Unraveling Brain Synchronisation Dynamics by Explainable Neural Networks using EEG Signals: Application to Dyslexia Diagnosis.

The electrical activity of the neural processes involved in cognitive functions is captured in EEG signals, allowing the exploration of the integration and coordination of neuronal oscillations across multiple spatiotemporal scales. We have proposed a novel approach that combines the transformation of EEG signal into image sequences, considering cross-frequency phase synchronisation (CFS) dynamics involved in low-level auditory processing, with the development of a two-stage deep learning model for the detection of developmental dyslexia (DD). This deep learning model exploits spatial and temporal information preserved in the image sequences to find discriminative patterns of phase synchronisation over time achieving a balanced accuracy of up to 83%. This result supports the existence of differential brain synchronisation dynamics between typical and dyslexic seven-year-old readers. Furthermore, we have obtained interpretable representations using a novel feature mask to link the most relevant regions during classification with the cognitive processes attributed to normal reading and those corresponding to compensatory mechanisms found in dyslexia.

Number sense deficits in children with developmental dyscalculia, dyslexia, co-occurring disorder and their typically developing peers.

The aim of this study was to explore a number sense deficits in children with developmental dyscalculia, dyslexia, co-occurring disorder and their typically developing peers. A non-symbolic quantity comparison task was used in this study to examine whether children with dyscalculia have number sense deficits. Children aged 10-11 years old from nine primary schools in Taif city, Saudi Arabia, were selected to participate in this study. The children were divided into the dyscalculia group (n = 62), the dyslexia group (n = 60), and co-occurring disorder group (n = 65), and the typically developing peers group (n = 100).4 groups (dyscalculia, dyslexia, co-occurring disorder and typically developing peers group) × 2 stimulus ratio (6:7; 8:12). There were significant differences in non-symbolic quantity comparison tasks between children with dyslexia, co-occurring disorder, and typically developing peers. These results indicate that children with dyscalculia do have number sense deficiencies, but number sense deficiencies are not specific to children with dyscalculia.

Reduced benefit from long-term item frequency contributes to short-term memory deficits in dyslexia.

Dyslexia, a specific difficulty in acquiring proficient reading, is also characterized by reduced short-term memory (STM) capacity. Extensive research indicates that individuals with developmental dyslexia (IDDs) benefit less from exposure, and this hampers their long-term knowledge accumulation. It is well established that long-term knowledge has a great effect on performance in STM tasks, and thus IDDs' reduced benefit of exposure could potentially reduce their relative performance in such tasks, especially when frequent items, such as digit-words, are used. In this study we used a standard, widely used, STM assessment: the Digit Span subtest from the Wechsler Adult Intelligence Scale. The task was conducted twice: in native language and in second language. As exposure to native language is greater than exposure to second language, we predicted that IDDs' performance in the task administered in native language will reveal a larger group difference as compared to second language, due to IDDs' reduced benefit of item frequency. The prediction was confirmed, in line with the hypothesis that reduced STM in dyslexia to a large extent reflects reduced benefits from long-term item frequency and not a reduced STM per se.

Automatic metaphor processing in developmental dyslexia.

INTRODUCTION: Previous research found metaphor impairments with dyslexia; however, it is unclear if difficulties are due to initial activation of the metaphorical meaning or to subsequent discourse integration processes. The study examines the presence of early automatic processing of metaphors in adults with developmental dyslexia, considering the role of executive functions and metaphor familiarity. METHODS: Using a sentence recall task and a semantic judgment task from the Metaphor Interference Effect (MIE) paradigm, we evaluated two early stages of metaphor comprehension, namely the generation of the figurative meaning and the suppression of the literal meaning. High and low familiar metaphors, and their scrambled counterparts, were aurally presented to participants, who were asked to judge whether sentences were literally true or literally false. Afterwards, they were provided ten minutes to recall the sentences they heard to verify the depth of processing for each type of stimulus. A total of 26 participants with dyslexia were included in the experimental group, and 31 in the control group. RESULTS: Individuals with dyslexia showed a MIE and an accuracy rate that are similar to participants without dyslexia. Inhibition correlated with the MIE size only for high familiar metaphors, and working memory seemed to play no role in the process. In the recall task, both groups demonstrated a better encoding of the metaphorical sentences compared to scrambled metaphors, but participants with dyslexia recalled less metaphors than did the control group, showing that metaphors are no exception to the limitations in sentence retrieval typically found in dyslexia. CONCLUSIONS: Our findings suggest that individuals with dyslexia are comparable to participants without dyslexia in their ability to automatically compute metaphorical meanings. Thus, difficulties in metaphor comprehension in people with dyslexia that have been detected in previous studies might depend on meaning construction in context rather than online semantic processing.

Synergistic Interventions for Silencing Oppositional Defiant Disorder and Dyslexia in a Child With Attention-Deficit/Hyperactivity Disorder: A Case Report From Albania.

To the best of the authors' knowledge, this article is the first of its kind in Albania and neighboring countries to investigate the transformative synergistic intervention approach through cognitive behavioral therapy, parent-child interaction therapy (PCIT), and heavy metal detoxification on a child with attention-deficit/hyperactivity disorder (ADHD) and comorbid oppositional defiant disorder (ODD) and dyslexia. The limited mental health awareness in Albania, particularly regarding PCIT and similar treatments, highlights the importance of the applicability and adaptability of such interventions. This study suggests that the rapid management of comorbidities in ADHD, such as ODD and dyslexia, is better achieved by a combined intervention approach and by investigating the biological aspects. Further research with a large sample size is needed to assess the long-term sustainability and scalability of such an approach.

White matter microstructural plasticity associated with educational intervention in reading disability.

Children's reading progress typically slows during extended breaks in formal education, such as summer vacations. This stagnation can be especially concerning for children with reading difficulties or disabilities, such as dyslexia, because of the potential to exacerbate the skills gap between them and their peers. Reading interventions can prevent skill loss and even lead to appreciable gains in reading ability during the summer. Longitudinal studies relating intervention response to brain changes can reveal educationally relevant insights into rapid learning-driven brain plasticity. The current work focused on reading outcomes and white matter connections, which enable communication among the brain regions required for proficient reading. We collected reading scores and diffusion-weighted images at the beginning and end of summer for 41 children with reading difficulties who had completed either 1st or 2nd grade. Children were randomly assigned to either receive an intensive reading intervention (n = 26; Seeing Stars from Lindamood-Bell which emphasizes orthographic fluency) or be deferred to a wait-list group (n = 15), enabling us to analyze how white matter properties varied across a wide spectrum of skill development and regression trajectories. On average, the intervention group had larger gains in reading compared to the non-intervention group, who declined in reading scores. Improvements on a proximal measure of orthographic processing (but not other more distal reading measures) were associated with decreases in mean diffusivity within core reading brain circuitry (left arcuate fasciculus and left inferior longitudinal fasciculus) and increases in fractional anisotropy in the left corticospinal tract. Our findings suggest that responses to intensive reading instruction are related predominantly to white matter plasticity in tracts most associated with reading.

Assessing students with dyslexia and other reading difficulties through multiple diagnostic assessments.

This article aims to assist practitioners in understanding dyslexia and other reading difficulties and assessing students' learning needs. We describe the essential components of language and literacy, universal screening, diagnostic assessments, curriculum-based measurement and eligibility determination. We then introduce four diagnostic assessments as examples, including norm-referenced assessments (i.e. the Comprehensive Test of Phonological Processing second edition and the Woodcock-Johnson IV Tests of Achievement) and criterion-referenced assessments (i.e. the Gallistel-Ellis Test of Coding Skills and the Dynamic Indicators of Basic Early Literacy Skills). Finally, We use a makeup case as a concrete example to illustrate how multiple diagnostic assessments are recorded and how the results can be used to inform intervention and eligibility for special education services.

Alterations in neural activation in the ventral frontoparietal network during complex magnocellular stimuli in developmental dyslexia associated with READ1 deletion.

BACKGROUND: An intronic deletion within intron 2 of the DCDC2 gene encompassing the entire READ1 (hereafter, READ1d) has been associated in both children with developmental dyslexia (DD) and typical readers (TRs), with interindividual variation in reading performance and motion perception as well as with structural and functional brain alterations. Visual motion perception -- specifically processed by the magnocellular (M) stream -- has been reported to be a solid and reliable endophenotype of DD. Hence, we predicted that READ1d should affect neural activations in brain regions sensitive to M stream demands as reading proficiency changes. METHODS: We investigated neural activations during two M-eliciting fMRI visual tasks (full-field sinusoidal gratings controlled for spatial and temporal frequencies and luminance contrast, and sensitivity to motion coherence at 6%, 15% and 40% dot coherence levels) in four subject groups: children with DD with/without READ1d, and TRs with/without READ1d. RESULTS: At the Bonferroni-corrected level of significance, reading skills showed a significant effect in the right polar frontal cortex during the full-field sinusoidal gratings-M task. Regardless of the presence/absence of the READ1d, subjects with poor reading proficiency showed hyperactivation in this region of interest (ROI) compared to subjects with better reading scores. Moreover, a significant interaction was found between READ1d and reading performance in the left frontal opercular area 4 during the 15% coherent motion sensitivity task. Among subjects with poor reading performance, neural activation in this ROI during this specific task was higher for subjects without READ1d than for READ1d carriers. The difference vanished as reading skills increased. CONCLUSIONS: Our findings showed a READ1d-moderated genetic vulnerability to alterations in neural activation in the ventral attentive and salient networks during the processing of relevant stimuli in subjects with poor reading proficiency.

Review of the Brain's Behaviour after Injury and Disease for Its Application in an Agent-Based Model (ABM).

The brain is the most complex organ in the human body and, as such, its study entails great challenges (methodological, theoretical, etc.). Nonetheless, there is a remarkable amount of studies about the consequences of pathological conditions on its development and functioning. This bibliographic review aims to cover mostly findings related to changes in the physical distribution of neurons and their connections-the connectome-both structural and functional, as well as their modelling approaches. It does not intend to offer an extensive description of all conditions affecting the brain; rather, it presents the most common ones. Thus, here, we highlight the need for accurate brain modelling that can subsequently be used to understand brain function and be applied to diagnose, track, and simulate treatments for the most prevalent pathologies affecting the brain.

Atypical low-frequency cortical encoding of speech identifies children with developmental dyslexia.

Slow cortical oscillations play a crucial role in processing the speech amplitude envelope, which is perceived atypically by children with developmental dyslexia. Here we use electroencephalography (EEG) recorded during natural speech listening to identify neural processing patterns involving slow oscillations that may characterize children with dyslexia. In a story listening paradigm, we find that atypical power dynamics and phase-amplitude coupling between delta and theta oscillations characterize dyslexic versus other child control groups (typically-developing controls, other language disorder controls). We further isolate EEG common spatial patterns (CSP) during speech listening across delta and theta oscillations that identify dyslexic children. A linear classifier using four delta-band CSP variables predicted dyslexia status (0.77 AUC). Crucially, these spatial patterns also identified children with dyslexia when applied to EEG measured during a rhythmic syllable processing task. This transfer effect (i.e., the ability to use neural features derived from a story listening task as input features to a classifier based on a rhythmic syllable task) is consistent with a core developmental deficit in neural processing of speech rhythm. The findings are suggestive of distinct atypical neurocognitive speech encoding mechanisms underlying dyslexia, which could be targeted by novel interventions.

Early Detection of 5 Neurodevelopmental Disorders of Children and Prevention of Postnatal Depression With a Mobile Health App: Observational Cross-Sectional Study.

BACKGROUND: Delay in the diagnosis of neurodevelopmental disorders (NDDs) in toddlers and postnatal depression (PND) is a major public health issue. In both cases, early intervention is crucial but too rarely implemented in practice. OBJECTIVE: Our goal was to determine if a dedicated mobile app can improve screening of 5 NDDs (autism spectrum disorder [ASD], language delay, dyspraxia, dyslexia, and attention-deficit/hyperactivity disorder [ADHD]) and reduce PND incidence. METHODS: We performed an observational, cross-sectional, data-based study in a population of young parents in France with at least 1 child aged <10 years at the time of inclusion and regularly using Malo, an "all-in-one" multidomain digital health record electronic patient-reported outcome (PRO) app for smartphones. We included the first 50,000 users matching the criteria and agreeing to participate between May 1, 2022, and February 8, 2024. Parents received periodic questionnaires assessing skills in neurodevelopment domains via the app. Mothers accessed a support program to prevent PND and were requested to answer regular PND questionnaires. When any PROs matched predefined criteria, an in-app recommendation was sent to book an appointment with a family physician or pediatrician. The main outcomes were the median age of the infant at the time of notification for possible NDD and the incidence of PND detection after childbirth. One secondary outcome was the relevance of the NDD notification by consultation as assessed by health professionals. RESULTS: Among 55,618 children median age 4 months (IQR 9), 439 (0.8%) had at least 1 disorder for which consultation was critically necessary. The median ages of notification for probable ASD, language delay, dyspraxia, dyslexia, and ADHD were 32.5 (IQR 12.8), 16 (IQR 13), 36 (IQR 22.5), 80 (IQR 5), and 61 (IQR 15.5) months, respectively. The rate of probable ADHD, ASD, dyslexia, language delay, and dyspraxia in the population of children of the age included between the detection limits of each alert was 1.48%, 0.21%, 1.52%, 0.91%, and 0.37%, respectively. Sensitivity of alert notifications for suspected NDDs as assessed by the physicians was 78.6% and specificity was 98.2%. Among 8243 mothers who completed a PND questionnaire, highly probable PND was detected in 938 (11.4%), corresponding to a reduction of -31% versus our previous study without a support program. Suspected PND was detected a median 96 days (IQR 86) after childbirth. Among 130 users who filled in the satisfaction survey, 99.2% (129/130) found the app easy to use and 70% (91/130) reported that the app improved follow-up of their child. The app was rated 4.8/5 on Apple's App Store. CONCLUSIONS: Algorithm-based early alerts suggesting NDDs were highly specific with good sensitivity as assessed by real-life practitioners. Early detection of 5 NDDs and PNDs was efficient and led to a possible 31% reduction in PND incidence. TRIAL REGISTRATION: ClinicalTrials.gov NCT06301087; https://www.clinicaltrials.gov/study/NCT06301087.

Understanding mental health in developmental dyslexia through a neurodiversity lens: The mediating effect of school-connectedness on anxiety, depression and conduct problems.

Dyslexia, a neurocognitive difference characterised by poor word-reading, is associated with elevated risk for internalising (e.g., anxiety) and externalising (e.g., aggression) mental health concerns, the reasons are largely unknown. We took a neurodiversity perspective and explored whether school-connectedness mediated these associations. A total of 283 primary school children (87 with dyslexia) and their caregivers (95.4% mothers) completed a battery of well-validated connectedness and mental health measures. Two mediation models (one for child-report and one for caregiver-report) tested direct and indirect effects of dyslexia on anxiety, depression and conduct problems via several domains of school-connectedness. After controlling for gender and neurodevelopmental conditions other than dyslexia, there were no direct effects of dyslexia on child- or caregiver-reported internalising symptoms or child-reported conduct problems. Dyslexia was associated with child and caregiver reported anxiety, depression and conduct problems via low levels of school (but not teacher, friend or peer) connectedness. Findings highlight school-connectedness as an important intervention target for the mental health of children with dyslexia. Future research is needed to test associations between dyslexia, school-connectedness and mental health over time.

Eyes on CVI: Eye movements unveil distinct visual search patterns in Cerebral Visual Impairment compared to ADHD, dyslexia, and neurotypical children.

Visual search problems are often reported in children with Cerebral Visual Impairment (CVI). To tackle the clinical challenge of objectively differentiating CVI from other neurodevelopmental disorders, we developed a novel test battery. Visual search tasks were coupled with verbal and gaze-based measurements. Two search tasks were performed by children with CVI (n: 22; mean age (SD): 9.63 (.46) years) ADHD (n: 32; mean age (SD): 10.51 (.25) years), dyslexia (n: 28; mean age (SD): 10.29 (.20) years) and neurotypical development (n: 44; mean age (SD): 9.30 (.30) years). Children with CVI had more impaired search performance compared to all other groups, especially in crowded and unstructured displays and even when they had normal visual acuity. In-depth gaze-based analyses revealed that this group searched in overall larger areas and needed more time to recognize a target, particularly after their initial fixation on the target. Our gaze-based approach to visual search offers new insights into the distinct search patterns and behaviours of children with CVI. Their tendency to overlook targets whilst fixating on it, point towards higher-order visual function (HOVF) deficits. The novel method is feasible, valid, and promising for clinical differential-diagnostic evaluation between CVI, ADHD and dyslexia, and for informing individualized training.

Shared and task-specific brain functional differences across multiple tasks in children with developmental dyslexia.

Different tasks have been used in examining the neural functional differences associated with developmental dyslexia (DD), and consequently, different findings have been reported. However, very few studies have systematically compared multiple tasks in understanding what specific task differences each brain region is associated with. In this study, we employed an auditory rhyming task, a visual rhyming task, and a visual spelling task, in order to investigate shared and task-specific neural differences in Chinese children with DD. First, we found that children with DD had reduced activation in the opercular part of the left inferior frontal gyrus (IFG) only in the two rhyming tasks, suggesting impaired phonological analysis. Children with DD showed functional differences in the right lingual gyrus/inferior occipital gyrus only in the two visual tasks, suggesting deficiency in their visuo-orthographic processing. Moreover, children with DD showed reduced activation in the left dorsal inferior frontal gyrus and increased activation in the right precentral gyrus across all of the three tasks, suggesting neural signatures of DD in Chinese. In summary, our study successfully separated brain regions associated with differences in orthographic processing, phonological processing, and general lexical processing in DD. It advances our understanding about the neural mechanisms of DD.

Dyslexia in the twenty-first century: a commentary on the IDA definition of dyslexia.

In offering a commentary upon the IDA definition, we address its main components in turn. While each is technically accurate, we argue that, when taken together, the definition, or more accurately, the use to which it is often put, becomes problematic. We outline different current conceptions of dyslexia and conclude that the operationalisation of the definition for diagnostic purposes often results in scientifically questionable diagnoses and inadvertently leads to significant educational inequity. We propose a simpler definition that describes the primary difficulty, avoids reference to causal explanation, unexpectedness, and secondary outcomes, and redirects practitioner and policymaker focus to the importance of addressing and meeting the needs of all struggling readers.

The gift of dyslexia: what is the harm in it?

Dyslexia, characterized by word reading and spelling deficits, has historically been viewed through a medical model of disability. However, a countermovement has emerged, emphasizing the strengths and abilities of neurodiverse individuals, including those with dyslexia. The concept of neurodiversity, which was initially introduced to help inform understanding of a mild form of autism, has expanded to include dyslexia. The expansion has occurred alongside a similar portrayal of dyslexia as an advantage that comes with specific gifts, creating a positive stereotype. While intended to empower individuals with dyslexia, the translation of the concept of neurodiversity to dyslexia in this way can inadvertently stigmatize and isolate those who do not fit this positive stereotype of dyslexia. This review, following a perspective review article format, synthesizes existing literature on the purported gifts of dyslexia and the implications of both negative and positive stereotypes on the well-being of individuals with dyslexia. The findings of this review underscore the importance of dispelling myths about dyslexia and advocating against the use of stereotypes, both negative and positive, in portraying dyslexia. Doing so will help remove the harmful effects of stigmatization, stereotype threat, and the potential of a fixed mindset inherent to being stereotyped.

Alouette-R normative data for French-speaking school-aged children living in Quebec.

BACKGROUND: The Alouette-R (2005) by Lefavrais is one of the most widely used tools to assess reading skills in French. However, this instrument does not have normative data specific to the French-speaking population of Quebec, Canada. AIMS: The validity of an assessment being strongly compromised when using inappropriate norms, the first objective of this study was to establish local norms for the Alouette-R. The second objective was to provide sensitivity and specificity data for each Alouette-R measure in the French-speaking Quebec population. The third objective was to compare Quebec and French normative data and their sensitivity to better understand the applicability and effectiveness of the Alouette-R test at the regional level. METHODS & PROCEDURES: A total of 347 fluent readers and 48 children with dyslexia from 3rd to 6th grades were recruited from different regions in Quebec. Participants had to read aloud the 265-word text of the Alouette-R in a maximum of 3 min. OUTCOMES & RESULTS: Norms (means, standard deviations and percentiles) by school grades were created for each test measure: reading time, number of words read, number of errors, number of words correctly read, reading accuracy index and reading fluency index. The sensitivity (i.e., the ability to correctly identify children with dyslexia) and specificity (i.e., the ability to correctly identify children without dyslexia) of these measurements were also documented. The norms and their sensitivity were then compared with those of the original French study by Lefavrais in 2005. CONCLUSIONS & IMPLICATIONS: The presence of differences between European and Quebec norms supports the importance of using local norms when assessing language skills. The reading accuracy and fluency indexes are the measurements that best discriminated children with dyslexia from those without a reading disorder in our study. This study will allow clinicians working in Quebec to have a better interpretation of the Alouette-R measurements and ultimately avoid erroneous conclusions resulting from the use of foreign normative data. WHAT THIS PAPER ADDS: What is already known on this subject The Alouette-R is a reading test validated and standardized in France to screen for dyslexia in children. The validity of existing norms with the Quebec population in Canada is questionable due to socio-linguistic differences with the population of France. What this study adds to existing knowledge This study provides for the first time normative and sensitivity/specificity data of the Alouette-R for French-speaking school-aged children living in Quebec. Differences were noted with the normative data from France, which supports the importance of using local normative data when administering reading tests in Quebec. What are the potential or actual clinical implications of this work? When administering the Alouette-R, clinicians in Quebec will now be able to use normative data adapted to the local population, which will limit erroneous conclusions resulting from the use of foreign normative data. In addition, the sensitivity and specificity values reported in the article will allow these clinicians to better interpret their results when screening for a developmental reading disorder.

Dyslexics Exhibit an Orthographic, Not a Phonological Deficit in Lexical Decision.

Dyslexia is theorized to be caused by phonological deficits, visuo-attentional deficits, or some combination of the two. The present study contrasted phonological and visuo-attentional theories of dyslexia using a lexical decision task administered to adult participants with and without dyslexia. Homophone and pseudo-homophone stimuli were included to explore whether the two groups differed in their reliance on phonological encoding. Transposed-letter stimuli, including both TL neighbors and TL non-words, measured potential orthographic impairment predicted by visuo-attentional deficit theories. The findings revealed no significant difference in response time or accuracy between the groups for the homophone and pseudo-homophone stimuli. However, dyslexics were significantly slower and less accurate in their responses to the TL stimuli than controls. Thus, dyslexics presented deficits consistent with visuo-attentional theories, but not with the phonological deficit theory.

Mind, brain and education-Neuromechanisms during child development.

BACKGROUND AND AIMS: Educational neuroscience has emerged as an interdisciplinary field aimed at elucidating the neurobiological underpinnings of learning and educational outcomes. By synthesizing findings from diverse research endeavours, this Editorial aims to delineate the intricate interplay between neural processes and educational experiences, shedding light on the factors that shape cognitive development and learning trajectories in children. RESULTS: This Editorial highlights significant advancements, spanning investigations into neural mechanisms, cognitive development and educational interventions on the basis of four exemplary topics and their effects on academic learning and achievement: student's academic self-concept, (cyber-)bullying, reading skills/dyslexia and a growth mindset intervention. Summaries of the four empirical contributions in this special issue are presented and discussed in relation to how they provide insight into the dynamic interplay between neural mechanisms and environmental influences, underscoring the role of early experiences in sculpting brain development and shaping educational outcomes. Furthermore, the integration of neuroscientific techniques (e.g., fMRI, eye-tracking) with educational research methodologies has provided novel insights into the neural correlates of learning processes, executive functions and socio-emotional development during childhood. CONCLUSIONS: In conclusion, the pivotal role of Educational Neuroscience in bridging the gap between neuroscience and education is highlighted. By elucidating the neurobiological foundations of learning, this interdisciplinary field offers valuable insights for informing evidence-based educational practices and interventions tailored to individual learning profiles. Moving forward, continued collaboration between researchers, educators and policymakers is essential to harnessing the full potential of Educational Neuroscience in promoting cognitive growth and academic success across diverse learner populations.

A transdiagnostic approach to neurodiversity in a representative population sample: The N+ 4 model.

Background: The concept of neurodiversity draws upon scientific research, and lessons from practice and lived experience to suggest new ways of thinking about neurodevelopmental conditions. Among the formative observations are that characteristics associated with neurodevelopmental conditions are part of a "broader phenotype" of variation across the whole population, and that there appear to be "transdiagnostic" similarities as well as differences in these characteristics. These observations raise important questions that have implications for understanding diversity in neurodevelopmental conditions and in neurocognitive phenotypes across the whole population. Method: The present work examines broader phenotypes using seven widely used self-report assessments of traits associated with autism, ADHD, dyslexia, Developmental Coordination Disorder/dyspraxia, tic disorders/Tourette's, cortical hyperexcitability associated with subclinical epilepsy, and sensory sensitivities. A representative sample of 995 adults (aged 17-77) in the UK completed self-report measures of neurodiversity, wellbeing, generalized anxiety, and depression, and cognitive abilities (nonverbal intelligence and executive functioning). Results: We used confirmatory factor analysis to test whether variation and covariation was better characterized (1) by traditional diagnostic labels, or (2) transdiagnostically according to similarities in functions, behaviours, or phenomena. Results indicated that neurodiversity characteristics were best explained using a bifactor model with one general "N" factor and four condition-specific factors. Conclusion: This was the largest examination to date of the factor structure of broader phenotypes relevant to neurodevelopmental conditions. It provides critical benchmark data, and a framework approach for asking systematic questions about the structure of neurocognitive diversities seen in the whole population and in people with one or more diagnoses.