurodevelopmental-associated disorders that are characterized by cognitive and behavioral differences in comprehending, processing and utilizing spoken and/or written language. The focus of this work was on identifying early predictors of three main specific LBLD including dyslexia, dyscalculia, and dysgraphia.

Methods

The Web of Science (WoS) was searched for literature related to (neurocognitive, neurophysiological, and neuroimaging) measurements used to identify early predictors of LBLD from 1991 to 25 October 2021. A retrospective bibliometric analysis was performed to analyze collaboration among countries, institutions, authors, publishing journals, reference co-citation patterns, keyword co-occurrence, keyword clustering, and burst keywords using Biblioanalytics software.

Results

In total, 921 publications related to the identification of LBLD using (neurocognitive, neurophysiological, and neuroimaging) modalities were included. The data analysis shows a slow growth in research on the topic in the 90s and early 2000 and growing trend in recent years. The most prolific and cited journal is Neuroimage, followed by Neuropsychologia. The United States and Finland's Universities Jyvaskyla and Helsinki are the leading country and institution in this field, respectively. "Neuroimaging," "brain," "fMRI," "cognitive predictor," "comorbidity," "cortical thickness" were identified as hotspots and trends of (neurocognitive, neurophysiological, and neuroimaging) modalities in the identification of LBLD.

Discussion

Early predictors of LBLDs would be useful as targets for specific prevention and intervention programs to be implemented at very young ages, which could have a significant clinical impact. A novel finding of neuroimaging predictors combined with neurocognitive and neuropsychological batteries may have implications for future research.

Prevalence and trends of developmental disabilities among US children and adolescents aged 3 to 17 years, 2018-2021

Developmental disabilities prevalence seem to be high in countries around the world. It's worth understanding the most recent prevalence and trends of developmental disabilities. The objective of this study is to examine the prevalence and trends of developmental disabilities of US children and adolescents. A total of 26,422 individuals aged 3-17 years were included. Annual data were examined from the National Health Interview Survey (2018-2021). Weighted prevalence for each of the selected developmental disabilities were calculated. The prevalence of any developmental disabilities in individuals was 16.65% (95% CI 16.03-17.26%), prevalence of attention deficit/hyperactivity disorder (ADHD), learning disability (LD), autism spectrum disorder (ASD), intellectual disability (ID), and other developmental delay were 9.57% (95% CI 9.09-10.06%), 7.45% (95% CI 7.00-7.89%), 2.94% (95% CI 2.67-3.21%), 1.72% (95% CI 1.51-1.93%), and 5.24% (95% CI 4.89-5.59%), respectively. Significant increases were observed for other developmental delay (4.02-6.05%) and co-occurring LD & ID (1.03-1.82%). Findings form this study highlight a high prevalence of any developmental disabilities, although no significant increase was observed. The prevalence of other developmental delay and co-occurring LD & ID were significantly increased. Further investigation is warranted to assess potentially modifiable risk factors and causes of developmental disabilities.

Genetic architecture of ADHD and overlap with other psychiatric disorders and cognition-related phenotypes

Attention-deficit/hyperactivity disorder (ADHD) co-occurs with many other psychiatric disorders and traits. In this review, we summarize and interpret the existing literature on the genetic architecture of these comorbidities based on hypothesis-generating approaches. Quantitative genetic studies indicate that genetic factors play a substantial role in the observed co-occurrence of ADHD with many different disorders and traits. Molecular genetic correlations derived from genome-wide association studies and results of studies based on polygenic risk scores confirm the general pattern but provide effect estimates that are smaller than those from twin studies. The identification of the specific genetic variants and biological pathways underlying co-occurrence using genome-wide approaches is still in its infancy. The first analyses of causal inference using genetic data support causal relationships between ADHD and comorbid disorders, although bidirectional effects identified in some instances point to complex relationships. While several issues in the methodology and inferences from the results are still to be overcome, this review shows that the co-occurrence of ADHD with many psychiatric disorders and traits is genetically interpretable.

Psycholinguistic profiling of children with sluggish cognitive tempo

Language disorders are frequently comorbid with attention deficit/hyperactivity disorder (ADHD). Sluggish cognitive tempo (SCT), a second attention disorder, may potentially explain some of the links between language disorders and ADHD. In this study we examined the psycholinguistic abilities of 207 children (mean age 7;10) with and without clinically significant levels of SCT symptoms to determine the degree to which symptoms of language disorder co-occur in cases of SCT. Analyses of children's tense-marking, nonword repetition, and sentence recall indicated that deficits in these areas were not associated with SCT. Instead, SCT appears to be more closely aligned with features of social (pragmatic) communication disorder.

Exploring Teachers' Knowledge and Attitudes Toward Attention Deficit Hyperactivity Disorder and Its Treatment in a District of Turkey

Background Teachers are pivotal in integrating children with attention deficit hyperactivity disorder (ADHD) into academic and social contexts. Their comprehension of and attitudes toward ADHD significantly influence the inclusion of these children. This study was conducted to assess teachers' knowledge, attitudes, and perceptions about ADHD and its treatment within a representative sample from Turkey. Methods An online self-administered questionnaire was formulated to gauge teachers' knowledge, attitudes, and perceptions related to ADHD and its treatment. Results Of the respondents, 57.7% accurately identified that ADHD is more commonly present in boys. Furthermore, a majority of teachers (60.8%) correctly answered the question related to the comorbidity of ADHD and learning disabilities. However, 20.3% of teachers believed that ADHD medications were addictive, with 9.7% expressing reluctance to use such treatment for their children if needed. Conclusion The results highlight the need for revising the current training curricula for novice teachers and providing additional training for experienced teachers. Such initiatives should aim to rectify any negative perceptions and attitudes toward ADHD held by teachers.

[Application of Preschool Auditory Processing Assessment Scale in children with attention deficit hyperactivity disorder]

OBJECTIVES

To investigate the characteristics of auditory processing (AP) in preschool children with attention deficit hyperactivity disorder (ADHD) using Preschool Auditory Processing Assessment Scale (hereafter referred to as "auditory processing scale").

METHODS

A total of 41 children with ADHD and 41 typically developing (TD) children were assessed using the auditory processing scale, SNAP-IV rating scale, and Conners' Kiddie Continuous Performance Test (K-CPT). The auditory processing scale score was compared between the TD and ADHD groups. The correlations of the score with SNAP-IV and K-CPT scores were assessed.

RESULTS

Compared with the TD group, the ADHD group had significantly higher total score of the auditory processing scale and scores of all dimensions except visual attention (P<0.05). In the children with ADHD, the attention deficit dimension score of the SNAP-IV rating scale was positively correlated with the total score of the auditory processing scale (rs30=0.531, P<0.05; rs27=0.627, P<0.05) as well as the scores of its subdimensions, including auditory decoding (rs=0.628, P<0.05), auditory attention (rs=0.492, P<0.05), and communication (rs=0.399, P<0.05). The hyperactivity-impulsivity dimension score of the SNAP-IV rating scale was positively correlated with the hyperactivity-impulsivity dimension score of the auditory processing scale (rs=0.429, P<0.05). In the children with ADHD, the attention deficit dimension score of the K-CPT was positively correlated with the total score (rs30=0.574, P<0.05; rs27=0.485, P<0.05) and the hyperactivity-impulsivity dimension score (rs=0.602, P<0.05) of the auditory processing scale.

CONCLUSIONS

Preschool children with ADHD have the risk of AP abnormalities, and the auditory processing scale should be used early for the screening and evaluation of AP abnormalities in children.

Properties of white matter tract diffusivity in children with developmental dyslexia and comorbid attention deficit/hyperactivity disorder

BACKGROUND

Developmental dyslexia (DD) and attention deficit/hyperactivity disorder (ADHD) are highly comorbid neurodevelopmental disorders. Individuals with DD or ADHD have both been shown to have deficits in white matter tracts associated with reading and attentional control networks. However, white matter diffusivity in individuals comorbid with both DD and ADHD (DD + ADHD) has not been specifically explored.

METHODS

Participants were 3rd and 4th graders (age range = 7 to 11 years; SD = 0.69) from three diagnostic groups ((DD (n = 40), DD + ADHD (n = 22), and typical developing (TD) (n = 20)). Behavioral measures of reading and attention alongside measures of white matter diffusivity were collected for all participants.

RESULTS

DD + ADHD and TD groups differed in mean fractional anisotropy (FA) for the left and right Superior Longitudinal Fasciculus (SLF)-Parietal Terminations and SLF-Temporal Terminations. Mean FA for the DD group across these SLF tracts fell between the lower DD + ADHD and higher TD averages. No differences in mean diffusivity nor significant brain-behavior relations were found.

CONCLUSIONS

Findings suggest that WM diffusivity in the SLF increases along a continuum across DD + ADHD, DD, and TD.

Examination of common and unique brain regions for atypical reading and math: a meta-analysis

The purpose of this study is to identify consistencies across functional neuroimaging studies regarding common and unique brain regions/networks for individuals with reading difficulties (RD) and math difficulties (MD) compared to typically developing (TD) individuals. A systematic search of the literature, utilizing multiple databases, yielded 116 functional magnetic resonance imaging and positron emission tomography studies that met the criteria. Coordinates that directly compared TD with either RD or MD were entered into GingerALE (Brainmap.org). An activation likelihood estimate (ALE) meta-analysis was conducted to examine common and unique brain regions for RD and MD. Overall, more studies examined RD (n = 96) than MD (n = 20). Across studies, overactivation for reading and math occurred in the right insula and inferior frontal gyrus for atypically developing (AD) > TD comparisons, albeit in slightly different areas of these regions; however, inherent threshold variability across imaging studies could diminish overlying regions. For TD > AD comparisons, there were no similar or overlapping brain regions. Results indicate there were domain-specific differences for RD and MD; however, there were some similarities in the ancillary recruitment of executive functioning skills. Theoretical and practical implications for researchers and educators are discussed.

Pathogenesis of Comorbid ADHD and Chinese Developmental Dyslexia: Evidence From Eye-Movement Tracking and Rapid Automatized Naming

BACKGROUND

ADHD and Chinese developmental dyslexia (DD) have a very high comorbidity rate; however, which cognitive deficits characterize the comorbidity and when they occur during cognitive processing are still under debate.

METHODS

Rapid automatic naming (RAN) tasks with eye-movement tracking were conducted with 75 children who were typically developing, had comorbid ADHD and DD, had only ADHD, and had only DD.

RESULTS

The clinical groups had longer first fixation durations than the control for RAN digits. Temporal eye-movement measures, such as gaze duration and total reading time, were found to vary between the comorbidity and ADHD groups. Spatial eye-movement measures, such as regression probability and incoming saccade amplitude, differed between the comorbidity and DD groups.

CONCLUSIONS

These results indicate that investigation with eye-movement measures combined with RAN tasks can strengthen the understanding of the pathogenesis of comorbid ADHD and DD.

Shared grey matter correlates of reading and attention

Disorders of reading (developmental dyslexia) and attention (ADHD) have a high rate of comorbidity (25-40%), yet little is known about the neural underpinnings of this phenomenon. The current study investigated the shared and unique neural correlates of reading and attention in 330 typically developing children ages 8-18 from the Philadelphia Neurodevelopmental Cohort. Multiple regression analyses were used to identify regions of the brain where grey matter (GM) volume was associated with reading or attention scores (p < 0.001, cluster FDR p < 0.05). Better attention scores correlated with increased GM in the precuneus and higher reading scores were associated with greater thalamic GM. An exploratory conjunction analysis (p < 0.05, k > 239) found that GM in the caudate and precuneus correlated with both reading and attention scores. These results are consistent with a recent meta-analysis which identified GM reductions in the caudate in both dyslexia and ADHD and reveal potential shared neural correlates of reading and attention.

Longitudinal changes in brain activation underlying reading fluency

Reading fluency-the speed and accuracy of reading connected text-is foundational to educational success. The current longitudinal study investigates the neural correlates of fluency development using a connected-text paradigm with an individualized presentation rate. Twenty-six children completed a functional MRI task in 1st/2nd grade (time 1) and again 1-2 years later (time 2). There was a longitudinal increase in activation in the ventral occipito-temporal (vOT) cortex from time 1 to time 2. This increase was also associated with improvements in reading fluency skills and modulated by individual speed demands. These findings highlight the reciprocal relationship of the vOT region with reading proficiency and its importance for supporting the developmental transition to fluent reading. These results have implications for developing effective interventions to target increased automaticity in reading.

Co-Occurrence of Reading and Writing Difficulties: The Application of the Interactive Dynamic Literacy Model

This article presents the application of the interactive dynamic literacy (IDL) model (Kim, 2020b) toward understanding difficulties in learning to read and write. According to the IDL model, reading and writing are part of communicative acts that draw on largely shared processes and skills as well as unique processes and skills. As such, reading and writing are dissociable but interdependent systems that have hierarchical, interactive, and dynamic relations. These key tenets of the IDL model are applied to the disruption of reading and writing development to explain co-occurrence of reading-writing difficulties using a single framework. The following hypotheses are presented: (a) co-occurrence between word reading and spelling and handwriting difficulties; (b) co-occurrence of dyslexia with written composition difficulties; (c) co-occurrence between reading comprehension and written composition difficulties; (d) co-occurrence of language difficulties with reading difficulties and writing difficulties; (e) co-occurrence of reading, writing, and language difficulties with weak domain-general skills or executive functions such as working memory and attentional control (including attention-deficit/ hyperactivity disorder [ADHD]); and (f) multiple pathways for reading and writing difficulties. Implications are discussed.

“Jing-Ning Granules” Can Alleviate Attention Deficit Hyperactivity Disorder in Rats by Modulating Dopaminergic D2/D1-Like Receptor-Mediated Signaling Pathways

Background

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by attention deficit, hyperactivity, and impulsivity. Jing-Ning Granules (JNG) is a traditional Chinese medicine (TCM) that can alleviate ADHD. Although JNG is commonly used for the effective treatment of ADHD and has obtained the national invention patent, the exact mechanism of action remains unclear.

Objective

In this study, we examined the effect and mechanism of JNG in spontaneously hypertensive rats (SHRs). We hypothesized that JNG affects dopaminergic D2/D1-like receptors and related pathways.

Materials and Methods

Six rat groups were used in the experiment: Wistar-Kyoto rats (WKY, control group) and five SHR groups, including a model group; atomoxetine (ATX, positive control) group; and low, medium, and high-dose JNG groups. The corresponding treatments were daily administered to each group for 6 weeks. A behavioral test, including a step-down test and open field test (OFT), was carried out at the end of treatment. After the behavioral test, all animals were sacrificed, and the brain tissue was collected and analyzed ex vivo; histopathological analysis was performed to assess the pathological changes of the hippocampus; expression of D1-like and D2-like receptors, sensor protein calmodulin (CaM), protein kinase A (PKA), and calcium/calmodulin-dependent serine/threonine protein kinase (CaMKII) in the striatum and hippocampus was measured by western blot and real-time quantitative PCR (RT-PCR); cyclic adenosine monophosphate (cAMP) levels in the striatum were analyzed using an enzyme-linked immunosorbent assay (ELISA), while the level of Ca²⁺ in the striatum was analyzed by a calcium kit.

Results

Our results showed that ATX or JNG could ameliorate the hyperactive/impulsive behavior and cognitive function of ADHD by promoting neuroprotection. Mechanistically, ATX or JNG could prompt the expressions of Dl-like and D2-like receptors and improve the mRNA and protein levels of cAMP/PKA and Ca²⁺/CAM/CAMKII signaling pathways.

Conclusion

These results indicate that JNG can produce therapeutic effects by regulating the balance of D2/D1-like receptor-mediated cAMP/PKA and Ca²⁺/CaM/CaMKII signaling pathways.

Seeking Overlapping Neuroanatomical Alterations between Dyslexia and Attention-Deficit/Hyperactivity Disorder: A Meta-Analytic Replication Study

The present work is a replication article based on the paper “Are there shared neural correlates between dyslexia and ADHD? A meta-analysis of voxel-based morphometry studies” by McGrath and Stoodley (2019). In the original research, the authors used activation likelihood estimation (ALE), a technique to perform coordinate-based meta-analysis (CBMA), to investigate the existence of brain regions undergoing gray matter alteration in association with both attention-deficit/hyper-activity disorder (ADHD) and dyslexia. Here, the same voxel-based morphometry dataset was analyzed, while using the permutation-subject images version of signed differential mapping (PSI-SDM) in place of ALE. Overall, the replication converged with the original paper in showing a limited overlap between the two conditions. In particular, no significant effect was found for dyslexia, therefore precluding any form of comparison between the two disorders. The possible influences of biological sex, age, and medication status were also ruled out. Our findings are in line with literature about gray matter alteration associated with ADHD and dyslexia, often showing conflicting results. Therefore, although neuropsychological and clinical evidence suggest some convergence between ADHD and dyslexia, more future research is sorely needed to reach a consensus on the neuroimaging domain in terms of patterns of gray matter alteration.

Reading performance in children with ADHD: an eye-tracking study

Reading disabilities have a profound impact on the academic performance and achievement of children. Although oculomotor pattern abnormalities during reading in children with dyslexia are well known, those in individuals with attention deficit and hyperactive disorders (ADHD) - who also frequently exhibit a reading impairment - remain largely undetermined. The objective of the present study was to evaluate the peculiarities of oculomotor pattern abnormalities during a reading task. An eye-tracker was used to record eye movements in four distinct groups of children with neurodevelopmental disorders: children with dyslexia, children with ADHD with and without comorbid dyslexia, and in a group of typically developing children (TD). Ninety-six children participated in the study (24 children per group, IQ- and age-matched groups). The duration of fixation, the total reading time, and the number of forward and backward saccades were similar in children with dyslexia and ADHD + dyslexia, but were significantly different from those observed in children with ADHD and with TD. Our findings suggest a link between dyslexia and oculomotor reading impairments in both children with dyslexia and children with ADHD + dyslexia, indicating that the oculomotor pattern in children with ADHD without comorbid dyslexia is similar to that observed in TD children. We suggest that an objective eye movement recording during a reading task could help clinicians to better evaluate the possible presence of comorbid dyslexia in children with ADHD. Furthermore, children with ADHD with and without comorbid dyslexia could also have working memory deficiencies. Further studies are needed to confirm this finding.

Sleep Disturbances in Children with Attentional Deficit Hyperactivity Disorder and Specific Learning Disorders

Sleep disturbances may be a significant source of distress for children with neurodevelopmental disorders, and consequently also for their families. Crucially, sleep disturbances might be influenced by comorbidity. Attention deficit hyperactivity disorder (ADHD) and specific learning disorder (SLD) often co-occur, and consequently, investigating sleep disturbances in children with comorbidity of ADHD and SLD is essential. Our study aimed at detecting sleep difficulties in a group of 74 children with ADHD, 78 children with SLD, and 76 children with ADHD and SLD by using the Sleep Disturbances Scale for Children. The results showed that sleep difficulties emerge more clearly in children with comorbid ADHD and SLD compared to children with only ADHD or SLD. These sleep difficulties were not due to differences in ages and behavioral/emotional problems. In conclusion, evaluating sleep disturbances is important when assessing and managing children with ADHD, SLD, and particularly with the two comorbid conditions, to better understand their difficulties and develop tailored interventions.

Distinctive neural correlates of phonological and reading impairment in fetal alcohol-exposed adolescents with and without facial dysmorphology

Prenatal alcohol exposure (PAE) has been linked to atypical brain and cognitive development, including poor academic performance in reading. This study utilized functional magnetic resonance imaging and diffusion tensor imaging to characterize functional and structural mechanisms mediating reading deficits in 26 adolescents with PAE-related facial dysmorphology (fetal alcohol syndrome (FAS)/partial FAS (PFAS)), 29 heavily-exposed (HE) non-syndromal adolescents, in comparison with 19 typically developing controls. The FAS/PFAS and HE groups were balanced in terms of levels of PAE and reading (dis)ability. While neural alterations in the posterior association cortices were evident in both PAE groups, distinctive neural correlates of reading (dis)abilities were observed between adolescents with and without facial dysmorphology. Specifically, compared to the HE and control groups, the syndromal adolescents showed greater activation in the right precentral gyrus during phonological processing and rightward lateralization in an important reading-related tract (inferior longitudinal fasciculus, ILF), suggesting an atypical reliance on the right hemisphere. By contrast, in the HE, better reading skills were positively correlated with neural activation in the left angular gyrus and white matter organization of the left ILF, although the brain function-behavior relation was weaker than among the controls, suggesting less efficient function of the typical reading network. Our findings provide converging evidence at both the neural functional and structural levels for distinctive brain mechanisms underlying atypical reading and phonological processing in PAE adolescents with and without facial dysmorphology.

Research Review: Language and specific learning disorders in children and their co-occurrence with internalizing and externalizing problems: a systematic review and meta-analysis

BACKGROUND

Some studies suggest that children with language and learning disorders (LLDs) show more internalizing and externalizing problems than their peers. However, the available evidence remains inconsistent, especially regarding the conditions under which these psychological problems occur.

METHODS

We performed a meta-analysis of studies comparing children with LLDs and controls on internalizing (53 independent samples, 135 effect sizes) and externalizing problems (37 independent samples, 61 effect sizes) separately.

RESULTS

Children with LLDs showed higher internalizing (Hedges' g = 0.36) and externalizing problems (Hedges' g = 0.42) than controls did. The group standardized difference in internalizing problems was moderated by the primary disorder, with children with language disorders showing more internalizing problems than those with reading disorders. The severity of the primary disorder, IQ, and age did not moderate Hedge's g between children with LLDs and controls in internalizing and externalizing outcomes. The same pattern was found for gender as a moderator of Hedge's g in internalizing problems, while findings for externalizing problems were inconclusive. The results were consistent when methodological variables were assessed, also for informant, sample size, and geographical area. Clinical samples with LLDs reported higher internalizing problems respect to those with difficulties, but findings on externalizing outcomes were limited. Similarly, results on the presence of additional symptoms in learning and language, self-concept, and socioeconomic status were inconclusive, as few studies reported this information. Results were robust when publication bias, publication year, and study quality were assessed.

CONCLUSIONS

There is evidence that children with LLDs report higher internalizing and externalizing problems than controls do. Children with language disorders seemed more vulnerable to report more internalizing problems, and clinical samples reported higher problems than those with difficulties. For clinical practice, assessment and interventions should target socioemotional skills to support the psychological well-being of children with LLDs.

Reading impairment in adolescents with fetal alcohol spectrum disorders

PURPOSE

To date, research on effects of prenatal alcohol exposure (PAE) has focused on a broad range of cognitive impairments, but relatively few studies have examined effects of PAE on development of reading skills. Although PAE has been linked to poorer reading comprehension, it remains unclear whether this impairment is attributable to deficits in phonological processing, word reading, oral language skills, and/or executive functioning.

METHODS

A comprehensive reading battery was administered to 10 adolescents with fetal alcohol syndrome (FAS); 16 with partial FAS; 30 nonsyndromal heavily-exposed; 49 controls.

RESULTS

PAE was related to poorer reading comprehension but not to single word reading or phonological processing, suggesting that the mechanics of reading are intact in adolescents with fetal alcohol spectrum disorders at this age. PAE-related impairment in reading comprehension was mediated, in part, by deficits in mastery of oral language skills, including vocabulary, language structure, and verbal fluency.

CONCLUSIONS

These results are consistent with research showing that reading comprehension in adolescence relies increasingly on linguistic comprehension abilities, especially once word reading becomes automatic and text complexity increases. Our findings suggest that reading-impaired adolescents with PAE will benefit from intervention programs targeting vocabulary knowledge, language structure, verbal fluency, and reading comprehension skills.

Abnormal Brain Structure Morphology in Early-Onset Schizophrenia

With less exposure to environmental and medication influences, individuals with early-onset schizophrenia (EOS) may provide valuable evidence to study the pathogenesis and phenotypic pattern of schizophrenia.T1-weighted magnetic resonance images were collected in 60 individuals with EOS and 40 healthy controls. Voxel-based morphometry and surface-based morphometry analyzes were performed. Gray matter volume, cortical thickness and cortical surface area were compared between the EOS and healthy controls and among schizophrenia subgroups (with or without family history of schizophrenia). Compared with healthy controls, the EOS group had reduced gray matter volume in the bilateral middle temporal gyrus and reduced cortical thickness in several brain regions. The sporadic early onset schizophrenia and the familial early onset schizophrenia showed different brain structure morphology. These findings suggest that abnormal brain structure morphology, especially in the temporal and frontal lobes, may be an important pathophysiological feature of EOS.

Reading intervention and neuroplasticity: A systematic review and meta-analysis of brain changes associated with reading intervention

Behavioral research supports the efficacy of intervention for reading disability, but the brain mechanisms underlying improvement in reading are not well understood. Here, we review 39 neuroimaging studies of reading intervention to characterize links between reading improvement and changes in the brain. We report evidence of changes in activation, connectivity, and structure within the reading network, and right hemisphere, frontal and sub-cortical regions. Our meta-analysis of changes in brain activation from pre- to post- reading intervention in eight studies did not yield any significant effects. Methodological heterogeneity among studies may contribute to the lack of significant meta-analytic findings. Based on our qualitative synthesis, we propose that brain changes in response to intervention should be considered in terms of interactions among distributed cognitive, linguistic and sensory systems, rather than via a "normalized" vs. "compensatory" dichotomy. Further empirical research is needed to identify effects of moderating factors such as features of intervention programs, neuroimaging tasks, and individual differences among participants.

Altered single-subject gray matter structural networks in drug-naïve attention deficit hyperactivity disorder children

Altered topological organization of brain structural covariance networks has been observed in attention deficit hyperactivity disorder (ADHD). However, results have been inconsistent, potentially related to confounding medication effects. In addition, since structural networks are traditionally constructed at the group level, variabilities in individual structural features remain to be well characterized. Structural brain imaging with MRI was performed on 84 drug‐naïve children with ADHD and 83 age‐matched healthy controls. Single‐subject gray matter (GM) networks were obtained based on areal similarities of GM, and network topological properties were analyzed using graph theory. Group differences in each topological metric were compared using nonparametric permutation testing. Compared with healthy subjects, GM networks in ADHD patients demonstrated significantly altered topological characteristics, including higher global and local efficiency and clustering coefficient, and shorter path length. In addition, ADHD patients exhibited abnormal centrality in corticostriatal circuitry including the superior frontal gyrus, orbitofrontal gyrus, medial superior frontal gyrus, precentral gyrus, middle temporal gyrus, and pallidum (all p < .05, false discovery rate [FDR] corrected). Altered global and nodal topological efficiencies were associated with the severity of hyperactivity symptoms and the performance on the Stroop and Wisconsin Card Sorting Test tests (all p < .05, FDR corrected). ADHD combined and inattention subtypes were differentiated by nodal attributes of amygdala (p < .05, FDR corrected). Alterations in GM network topologies were observed in drug‐naïve ADHD patients, in particular in frontostriatal loops and amygdala. These alterations may contribute to impaired cognitive functioning and impulsive behavior in ADHD.

Examining Distinctive Working Memory Profiles in Chinese Children With Predominantly Inattentive Subtype of Attention-Deficit/Hyperactivity Disorder and/or Reading Difficulties

Although evidence has shown that both RD and ADHD-I children suffer from working memory problems, inconsistencies in impaired modalities have been reported. This study aimed to (1) compare the three WM domains (i.e., verbal WM, visual-spatial WM, and behavioral WM) among pure ADHD-I, pure RD, comorbid ADHD-I+RD, and typical control groups and (2) examine the impact of comorbidity on the three WM domains. A Chinese sample of participants from Hong Kong included 29 children in the ADHD-I group, 78 children in the RD group, 31 children in the comorbid group (ADHD-I+RD), and 64 children in the TD control group. All participants completed the assessments individually. The findings showed that the children with ADHD-I and/or RD exhibited diverse cognitive profiles. In particular, RD was associated with verbal and visual-spatial working memory deficits, while ADHD-I was associated with behavioral working memory deficits. Interestingly, the comorbid condition demonstrated additive deficits of the two disorders but with greater deficits in behavioral working memory. These findings support the cognitive subtype hypothesis and provide a clearer picture of the distinctive working memory profiles of different groups, allowing for the development of intervention programs in the future.

The Polygenic Nature and Complex Genetic Architecture of Specific Learning Disorder

Specific Learning Disorder (SLD) is a multifactorial, neurodevelopmental disorder which may involve persistent difficulties in reading (dyslexia), written expression and/or mathematics. Dyslexia is characterized by difficulties with speed and accuracy of word reading, deficient decoding abilities, and poor spelling. Several studies from different, but complementary, scientific disciplines have investigated possible causal/risk factors for SLD. Biological, neurological, hereditary, cognitive, linguistic-phonological, developmental and environmental factors have been incriminated. Despite worldwide agreement that SLD is highly heritable, its exact biological basis remains elusive. We herein present: (a) an update of studies that have shaped our current knowledge on the disorder’s genetic architecture; (b) a discussion on whether this genetic architecture is ‘unique’ to SLD or, alternatively, whether there is an underlying common genetic background with other neurodevelopmental disorders; and, (c) a brief discussion on whether we are at a position of generating meaningful correlations between genetic findings and anatomical data from neuroimaging studies or specific molecular/cellular pathways. We conclude with open research questions that could drive future research directions.

Neuroimaging in attention-deficit/hyperactivity disorder

PURPOSE OF REVIEW

Neuroimaging research on attention-deficit/hyperactivity disorder (ADHD) continues growing in extent and complexity, although it has yet to become clinically meaningful. We review recent MRI research on ADHD, to identify robust findings, current trends and challenges.

RECENT FINDINGS

We identified 40 publications between January 2019 and September 2020 reporting or reviewing MRI research on ADHD. Four meta-analyses have presented conflicting results regarding across-study convergence of functional and resting-state functional (fMRI and R-fMRI) studies on ADHD. On the other hand, the Enhancing NeuroImaging Genetics Through Meta-Analysis international consortium has identified statistically robust albeit small differences in structural brain cortical and subcortical indices in children with ADHD versus typically developing controls. Other international consortia are harnessing open-science efforts and multimodal data (imaging, genetics, phenotypic) to shed light on the complex interplay of genetics, environment, and development in the pathophysiology of ADHD. We note growing research in 'prediction' science, which applies machine-learning analysis to identify biomarkers of disease based on big data.

SUMMARY

Neuroimaging in ADHD is still far from informing clinical practice. Current large-scale, multimodal, and open-science initiatives represent promising paths toward untangling the neurobiology of ADHD.

Effects of Sleep on the Academic Performance of Children with Attention Deficit and Hyperactivity Disorder

Attention deficit and hyperactivity disorder (ADHD) is commonly associated with disordered or disturbed sleep and the association of sleep problems with ADHD is complex and multidirectional. The purpose of this study was to analyze the relationship between sleep and academic performance, comparing children with ADHD and a control group without ADHD. Academic performance in Spanish, mathematics, and a foreign language (English) was evaluated. Different presentations of ADHD were considered as well as the potential difference between weekday and weekend sleep habits. The sample consisted of 75 children aged 6–12 in primary education. Accelerometry was used to study sleep, and school grades were used to gather information about academic performance. The results showed that ADHD influenced the amount of sleep during weekends, the time getting up at the weekends, weekday sleep efficiency, as well as academic performance. Given the effects that were seen in the variables linked to the weekend, it is necessary to consider a longitudinal design with which to determine if there is a cause and effect relationship.

Perfiles conductuales del alumnado con TDAH: Dominios y Subdominios del Cuestionario Five to Fifteen (FTF)

El Trastorno por Déficit de Atención con o sin Hiperactividad (TDAH) es un trastorno neurobiológico en el que se presentan una serie de síntomas o patrones de indicadores más o menos estables como hiperactividad, impulsividad y déficit de atención que se empiezan a manifestar en la infancia, solapados en muchos casos con problemas comórbidos. En este artículo se presenta un estudio empírico, realizado con una muestra de 64 alumnos entre los 5 y 15 años de edad, con diagnóstico clínico en TDAH, cursando estudios desde 3º de Educación Infantil a 4º de Educación Secundaria Obligatoria, con una M de edad 10.27 años (DT=2.76), de los cuales 51 son niños y 13 son niñas. Para el estudio se ha empleado una metodología con técnicas cuantitativas, en la que los participantes fueron evaluados mediante el Cuestionario Five to Fifteen (FTF) de Kadesjö, con un cuestionario cumplimentado por sus padres que ofrece la posibilidad de descubrir los problemas propios de un niño con TDAH y aquellos que se pueden asociar. Se aplica el software SPSS para la obtención de los resultados de los 179 ítems correspondientes a los dominios y subdominios del TDAH. Con estos resultados se pretende definir el perfil de los dominios y subdominios del TDAH a través del cuestionario FTF. Entre los resultados hallados encontramos que algunas de las características clave de los niños que presentan este trastorno son las dificultades de aprendizaje y la problemática de estos niños con la interacción social.

Pediatric ADHD symptom burden relates to distinct neural activity across executive function domains

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent childhood disorder marked by inattention and/or hyperactivity symptoms. ADHD may also relate to impaired executive function (EF), but is often studied in a single EF task per sample. The current study addresses the question of unique vs. overlapping relations in brain activity across multiple EF tasks and ADHD symptom burden. Three in-scanner tasks drawn from distinct EF domains (cognitive flexibility, working memory, and inhibition) were collected from children with and without an ADHD diagnosis (N = 63). Whole-brain activity and 11 regions of interest were correlated with parent reports of inattention and hyperactivity symptoms. Across the three EF domains, brain activity related to ADHD symptom burden, but the direction and location of these associations differed across tasks. Overall, activity in sensory and default mode network regions related to ADHD, and these relations did not consistently overlap across EF domains. We observed both distinct and overlapping patterns for inattention and hyperactivity symptoms. By studying multiple EF tasks in the same sample, we identified a heterogenous neural profile related to attention symptom burden in children. Our results inform ADHD characterization and treatment and explain some of the variable brain results related to EF and ADHD reported in the literature.

Putative protective neural mechanisms in prereaders with a family history of dyslexia who subsequently develop typical reading skills

Developmental dyslexia affects 40-60% of children with a familial risk (FHD+) compared to a general prevalence of 5-10%. Despite the increased risk, about half of FHD+ children develop typical reading abilities (FHD+Typical). Yet the underlying neural characteristics of favorable reading outcomes in at-risk children remain unknown. Utilizing a retrospective, longitudinal approach, this study examined whether putative protective neural mechanisms can be observed in FHD+Typical at the prereading stage. Functional and structural brain characteristics were examined in 47 FHD+ prereaders who subsequently developed typical (n = 35) or impaired (n = 12) reading abilities and 34 controls (FHD-Typical). Searchlight-based multivariate pattern analyses identified distinct activation patterns during phonological processing between FHD+Typical and FHD-Typical in right inferior frontal gyrus (RIFG) and left temporo-parietal cortex (LTPC) regions. Follow-up analyses on group-specific classification patterns demonstrated LTPC hypoactivation in FHD+Typical compared to FHD-Typical, suggesting this neural characteristic as an FHD+ phenotype. In contrast, RIFG showed hyperactivation in FHD+Typical than FHD-Typical, and its activation pattern was positively correlated with subsequent reading abilities in FHD+ but not controls (FHD-Typical). RIFG hyperactivation in FHD+Typical was further associated with increased interhemispheric functional and structural connectivity. These results suggest that some protective neural mechanisms are already established in FHD+Typical prereaders supporting their typical reading development.

Visual Search in Chinese Children With Attention Deficit/Hyperactivity Disorder and Comorbid Developmental Dyslexia: Evidence for Pathogenesis From Eye Movements

In this study, a visual search task was conducted on children with comorbid attention deficit/hyperactivity disorder (ADHD) and developmental dyslexia (DD), children with pure ADHD, and typically developing children to explore the pathogenesis of comorbidity between ADHD and DD. Participants searched for the target character from five characters in each trial during the task. The distractors included orthographically similar characters, homophones, unrelated characters, and characters of a different color (i.e., red). Results showed that the clinical groups produced longer first fixation duration than the control group in all types of distractors. Children with ADHD comorbid DD were also more susceptible to characters with the distracting red color in gaze duration and total viewing time than were children with pure ADHD and healthy controls. The implication of comorbidity (ADHD + DD) on the pathogenesis was discussed. These results may be helpful for the diagnosis and treatment of ADHD with comorbid DD.

Frontal volume as a potential source of the comorbidity between attention-deficit/hyperactivity disorder and reading disorders

Prefrontal volume reductions commonly are demonstrated in ADHD, but the literature examining prefrontal volume in reading disorders (RD) is scant despite their also having executive functioning (EF) deficits. Furthermore, only a few anatomical studies have examined the frontal lobes in comorbid RD/ADHD, though they have EF deficits similar to RD and ADHD. Hence, we examined frontal gyri volume in children with RD, ADHD, RD/ADHD and controls, as well as their relationship to EF for gyri found to differ between groups. We found right inferior frontal (RIF) volume was smaller in ADHD, and smaller volume was related to worse behavioral regulation. Left superior frontal (LSF) volume was larger in RD than ADHD, and its size was negatively related to basic reading ability. Left middle frontal (LMF) volume was largest in RD/ADHD overall. Further, its volume was not related to basic reading nor behavioral regulation but was related to worse attentional control, suggesting some specificity in its EF relationship. When examining hypotheses on the etiology of RD/ADHD, RD/ADHD was commensurate with ADHD in RIF volume and both RD and ADHD in LSF volume (being midway between the groups), consistent with the common etiology hypothesis. Nevertheless, they also had an additional gyrus affected: LMF, consistent with the cognitive subtype hypothesis in its specificity to RD/ADHD. The few other frontal aMRI studies on RD/ADHD supported both hypotheses as well. Given this, future research should continue to focus on frontal morphology in its endeavors to find neurobiological contributors to the comorbidity between RD and ADHD.

Are there shared neural correlates between dyslexia and ADHD? A meta-analysis of voxel-based morphometry studies

BACKGROUND

Dyslexia and Attention-deficit/hyperactivity disorder (ADHD) are highly comorbid neurodevelopmental disorders (estimates of 25-40% bidirectional comorbidity). Previous work has identified strong genetic and cognitive overlap between the disorders, but neural overlap is relatively unexplored. This study is a systematic meta-analysis of existing voxel-based morphometry studies to determine whether there is any overlap in the gray matter correlates of both disorders.

METHODS

We conducted anatomic likelihood estimate (ALE) meta-analyses of voxel-based morphometry studies in which individuals with dyslexia (15 studies; 417 cases, 416 controls) or ADHD (22 studies; 898 cases, 763 controls) were compared to typically developing controls. We generated ALE maps for dyslexia vs. controls and ADHD vs. controls using more conservative (p < .001, k = 50) and more lenient (p < .005, k = 50) thresholds. To determine the overlap of gray matter correlates of dyslexia and ADHD, we examined the statistical conjunction between the ALE maps for dyslexia vs. controls and ADHD vs. controls (false discovery rate [FDR] p < .05, k = 50, 5000 permutations).

RESULTS

Results showed largely distinct gray matter differences associated with dyslexia and ADHD. There was no evidence of statistically significant gray matter overlap at our conservative threshold, and only one region of overlap in the right caudate at our more lenient threshold. Reduced gray matter in the right caudate may be relevant to shared cognitive correlates in executive functioning and/or procedural learning. The more general finding of largely distinct regional differences in gray matter between dyslexia and ADHD suggests that other neuroimaging modalities may be more sensitive to overlapping neural correlates, and that current neuroimaging recruitment approaches may be hindering progress toward uncovering neural systems associated with comorbidity.

CONCLUSIONS

The current study is the first to meta-analyze overlap between gray matter differences in dyslexia and ADHD, which is a critical step toward constructing a multi-level understanding of this comorbidity that spans the genetic, neural, and cognitive levels of analysis.

Mild-to-Moderate Gestational Iodine Deficiency Processing Disorder

This synopsis paper aims to identify if a common pattern of learning and social difficulties can be conceptualized across recent longitudinal studies investigating the influence of mild-to-moderate gestational iodine deficiency (GID) on offspring's optimal cognitive and psycho-social development. The main studies investigated are: The Southampton Women's Study (SWS)-United Kingdom; the Avon Longitudinal Study of Parents and Children (ALSPAC)-United Kingdom; the Gestational Iodine Cohort Longitudinal Study-Tasmania, Australia, and the Danish National Birth Cohort Case-Control Study-Denmark. In contrast to severe GID where there is a global negative impact on neurodevelopment, mild-to-moderate intrauterine iodine deficiency has subtler, but nonetheless important, permanent cognitive and psycho-social consequences on the offspring. This paper links the results from each study and maintains that mild-to-moderate GID is associated with a disorder that is characterized by speed of neural transmitting difficulties that are typically associated with working memory capacity difficulties and attention and response inhibition. The authors maintain that this disorder is better identified as Gestational Iodine Deficiency Processing Disorder (GIDPD), rather than, what to date has often been identified as 'suboptimal development'. The Autistic Spectrum Disorder (ASD), Attention Deficit, Hyperactivity Disorder (ADHD), language and literacy disorders (learning disabilities and dyslexia) are the main manifestations associated with GIDPD. GIDPD is identified on IQ measures, but selectively and mainly on verbal reasoning IQ subtests, with individuals with GIDPD still operating within the 'normal' full-scale IQ range. Greater consideration needs to be given by public health professionals, policy makers and educators about the important and preventable consequences of GID. Specifically, more emphasis should be placed on adequate iodine intake in women prior to pregnancy, as well as during pregnancy and when lactating. Secondly, researchers and others need to further extend, refine and clarify whether GIDPD, as a nosological (medical classification) entity, is a valid disorder and concept for consideration.

Comorbidity of reading disabilities and ADHD: Structural and functional brain characteristics

Reading disabilities (RD) and attention-deficit/hyperactivity disorder (ADHD) are two of the most common developmental disorders. RD and ADHD frequently co-occur, which raises questions about how the disorders interact and to what extent they can be differentiated. To date, the underlying neural mechanisms leading to RD-ADHD comorbidity (COM) are not understood. In this study, structural and functional magnetic resonance imaging (fMRI) were combined with comprehensive behavioral testing in order to characterize the behavior, brain structure, and neural correlates of executive function, phonological processing and reading fluency in 60 children with clinical diagnoses of RD, ADHD, or COM, and controls. Whole-brain analyses of variance were performed on cortical thickness values and on the data of the three fMRI tasks to investigate overall group differences. To validate these findings, a region of interest analysis was performed in regions that have previously been shown to exhibit group differences in children with RD or ADHD using the same paradigms. The neuroimaging results demonstrated structural and functional atypicalities for COM in regions that are frequently associated with deficits in children with isolated ADHD or RD. A combination of shared and distinctive brain alterations between the clinical groups was identified, supporting the multiple deficit model for ADHD, RD, and its comorbidity.