White matter integrity and math performance in pediatric multiple sclerosis: a diffusion tensor imaging study

Multimodal neuroimaging correlates of physical-cognitive covariation in Chilean adolescents. The Cogni-Action Project

Health-related behaviours have been related to brain structural features. In developing settings, such as Latin America, high social inequality has been inversely associated with several health-related behaviours affecting brain development. Understanding the relationship between health behaviours and brain structure in such settings is particularly important during adolescence when critical habits are acquired and ingrained. In this cross-sectional study, we carry out a multimodal analysis identifying a brain region associated with health-related behaviours (i.e., adiposity, fitness, sleep problems and others) and cognitive/academic performance, independent of socioeconomic status in a large sample of Chilean adolescents. Our findings suggest that the relationship between health behaviours and cognitive/academic performance involves a particular brain phenotype that could play a mediator role. These findings fill a significant gap in the literature, which has largely focused on developed countries and raise the possibility of promoting healthy behaviours in adolescence as a means to influence brain structure and thereby cognitive/academic achievement, independently of socioeconomic factors. By highlighting the potential impact on brain structure and cognitive/academic achievement, policymakers could design interventions that are more effective in reducing health disparities in developing countries.

Changes in the superior longitudinal fasciculus and anterior thalamic radiation in the left brain are associated with developmental dyscalculia

Developmental dyscalculia is a neurodevelopmental disorder specific to arithmetic learning even with normal intelligence and age-appropriate education. Difficulties often persist from childhood through adulthood lowering the individual's quality of life. However, the neural correlates of developmental dyscalculia are poorly understood. This study aimed to identify brain structural connectivity alterations in developmental dyscalculia. All participants were recruited from a large scale, non-referred population sample in a longitudinal design. We studied 10 children with developmental dyscalculia (11.3 ± 0.7 years) and 16 typically developing peers (11.2 ± 0.6 years) using diffusion-weighted magnetic resonance imaging. We assessed white matter microstructure with tract-based spatial statistics in regions-of-interest tracts that had previously been related to math ability in children. Then we used global probabilistic tractography for the first time to measure and compare tract length between developmental dyscalculia and typically developing groups. The high angular resolution diffusion-weighted magnetic resonance imaging and crossing-fiber probabilistic tractography allowed us to evaluate the length of the pathways compared to previous studies. The major findings of our study were reduced white matter coherence and shorter tract length of the left superior longitudinal/arcuate fasciculus and left anterior thalamic radiation in the developmental dyscalculia group. Furthermore, the lower white matter coherence and shorter pathways tended to be associated with the lower math performance. These results from the regional analyses indicate that learning, memory and language-related pathways in the left hemisphere might be related to developmental dyscalculia in children.

Symptom Interconnectivity in Multiple Sclerosis: A Narrative Review of Potential Underlying Biological Disease Processes

Introduction

Fatigue, cognitive impairment, depression, and pain are highly prevalent symptoms in multiple sclerosis (MS). These often co-occur and may be explained by a common etiology. By reviewing existing literature, we aimed to identify potential underlying biological processes implicated in the interconnectivity between these symptoms.

Methods

A literature search was conducted to identify articles reporting research into the biological mechanisms responsible for the manifestation of fatigue, cognitive impairment, depression, and pain in MS. PubMed was used to search for articles published from July 2011 to July 2021. We reviewed and assessed findings from the literature to identify biological processes common to the symptoms of interest.

Results

Of 693 articles identified from the search, 252 were selected following screening of titles and abstracts and assessing reference lists of review articles. Four biological processes linked with two or more of the symptoms of interest were frequently identified from the literature: (1) direct neuroanatomical changes to brain regions linked with symptoms of interest (e.g., thalamic injury associated with cognitive impairment, fatigue, and depression), (2) pro-inflammatory cytokines associated with so-called ‘sickness behavior,’ including manifestation of fatigue, transient cognitive impairment, depression, and pain, (3) dysregulation of monoaminergic pathways leading to depressive symptoms and fatigue, and (4) hyperactivity of the hypothalamic–pituitary-adrenal (HPA) axis as a result of pro-inflammatory cytokines promoting the release of brain noradrenaline, serotonin, and tryptophan, which is associated with symptoms of depression and cognitive impairment.

Conclusion

The co-occurrence of fatigue, cognitive impairment, depression, and pain in MS appears to be associated with a common set of etiological factors, namely neuroanatomical changes, pro-inflammatory cytokines, dysregulation of monoaminergic pathways, and a hyperactive HPA axis. This association of symptoms and biological processes has important implications for disease management strategies and, eventually, could help find a common therapeutic pathway that will impact both inflammation and neuroprotection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-022-00368-2.

Patterns of white and gray structural abnormality associated with paediatric demyelinating disorders

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A multi-modal approach was used to evaluate the visual pathway from anterior (retina) to posterior (visual cortex) in both paediatric MOGAD and MS patients.

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MS patients exhibited more widespread white matter abnormalities; MOGAD patients exhibited white matter changes primarily within the optic radiation.

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The pattern of cortical thinning differed in MS and MOGAD patients.

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Reduced RNFLT was associated with lower axonal density in MOGAD and tortuosity in MS.

The impact of multiple sclerosis (MS) and myelin oligodendrocyte glycoprotein (MOG) - associated disorders (MOGAD) on brain structure in youth remains poorly understood. Reductions in cortical mantle thickness on structural MRI and abnormal diffusion-based white matter metrics (e.g., diffusion tensor parameters) have been well documented in MS but not in MOGAD. Characterizing structural abnormalities found in children with these disorders can help clarify the differences and similarities in their impact on neuroanatomy. Importantly, while MS and MOGAD affect the entire CNS, the visual pathway is of particular interest in both groups, as most patients have evidence for clinical or subclinical involvement of the anterior visual pathway. Thus, the visual pathway is of key interest in analyses of structural abnormalities in these disorders and may distinguish MOGAD from MS patients.

In this study we collected MRI data on 18 MS patients, 14 MOGAD patients and 26 age- and sex-matched typically developing children (TDC). Full-brain group differences in fixel diffusion measures (fibre-bundle populations) and cortical thickness measures were tested using age and sex as covariates. Visual pathway analysis was performed by extracting mean diffusion measures within lesion free optic radiations, cortical thickness within the visual cortex, and retinal nerve fibre layer (RNFL) and ganglion cell layer thickness measures from optical coherence tomography (OCT). Fixel based analysis (FBA) revealed MS patients have widespread abnormal white matter within the corticospinal tract, inferior longitudinal fasciculus, and optic radiations, while within MOGAD patients, non-lesional impact on white matter was found primarily in the right optic radiation. Cortical thickness measures were reduced predominately in the temporal and parietal lobes in MS patients and in frontal, cingulate and visual cortices in MOGAD patients. Additionally, our findings of associations between reduced RNFLT and axonal density in MOGAD and TORT in MS patients in the optic radiations imply widespread axonal and myelin damage in the visual pathway, respectively. Overall, our approach of combining FBA, cortical thickness and OCT measures has helped evaluate similarities and differences in brain structure in MS and MOGAD patients in comparison to TDC.

Disrupted cognitive development following pediatric acquired demyelinating syndromes: a longitudinal study

Long-term cognitive deficits have been observed in some children who experience an acquired demyelinating syndrome (ADS). We examined changes in cognitive functioning over the first two years following incident ADS andtested whether normalized brain and thalamic volume accounted for decline over time. Twenty-five youth (mean age 12.8 years) with ADS, 9 of whom were diagnosed with multiple sclerosis (MS) and 16 of whom experienced monophasic ADS (monoADS), underwent two neuropsychological evaluationsand MRI scans at approximately6- and 24-months post ADS-onset. We examined changes in cognitive outcomes over time and between patient groups. Generalized linear mixed-effect regression models were used to examine the association of normalized brain and thalamic volumesbetween the two timepointswith cognitive z-scores. Cognitive performance was within the age-expected range for both groups and remained stable over time on 15 measures. In the combined sample of monoADS and MS patients, declines (p < .05) were noted on the Symbol Digit Modalities Test (SDMT), the Auditory Working Memory (AWM), and the WJ-III Visual Matching (VisMat)tests, but did not survive FDR correction. Clinically significant declines, as measured by the Reliable Change Index, were observed on the SDMT,AWM, and VisMattests by 19, 42, and 32%, respectively. Lower normalized brain volume at 6-months predicted a negative change in SDMT (B = 0.45, 95%CI: 0.07,0.83) and AWM (B = 0.30, 95%CI: 0.13, 0.47). Chronicity of demyelination is not required for cognitive decline nor for reduced brain volume, suggesting that even a single demyelinating event may negatively impact cognitive potential in children.

Association of Age at Onset With Gray Matter Volume and White Matter Microstructural Abnormalities in People With Multiple Sclerosis

BACKGROUND AND OBJECTIVES

To investigate whether age at onset influences brain gray matter volume (GMV) and white matter (WM) microstructural abnormalities in adult patients with multiple sclerosis (MS), given its influence on clinical phenotype and disease course.

METHODS

In this hypothesis-driven cross-sectional study, we enrolled 67 patients with pediatric-onset MS (POMS) and 143 sex- and disease duration (DD)-matched randomly selected patients with adult-onset MS (AOMS), together with 208 healthy controls. All participants underwent neurologic evaluation and 3T MRI acquisition. MRI variables were standardized based on healthy controls, to remove effects of age and sex. Associations with DD in patients with POMS and patients with AOMS were studied with linear models. Time to reach clinical and MRI milestones was assessed with product-limit approach.

RESULTS

At DD 1 year, GMV and WM fractional anisotropy (FA) were abnormal in AOMS but not in POMS. Significant interaction of age at onset (POMS vs AOMS) into the association with DD was found for GMV and WM FA. The crossing point of regression lines in POMS and AOMS was at 20 years of DD for GMV and 14 for WM FA. For POMS and AOMS, median DD was 29 and 19 years to reach Expanded Disability Status Scale score 3 (p < 0.001), 31 and 26 years to reach abnormal Paced Auditory Serial Addition Task, 3-second version (p = 0.01), 24 and 18 years to reach abnormal GMV (p = 0.04), and 19 and 17 years to reach abnormal WM FA (p = 0.36).

DISCUSSION

Younger patients are initially resilient to MS-related damage. Then, compensatory mechanisms start failing with loss of WM integrity, followed by GM atrophy and finally disability.

Cognitive Issues in Pediatric Multiple Sclerosis

Multiple sclerosis (MS) is one of the leading causes of disability in young adults. The onset of MS during developmental age makes pediatric patients particularly susceptible to cognitive impairment, resulting from both disease-related damage and failure of age-expected brain growth. Despite different test batteries and definitions, cognitive impairment has been consistently reported in approximately one-third of pediatric patients with MS. However, the lack of a uniform definition of cognitive impairment and the adoption of different test batteries have led to divergent results in terms of cognitive domains more frequently affected across the cohorts explored. This heterogeneity has hampered large international collaborative studies. Moreover, research aimed at the identification of risk factors (e.g., demographic, clinical, and radiological features) or protective factors (e.g., cognitive reserve, leisure activities) for cognitive decline is still scanty. Mood disorders, such as depression and anxiety, can be detected in these patients alongside cognitive decline or in isolation, and can negatively affect quality of life scores as well as academic performances. By using MRI, cognitive impairment was attributed to damage to specific brain compartments as well as to abnormal network activation patterns. However, multimodal MRI studies are still needed in order to assess the contribution of each MRI metric to cognitive impairment. Importantly, longitudinal studies have recently demonstrated failure of age-expected brain growth and of white matter (WM) and gray matter (GM) maturation plays a relevant role in determining cognitive dysfunction, in addition to MS-related direct damage. Whether these growth retardations might result in specific cognitive profiles according to the age at disease onset has not been studied, yet. A better characterization of cognitive profiles in pediatric MS patients, as well as the definition of neuroanatomical substrates of cognitive impairment and their longitudinal evolution are needed to develop efficient therapeutic strategies against cognitive impairment in this patient population.

White matter plasticity and maturation in human cognition

White matter plasticity likely plays a critical role in supporting cognitive development. However, few studies have used the imaging methods specific to white matter tissue structure or experimental designs sensitive to change in white matter necessary to elucidate these relations. Here we briefly review novel imaging approaches that provide more specific information regarding white matter microstructure. Furthermore, we highlight recent studies that provide greater clarity regarding the relations between changes in white matter and cognition maturation in both healthy children and adolescents and those with white matter insult. Finally, we examine the hypothesis that white matter is linked to cognitive function via its impact on neural synchronization. We test this hypothesis in a population of children and adolescents with recurrent demyelinating syndromes. Specifically, we evaluate group differences in white matter microstructure within the optic radiation; and neural phase synchrony in visual cortex during a visual task between 25 patients and 28 typically developing age-matched controls. Children and adolescents with demyelinating syndromes show evidence of myelin and axonal compromise and this compromise predicts reduced phase synchrony during a visual task compared to typically developing controls. We investigate one plausible mechanism at play in this relationship using a computational model of gamma generation in early visual cortical areas. Overall, our findings show a fundamental connection between white matter microstructure and neural synchronization that may be critical for cognitive processing. In the future, longitudinal or interventional studies can build upon our knowledge of these exciting relations between white matter, neural communication, and cognition.

Enhanced Recruitment During Executive Control Processing in Cognitively Preserved Patients With Pediatric-Onset MS

OBJECTIVES

Youth and young adults with pediatric-onset multiple sclerosis (MS) are vulnerable to executive dysfunction; however, some patients do not demonstrate functional deficits despite showing abnormalities on structural magnetic resonance imaging (MRI). Cognitively intact adults with MS have shown enhanced activation patterns relative to healthy controls on working memory tasks. We aim to evaluate whether cognitively preserved pediatric-onset MS patients engage compensatory recruitment strategies to facilitate age-normative performance on a task of working memory.

METHODS

Twenty cognitively preserved patients (mean age=18.7±2.7 years; 15 female) and 20 age- and sex-matched controls (mean age=18.5±2.9 years; 15 female) underwent neuropsychological testing and 3.0 Tesla MRI, including structural and functional acquisitions. Patterns of activation during the Alphaspan task, a working memory paradigm with two levels of executive control demand, were examined via whole-brain and region of interest (ROI) analyses.

RESULTS

Across all participants, lower accuracy and greater activation of regions implicated in working memory were observed during the high demand condition. MS patients demonstrated 0.21 s longer response time than controls. ROI analyses revealed enhanced activation for pediatric-onset MS patients relative to controls in the right middle frontal, left paracingulate, right supramarginal, and left superior parietal gyri during the low executive demand condition, over and above differences in response time. MS patients also demonstrated heightened activation in the right supramarginal gyrus in the high executive demand condition.

CONCLUSIONS

Our findings suggest that pediatric-onset MS patients may engage compensatory recruitment strategies during working memory processing. (JINS, 2019, 25, 432-442).

Cognitive Functioning in Patients with Pediatric-Onset Multiple Sclerosis, an Updated Review and Future Focus

Pediatric-onset multiple sclerosis (POMS) is relatively rare, but as technology and neuroimaging advance, an increasing number of cases are identified, and our understanding of how multiple sclerosis (MS) impacts the developing brain improves. There are consistent findings in the literature highlighting the impact of MS and other demyelinating diseases on cognitive functioning and cognitive development. We also have a better understanding of how POMS impacts psychosocial functioning and functional outcomes in daily living. This paper hopes to review findings associated with cognitive and psychosocial functioning in patients with POMS, as well as explore more recent advances in the field and how they relate to cognitive and psychosocial outcomes. We also discuss the ongoing need for future studies with a focus on better understanding deficits and disease correlates, but also preventative measures and potential rehabilitation.

Pediatric multiple sclerosis and fulminant disease course: Features and approaches to treatment - A case report and review of the literature

Multiple sclerosis (MS) is the autoimmune, neurodegenerative disease of the central nervous system (CNS). Typically, it affects the young adult population, however, up to 10% of the cases, it can develop in childhood. Atypical manifestations, such as the tumefactive variant (tMS) or acute disseminated encephalomyelitis (ADEM), especially coupled with fulminant disease course, are even more rare and pose a considerable differential diagnostic and therapeutic challenge. Recently, the therapeutic strategy on the use of disease modifying therapies (DMTs) in MS has shifted to the direction of a more individualized approach, that takes the personal differences heavily into account, in particular regard to the activity and prognosis of the disease. Despite this change has only been applied to adults yet, it is plausible to predict, that it will soon be applied to pediatric patients as well, particularly, as several randomized studies are under way concerning DMTs in pediatric populations. To our best knowledge, we are the first to report a successful natalizumab treatment of pediatric fulminant tMS, in case of a 13.5 years old girl. We feel that this report demonstrates the need of early and adequate treatment in such an aggressive case, because it can reverse the course of a possibly fatal disease.

Pediatric Multiple Sclerosis: Distinguishing Clinical and MR Imaging Features

This article presents an overview of evolving diagnostic criteria of pediatric multiple sclerosis and related disorders, emphasizing distinguishing clinical and neuroimaging features that should be considered for differential diagnosis in childhood and adolescence. New data on the integrity of brain tissue in children with MS provided by advanced MR imaging techniques are addressed as well.

Arithmetic in the developing brain: A review of brain imaging studies

Brain imaging studies on academic achievement offer an exciting window on experience-dependent cortical plasticity, as they allow us to understand how developing brains change when children acquire culturally transmitted skills. This contribution focuses on the learning of arithmetic, which is quintessential to mathematical development. The nascent body of brain imaging studies reveals that arithmetic recruits a large set of interconnected areas, including prefrontal, posterior parietal, occipito-temporal and hippocampal areas. This network undergoes developmental changes in its function, connectivity and structure, which are not yet fully understood. This network only partially overlaps with what has been found in adults, and clear differences are observed in the recruitment of the hippocampus, which are related to the development of arithmetic fact retrieval. Despite these emerging trends, the literature remains scattered, particularly in the context of atypical development. Acknowledging the distributed nature of the arithmetic network, future studies should focus on connectivity and analytic approaches that investigate patterns of brain activity, coupled with a careful design of the arithmetic tasks and assessments of arithmetic strategies. Such studies will produce a more comprehensive understanding of how the arithmetical brain unfolds, how it changes over time, and how it is impaired in atypical development.

Cognitive deficits including executive functioning in relation to clinical parameters in paediatric MS patients

Background

A number of studies have investigated cognitive impairment in paediatric patients with multiple sclerosis (MS) but deficits regarding executive functions have not been comprehensively assessed up to now. This study was meant to explore cognitive impairment in German paediatric MS patients with a focus on deficits in executive functions and relate these to clinical disease parameters.

Methods and findings

Forty paediatric MS patients, which presented at the German centre for MS in childhood and adolescence, were assessed for cognitive deficits applying a very comprehensive battery of cognitive tests including the Wechsler Intelligence scale and subtests of the D-KEFS for executive functions. The performance of MS patients was compared with a group of age and sex matched healthy controls using between-subjects ANOVAs. Paediatric MS patients performed worse in tests assessing verbal comprehension and fluency, processing speed, memory, calculation skills and other executive functions. Arranged by the cognitive domain, group differences were most pronounced regarding verbal comprehension and fluency for the WISC subtests Comprehension (p = 0.000), Vocabulary (p = 0.003) and Information (p = 0.005); regarding processing speed for the written SDMT (p = 0.001) and the WISC subtest Coding (p = 0.005); regarding memory for the VLMT training (p = 0.007) and the BASIC MLT pattern learning training (p = 0.009); regarding executive functions including working memory for the WISC subtest Arithmetics (p = 0.002), the D-KEFS Design Fluency (p = 0.003) and the Corsi block tapping backward task (p = 0.003). Fluid reasoning was largely intact. Relations of cognitive performance and clinical parameters were assessed in MS patients. Disease duration was associated with a reduced performance in tests belonging to the domains verbal comprehension and fluency (WISC Vocabulary: p = 0.034, WISC Information: p = 0.015) and fluid reasoning (WISC Picture Completion: p = 0.003) as well as the WISC Working Memory Index (p = 0.047). Patients with a disease onset between 11 and 14 years performed better in fluid reasoning (WISC matrix reasoning: p = 0.024) than patients with a disease onset at an age above 14. The number of relapses negatively influenced the visual spatial memory performance (BASIC MLT pattern learning training: p = 0.009).

Conclusions

The distribution of cognitive deficits in a representative group German of paediatric MS patients was similar to the pattern known from other European and North-American cohorts. Paediatric MS patients do have cognitive deficits in executive functions and key qualities necessary for successful school performance. Disease duration, age of onset and the number of relapses influence cognitive performance. Cognitive screenings should be implemented on a regular basis for paediatric MS patients, enabling early intervention.

Pediatric Multiple Sclerosis and Cognition: A Review of Clinical, Neuropsychologic, and Neuroradiologic Features

Multiple sclerosis (MS) is an inflammatory demyelinating and neurodegenerative disease. Although cognitive impairment has been well established in adult patients with MS, its occurrence in patients with pediatric-onset MS has recently been reported. In this review, I discuss the main features of cognitive impairment in pediatric MS as determined by long-term follow-up studies, neuropsychiatric test batteries, and the results of neuroradiological imaging studies that investigated the pathogenesis of pediatric MS. The most commonly affected cognitive domains in adults are attention, processing speed, and visuomotor skills; language and intelligence are also affected in pediatric MS. A young age at disease onset is the strongest risk factor for these impairments, which may be due to the effect of inflammatory demyelination and neurodegeneration on the developing central nervous system and neural networks in children. Cognitive impairment has long-term effects on patients' academic life and the quality of their social life. Therefore, all patients with pediatric MS should be screened and monitored for cognitive impairment. This review also highlights the need for neuropsychological test batteries that assess different cognitive domains in children and adolescents with multiple sclerosis and for cognitive rehabilitation programs to improve the quality of their academic and social life.

White matter changes in paediatric multiple sclerosis and monophasic demyelinating disorders

See Hacohen et al. (doi:10.1093/awx075) for a scientific commentary on this article. Most children who experience an acquired demyelinating syndrome of the central nervous system will have a monophasic disease course, with no further clinical or radiological symptoms. A subset will be diagnosed with multiple sclerosis, a life-long disorder. Using linear mixed effects models we examined longitudinal diffusion properties of normal-appearing white matter in 505 serial scans of 132 paediatric participants with acquired demyelinating syndromes followed for a median of 4.4 years, many from first clinical presentation, and 106 scans of 80 healthy paediatric participants. Fifty-three participants with demyelinating syndromes eventually received a diagnosis of paediatric-onset multiple sclerosis. Diffusion tensor imaging measures properties of water diffusion through tissue, which normally becomes increasingly restricted and anisotropic in the brain during childhood and adolescence, as fibre bundles develop and myelinate. In the healthy paediatric participants, our data demonstrate the expected trajectory of more restricted and anisotropic white matter diffusivity with increasing age. However, in participants with multiple sclerosis, fractional anisotropy decreased and mean diffusivity of non-lesional, normal-appearing white matter progressively increased after clinical presentation, suggesting not only a failure of age-expected white matter development but also a progressive loss of tissue integrity. Surprisingly, patients with monophasic disease failed to show age-expected changes in diffusion parameters in normal-appearing white matter, although they did not show progressive loss of integrity over time. Further analysis demonstrated that participants with monophasic disease experienced different post-onset trajectories in normal-appearing white matter depending on their presenting phenotype: those with acute disseminated encephalomyelitis demonstrated abnormal trajectories of diffusion parameters compared to healthy paediatric participants, as did patients with non-acute disseminated encephalomyelitis presentations associated with lesions in the brain at onset. Patients with monofocal syndromes such as optic neuritis, transverse myelitis, or isolated brainstem syndromes in whom multifocal brain lesions were absent, showed trajectories more closely approximating normal-appearing white matter development. Our findings also suggest the existence of sexual dimorphism in the effects of demyelinating syndromes on normal-appearing white matter development. Overall, we demonstrate failure of white matter maturational changes and progressive loss of white matter integrity in paediatric-onset multiple sclerosis, but also show that even a single demyelinating attack-when associated with white matter lesions in the brain-negatively impacts subsequent normal-appearing white matter development.

Bringing the HEET: The Argument for High-Efficacy Early Treatment for Pediatric-Onset Multiple Sclerosis

Pediatric-onset multiple sclerosis (POMS) is rarer than adult-onset disease, and represents a different diagnostic and treatment challenge to clinicians. We review POMS clinical and radiographic presentations, and explore important differences between POMS and adult-onset MS natural histories and long-term outcomes. Despite having more active disease, current treatment guidelines for patients with POMS endorse the off-label use of lower-efficacy disease-modifying therapies (DMTs) as first line. We review the available MS DMTs, their evidence for use in POMS, and the contrasting treatment strategies of high-efficacy early treatment and escalation therapy. We introduce a new treatment approach, the "high-efficacy early treatment", or HEET strategy, based on using directly observed, high-efficacy intravenously infused DMTs as first-line therapies. Like other proposed POMS treatment strategies, HEET will need to be prospectively studied, and all treatment decisions should be determined by an experienced neurologist, the patient, and his/her parents.

An update on multiple sclerosis in children: diagnosis, therapies, and prospects for the future

INTRODUCTION

Multiple sclerosis (MS), a chronic demyelinating disease of the central nervous system, is increasingly being recognized in children and adolescents. Pediatric MS follows a relapsing-remitting course at onset, with a risk for early cognitive impairment. Areas covered: In this review, we discuss the clinical features of acute demyelinating syndromes in children and risk factors that increase the likelihood of a diagnosis of MS. We also address the application of diagnostic criteria for MS in children, immunological features, therapeutic options and psychosocial considerations for children and adolescents with MS. Expert commentary: Collaborative multicenter clinical trials and research efforts are key to the advancement in understanding the pathophysiology and therapeutic strategies for multiple sclerosis across the lifespan.

Behavioral Symptoms in Pediatric Multiple Sclerosis: Relation to Fatigue and Cognitive Impairment

The emotional and behavioral problems associated with pediatric multiple sclerosis remain unclear. Participants with pediatric multiple sclerosis or clinically isolated syndrome (n = 140; ages 5-18 years) completed self- and parent ratings using the Behavioral Assessment System for Children, Second Edition, neurologic exam, the Fatigue Severity Scale, and neuropsychological assessment. Mean self- and parent-ratings on the Behavioral Assessment System for Children, Second Edition, were in the typical range across all scales. However, 33.1% indicated a clinically significant problem on a least 1 scale. Although the type of clinical problems varied across participants, attention problems, somatization, and anxiety were found to be most common. Disease features including duration, age of onset, neurologic disability, and fatigue did not distinguish those with and without clinical problems. However, cognitive functioning significantly predicted the presence of a clinical problem (P =02). Pediatric multiple sclerosis is associated with a range of nonspecific emotional and behavioral clinical problems, occurring more frequently in those patients with cognitive involvement.

Alterations in Functional and Structural Connectivity in Pediatric-Onset Multiple Sclerosis

Background

Reduced white matter (WM) integrity is a fundamental aspect of pediatric multiple sclerosis (MS), though relations to resting-state functional MRI (fMRI) connectivity remain unknown. The objective of this study was to relate diffusion-tensor imaging (DTI) measures of WM microstructural integrity to resting-state network (RSN) functional connectivity in pediatric-onset MS to test the hypothesis that abnormalities in RSN reflects changes in structural integrity.

Methods

This study enrolled 19 patients with pediatric-onset MS (mean age = 19, range 13–24 years, 14 female, mean disease duration = 65 months, mean age of disease onset = 13 years) and 16 age- and sex-matched healthy controls (HC). All subjects underwent 3.0T anatomical and functional MRI which included DTI and resting-state acquisitions. DTI processing was performed using Tract-Based Spatial Statistics (TBSS). RSNs were identified using Independent Components Analysis, and a dual regression technique was used to detect between-group differences in the functional connectivity of RSNs. Correlations were investigated between DTI measures and RSN connectivity.

Results

Lower fractional anisotropy (FA) was observed in the pediatric-onset MS group compared to HC group within the entire WM skeleton, and particularly the corpus callosum, posterior thalamic radiation, corona radiata and sagittal stratum (all p < .01, corrected). Relative to HCs, MS patients showed higher functional connectivity involving the anterior cingulate cortex and right precuneus of the default-mode network, as well as involving the anterior cingulate cortex and left middle frontal gyrus of the frontoparietal network (all p < .005 uncorrected, k≥30 voxels). Higher functional connectivity of the right precuneus within the default-mode network was associated with lower FA of the entire WM skeleton (r = -.525, p = .02), genu of the corpus callosum (r = -.553, p = .014), and left (r = -.467, p = .044) and right (r = -.615, p = .005) sagittal stratum.

Conclusions

Loss of WM microstructural integrity is associated with increased resting-state functional connectivity in pediatric MS, which may reflect a diffuse and potentially compensatory activation early in MS.

Systematic Review of Cognitive Dysfunction in Pediatric and Juvenile Multiple Sclerosis

BACKGROUND

Cognitive dysfunction is a common finding in individuals with multiple sclerosis at all ages. Cognitive impairment may drastically affect the life of younger patients with multiple sclerosis who are still undergoing education and schooling.

METHODS

We carried out a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations to assess the published data on multiple sclerosis and cognition in pediatric or juvenile patients. Only articles presenting original data on patients with multiple sclerosis diagnosed before age 18 years of age were included.

RESULTS

Thirty-two articles fulfilled the inclusion criteria for this systematic review. The conclusion from all articles was that cognitive dysfunction in multiple sclerosis starting before the age of 18 years is both significant and disruptive and must be routinely assessed. However, assessment methods were heterogeneous and often very expensive to perform, whereas proposals for treatment were virtually absent in the literature.

CONCLUSION

Cognitive dysfunction can be a significant symptom of multiple sclerosis of early onset, but its impact and management needs to be better assessed. A task force should be created to study and manage cognitive dysfunction in pediatric and juvenile multiple sclerosis.

Altered resting-state functional connectivity in cognitively preserved pediatric-onset MS patients and relationship to structural damage and cognitive performance

OBJECTIVE

To evaluate resting-state functional connectivity (FC) and relationship to brain volumes and cognition in a sample of cognitively preserved pediatric-onset multiple sclerosis (MS) patients.

METHODS

Sixteen cognitively intact pediatric-onset MS patients and 15 healthy age- and sex-matched controls underwent cognitive testing and 3T anatomical and functional MRI. Resting-state FC patterns were examined using region-of-interest-based timeseries correlations.

RESULTS

Compared to controls, pediatric-onset MS patients demonstrated higher FC of the precuneus, particularly with the anterior cingulate cortex (z=4.21, p<.001), frontal medial cortex (z=3.48, p<.001), and cerebellum (z=3.72, p<.001). Greater T2 lesion volume and lower normalized thalamic volume were associated with reduced FC of the thalamus, especially for FC with the right superior occipital region (t=-2.87, p=.0123 and t=2.27, p=.04 respectively). FC of the left frontal medial cortex was negatively correlated with composite cognitive z-score in the pediatric-onset MS group (p<.05).

CONCLUSIONS

Greater resting-state FC between posterior and anterior brain regions is present in pediatric-onset MS. With greater disease-related structural pathology, there is a disruption of thalamo-cortical FC. In the absence of actual cognitive impairment, heightened FC of the frontal medial cortex was associated with lower cognitive performance, suggesting that greater functional resources are recruited during resting-state in patients with reduced cognitive efficiency.

Diffusion tensor magnetic resonance imaging in very early onset pediatric multiple sclerosis

Objectives:

Active myelination during childhood may influence the impact of multiple sclerosis (MS) on brain structural integrity. We studied normal-appearing white matter (NAWM) in children with MS onset before age 12 years using diffusion tensor (DT) magnetic resonance imaging (MRI).

Methods:

DT MRI scans were obtained from 22 MS children with their first attack before age 12 years, and 31 healthy controls from two referral centers. Using probabilistic tractography, brain tissue integrity within interhemispheric, intrahemispheric, and projection tracts was compared between patients and site-matched controls. The impact of disease and age at MRI on tract NAWM fractional anisotropy (FA) and mean diffusivity (MD) values was evaluated using linear models.

Results:

Compared to controls, pediatric MS patients had reduced FA and increased MD of the bilateral superior longitudinal fasciculus and corpus callosum (CC), without center-by-group interaction. CC NAWM average FA was correlated with brain T2 lesion volume. In controls, the majority of the tracts analyzed showed a significant increase of FA and decrease of MD with age. Such a linear correlation was lost in patients.

Conclusions:

In very young pediatric MS patients, DT MRI abnormalities affect brain WM tracts differentially, and are only partially correlated with focal WM lesions. Impaired maturation of WM tracts with age may be an additional factor contributing to these findings.

A review on functional and structural brain connectivity in numerical cognition

Only recently has the complex anatomo-functional system underlying numerical cognition become accessible to evaluation in the living brain. We identified 27 studies investigating brain connectivity in numerical cognition. Despite considerable heterogeneity regarding methodological approaches, populations investigated, and assessment procedures implemented, the results provided largely converging evidence regarding the underlying brain connectivity involved in numerical cognition. Analyses of both functional/effective as well as structural connectivity have consistently corroborated the assumption that numerical cognition is subserved by a fronto-parietal network including (intra)parietal as well as (pre)frontal cortex sites. Evaluation of structural connectivity has indicated the involvement of fronto-parietal association fibers encompassing the superior longitudinal fasciculus dorsally and the external capsule/extreme capsule system ventrally. Additionally, commissural fibers seem to connect the bilateral intraparietal sulci when number magnitude information is processed. Finally, the identification of projection fibers such as the superior corona radiata indicates connections between cortex and basal ganglia as well as the thalamus in numerical cognition. Studies on functional/effective connectivity further indicated a specific role of the hippocampus. These specifications of brain connectivity augment the triple-code model of number processing and calculation with respect to how gray matter areas associated with specific number-related representations may work together.

Cognitive deficits in pediatric-onset multiple sclerosis: what does the future hold?

Pediatric-onset multiple sclerosis is relatively rare and research regarding disease characteristics is in its infancy. Regardless, there are a growing number of studies finding early cognitive deficits in this population. There are some similarities in outcomes to those seen in the adult-onset multiple sclerosis population, but also several important differences. With specific regard to cognitive functioning in pediatric-onset multiple sclerosis, there is evidence of deficit in nearly a third of patients, with impairment primarily in areas of processing speed, visual-spatial processing and language. There are additional findings of fatigue and depression that impact functional outcomes requiring further attention in assessment and treatment considerations. This paper also explores other areas requiring increased focus, including treatment and outcomes, neuroimaging and additional disease-modifying factors (comorbidities, socioeconomic status, race and so on).

Multiple sclerosis in children: an update on clinical diagnosis, therapeutic strategies, and research

The clinical features, diagnostic challenges, neuroimaging appearance, therapeutic options, and pathobiological research progress in childhood-and adolescent-onset multiple sclerosis have been informed by many new insights in the past 7 years. National programmes in several countries, collaborative research efforts, and an established international paediatric multiple sclerosis study group have contributed to revised clinical diagnostic definitions, identified clinical features of multiple sclerosis that differ by age of onset, and made recommendations regarding the treatment of paediatric multiple sclerosis. The relative risks conveyed by genetic and environmental factors to paediatric multiple sclerosis have been the subject of several large cohort studies. MRI features have been characterised in terms of qualitative descriptions of lesion distribution and applicability of MRI aspects to multiple sclerosis diagnostic criteria, and quantitative studies have assessed total lesion burden and the effect of the disease on global and regional brain volume. Humoral-based and cell-based assays have identified antibodies against myelin, potassium-channel proteins, and T-cell profiles that support an adult-like T-cell repertoire and cellular reactivity against myelin in paediatric patients with multiple sclerosis. Finally, the safety and efficacy of standard first-line therapies in paediatric multiple sclerosis populations are now appreciated in more detail, and consensus views on the future conduct and feasibility of phase 3 trials for new drugs have been proposed.

School performance as a marker of cognitive decline prior to diagnosis of multiple sclerosis

Background:

For many years, cognitive impairment has been established as a well-known symptom of multiple sclerosis. Moreover, we know that it was present even at the beginning of the disease.

Objective:

In this case-control study, we decided to evaluate whether there is an impairment of cognitive functions even before onset in those patients who will eventually suffer from multiple sclerosis.

Methods:

We evaluated the overall school performance, and particularly school performance in math and language in a group of patients who would later develop the disease and we compared our findings with a control group.

Results:

We found that school performance was poorer in subjects who were to become patients. And we found that the later the start of the first symptom, the better the qualifications.

Conclusion:

Testing a premorbid cognitive deficit by a validated indirect evaluation method allowed us to verify that there was evidence of neurological compromise even before a clinical diagnosis or the completion of the first magnetic resonance imaging in patients who would then suffer from multiple sclerosis.

Cognitive dysfunction in pediatric multiple sclerosis

Cognitive and neuropsychological impairments are well documented in adult multiple sclerosis (MS). Research has only recently focused on cognitive disabilities in pediatric cases, highlighting some differences between pediatric and adult cases. Impairments in several functions have been reported in children, particularly in relation to attention, processing speed, visual-motor skills, and language. Language seems to be particularly vulnerable in pediatric MS, unlike in adults in whom it is usually preserved. Deficits in executive functions, which are considered MS-specific in adults, have been inconsistently reported in children. In children, as compared to adults, the relationship between cognitive dysfunctions and the two other main symptoms of MS, fatigue and psychiatric disorders, was poorly explored. Furthermore, data on the correlations of cognitive impairments with clinical and neuroimaging features are scarce in children, and the results are often incongruent; interestingly, involvement of corpus callosum and reduced thalamic volume differentiated patients identified as having a cognitive impairment from those without a cognitive impairment. Further studies about pediatric MS are needed in order to better understand the impact of the disease on brain development and the resulting effect on cognitive functions, particularly with respect to different therapeutic strategies.

Left fronto-parietal white matter correlates with individual differences in children's ability to solve additions and multiplications: a tractography study

Functional neuroimaging data have pointed to the activation of a fronto-parietal network during calculation tasks, the activity of which is modulated by arithmetic operation and arithmetical competence. As the cortical brain regions of this network are distant, it is crucial to investigate the white matter connections between them and to examine how these connections are related to different arithmetic operations and individual differences in arithmetical competence. By using diffusion tensor imaging (DTI) tractography in eighteen 12-year-olds, we tested whether white matter pathways connecting these distant regions were related to children's arithmetical competence and how this association was modulated by operation. For each child, we delineated the three subcomponents of the arcuate fasciculus, a bundle of pathways linking frontal and temporo-parietal regions that are commonly active during calculation tasks. Fractional anisotropy in the left anterior portion of the arcuate fasciculus was positively correlated with addition and multiplication, but not with subtraction and division, suggesting a specific role of this left anterior segment in the solution of those problems that are expected to be solved with fact retrieval. The observed correlation was not explained by age, intelligence and working memory. Follow-up control analyses using different types of reading measures revealed that the observed correlation only disappeared when measures that draw heavily on phonological processing, such as non-word reading, were controlled for, suggesting that the association between the left arcuate fasciculus-anterior and addition/multiplication reflects the involvement of phonological processing. These results are the first to demonstrate that individual differences in fronto-parietal white matter are associated with arithmetical competence in typically developing children of a very narrow age range and indicate that this association is modulated by arithmetic operation.

Developmental dyscalculia: a dysconnection syndrome?

Numerical understanding is important for everyday life. For children with developmental dyscalculia (DD), numbers and magnitudes present profound problems which are thought to be based upon neuronal impairments of key regions for numerical understanding. The aim of the present study was to investigate possible differences in white matter fibre integrity between children with DD and controls using diffusion tensor imaging. White matter integrity and behavioural measures were evaluated in 15 children with developmental dyscalculia aged around 10 years and 15 matched controls. The main finding, obtained by a whole brain group comparison, revealed reduced fractional anisotropy in the superior longitudinal fasciculus in children with developmental dyscalculia. In addition, a region of interest analysis exhibited prominent deficits in fibres of the superior longitudinal fasciculus adjacent to the intraparietal sulcus, which is thought to be the core region for number processing. To conclude, our results outline deficient fibre projection between parietal, temporal and frontal regions in children with developmental dyscalculia, and therefore raise the question of whether dyscalculia can be seen as a dysconnection syndrome. Since the superior longitudinal fasciculus is involved in the integration and control of distributed brain processes, the present results highlight the importance of considering broader domain-general mechanisms in the diagnosis and therapy of dyscalculia.

DTI Measurements in Multiple Sclerosis: Evaluation of Brain Damage and Clinical Implications

Diffusion tensor imaging (DTI) is an effective means of quantifying parameters of demyelination and axonal loss. The application of DTI in Multiple Sclerosis (MS) has yielded noteworthy results. DTI abnormalities, which are already detectable in patients with clinically isolated syndrome (CIS), become more pronounced as disease duration and neurological impairment increase. The assessment of the microstructural alterations of white and grey matter in MS may shed light on mechanisms responsible for irreversible disability accumulation. In this paper, we examine the DTI analysis methods, the results obtained in the various tissues of the central nervous system, and correlations with clinical features and other MRI parameters. The adoption of DTI metrics to assess the outcome of prognostic measures may represent an extremely important step forward in the MS research field.

Cognitive impairment occurs in children and adolescents with multiple sclerosis: results from a United States network

In the largest sample studied to date, we measured cognitive functioning in children and adolescents with pediatric multiple sclerosis (n = 187) as well as those with clinically isolated syndrome (n = 44). Participants were consecutively enrolled from six United States Pediatric Multiple Sclerosis Centers of Excellence. Participants had a mean of 14.8 ± 2.6 years of age and an average disease duration of 1.9 ± 2.2 years. A total of 65 (35%) children with multiple sclerosis and 8 (18%) with clinically isolated syndrome met criteria for cognitive impairment. The most frequent areas involved were fine motor coordination (54%), visuomotor integration (50%), and speeded information processing (35%). A diagnosis of multiple sclerosis (odds ratio = 3.60, confidence interval = 1.07, 12.36, P = .04) and overall neurologic disability (odds ratio = 1.47, confidence interval = 1.10, 2.10, P = .03) were the only independent predictors of cognitive impairment. Cognitive impairment may occur early in these patients, and prompt recognition is critical for their care.

Individual differences in left parietal white matter predict math scores on the Preliminary Scholastic Aptitude Test

Mathematical skills are of critical importance, both academically and in everyday life. Neuroimaging research has primarily focused on the relationship between mathematical skills and functional brain activity. Comparatively few studies have examined which white matter regions support mathematical abilities. The current study uses diffusion tensor imaging (DTI) to test whether individual differences in white matter predict performance on the math subtest of the Preliminary Scholastic Aptitude Test (PSAT). Grades 10 and 11 PSAT scores were obtained from 30 young adults (ages 17-18) with wide-ranging math achievement levels. Tract based spatial statistics was used to examine the correlation between PSAT math scores, fractional anisotropy (FA), radial diffusivity (RD) and axial diffusivity (AD). FA in left parietal white matter was positively correlated with math PSAT scores (specifically in the left superior longitudinal fasciculus, left superior corona radiata, and left corticospinal tract) after controlling for chronological age and same grade PSAT critical reading scores. Furthermore, RD, but not AD, was correlated with PSAT math scores in these white matter microstructures. The negative correlation with RD further suggests that participants with higher PSAT math scores have greater white matter integrity in this region. Individual differences in FA and RD may reflect variability in experience dependent plasticity over the course of learning and development. These results are the first to demonstrate that individual differences in white matter are associated with mathematical abilities on a nationally administered scholastic aptitude measure.