Dementia in Childhood: Issues in Neuropsychological Assessment with Application to the Natural History and Treatment of Degenerative Storage Diseases

Buffy Coat Score as a Biomarker of Treatment Response in Neuronal Ceroid Lipofuscinosis Type 2

The introduction of intracerebroventricular (ICV) enzyme replacement therapy (ERT) for treatment of neuronal ceroid lipofuscinosis type 2 (CLN2) disease has produced dramatic improvements in disease management. However, assessments of therapeutic effect for ICV ERT are limited to clinical observational measures, namely the CLN2 Clinical Rating Scale, a subjective measure of motor and language performance. There is a need for an objective biomarker to enable assessments of disease progression and response to treatment. To address this, we investigated whether the proportion of cells with abnormal storage inclusions on electron microscopic examination of peripheral blood buffy coats could act as a biomarker of disease activity in CLN2 disease. We conducted a prospective longitudinal analysis of six patients receiving ICV ERT. We demonstrated a substantial and continuing reduction in the proportion of abnormal cells over the course of treatment, whereas symptomatic scores revealed little or no change over time. Here, we proposed the use of the proportion of cells with abnormal storage as a biomarker of response to therapy in CLN2. In the future, as more tissue-specific biomarkers are developed, the buffy coats may form part of a panel of biomarkers in order to give a more holistic view of a complex disease.

Natural History Studies in NCL and Their Expanding Role in Drug Development: Experiences From CLN2 Disease and Relevance for Clinical Trials

Conducting clinical trials in rare diseases is challenging. In trials that aim to use natural history control cohorts for evaluation of efficacy, lack of data on natural history of disease prolongs development of future therapies significantly. Therefore, collection of valid natural history data in clinical settings is needed to advance drug development. These data need to fulfill requirements on type of collection, quantifiable measures on the course of disease, verification and monitoring as well as compliance to strict data protection and sharing policies. Disease registries can be a source for patient data. Late-infantile CLN2 disease is characterized by rapid psychomotor decline and epilepsy. Natural-history data of 140 genotype-confirmed CLN2 patients from two independent, international cohorts were analyzed in a natural history study. Both datasets included quantitative ratings with disease-specific clinical scores. Among 41 patients for whom longitudinal assessments spanning an extended disease course were available within the DEM-CHILD DB (an international NCL disease patient database, NCT04613089), a rapid loss of motor and language abilities was documented in quantitative detail. Data showed that the course of disease in late-infantile CLN2 disease is highly predictable with regard to the loss of language and motor function and that the results were homogeneous across multiple and international sites. These data were accepted by EMA and FDA as valid natural-history controls for the evaluation of efficacy in experimental therapies for CLN2 disease and led to an expedited approval of intracerebroventricular enzyme replacement therapy with cerliponase alpha in May 2017.

Dementia Risk among Coronavirus Disease Survivors: A Nationwide Cohort Study in South Korea

We aimed to investigate whether coronavirus disease (COVID-19) survivors were at a higher risk of dementia diagnosis compared to controls at 6 months follow-up. Data pertaining to the period between 1 January and 4 June 2020, were extracted from the National Health Insurance Service (NHIS)-COVID-19 database in South Korea. Data on adults (≥20 years old) with no history of dementia, obtained from the NHIS-COVID-19 database, were included in the study. The endpoint of this study was the development of dementia, which was evaluated from 1 January to 1 December 2020. A total of 306,577 adults were included in the analysis, comprising 7133 COVID-19 survivors and 299,444 individuals in the control group. Among the subjects, new-onset dementia diagnosed in 2020 was recorded in 1.2% (3546 of 306,577). In the covariate-adjusted multivariable Cox regression model, the incidence of dementia among COVID-19 survivors was 1.39-fold higher (hazard ratio: 1.39, 95% confidence interval: 1.05–1.85; p = 0.023) than that in the control group. At approximately 6 months of follow-up, COVID-19 survivors were at a higher risk of dementia compared to other populations in South Korea.

The natural history of neurocognition in MPS disorders: A review

MPS disorders are associated with a wide spectrum of neurocognitive effects, from mild problems with attention and executive functions to progressive and degenerative neuronopathic disease. Studies of the natural history of neurocognition are necessary to determine the profile of abnormality and the rates of change, which are crucial to select endpoints for clinical trials of brain treatments and to make clinical recommendations for interventions to improve patients' quality of life. The goal of this paper is to review neurocognitive natural history studies to determine the current state of knowledge and assist in directing future research in all MPS disorders. There are seven different types of MPS diseases, each resulting from a specific enzyme deficiency and each having a separate natural history. MPS IX, will not be discussed as there are only 4 cases reported in the literature without cognitive abnormality. For MPS IH, hematopoietic cell transplant (HCT) is standard of care and many studies have documented the relationship between age at treatment and neurocognitive outcome, and to a lesser extent, neurocognitive status at baseline. However, the mortality and morbidity associated with the transplant process and residual long-term problems after transplant, have led to renewed efforts to find better treatments. Rather than natural history, new trials will likely need to use the developmental trajectories of the patients with HCT as a comparators. The literature has extensive data regarding developmental trajectories post-HCT. For attenuated MPS I, significant neurocognitive deficits have been documented, but more longitudinal data are needed in order to support a treatment directed at their attention and executive function abnormalities. The neuronopathic form of MPS II has been a challenge due to the variability of the trajectory of the disease with differences in timing of slowing of development and decline. Finding predictors of the course of the disease has only been partially successful, using mutation type and family history. Because of lack of systematic data and clinical trials that precede a thorough understanding of the disease, there is need for a major effort to gather natural history data on the entire spectrum of MPS II. Even in the attenuated disease, attention and executive function abnormalities need documentation. Lengthy detailed longitudinal studies are needed to encompass the wide variability in MPS II. In MPS IIIA, the existence of three good natural history studies allowed a quasi-meta-analysis. In patients with a rapid form of the disease, neurocognitive development slowed up until 42 to 47 months, halted up to about 54 months, then declined rapidly thereafter, with a leveling off at an extremely low age equivalent score below 22 months starting at about chronological age of 6. Those with slower or attenuated forms have been more variable and difficult to characterize. Because of the plethora of studies in IIIA, it has been recommended that data be combined from natural history studies to minimize the burden on parents and patients. Sufficient data exists to understand the natural history of cognition in MPS IIIA. MPS IIIB is quite similar to IIIA, but more attenuated patients in that phenotype have been reported. MPS IIIC and D, because they are so rare, have little documentation of natural history despite the prospects of treatments. MPS IV and VI are the least well documented of the MPS disorders with respect to their neurocognitive natural history. Because, like attenuated MPS I and II, they do not show progression of neurocognitive abnormality and most patients function in the range of normality, their behavioral, attentional, and executive function abnormalities have been ignored to the detriment of their quality of life. A peripheral treatment for MPS VII, extremely rare even among MPS types, has recently been approved with a post-approval monitoring system to provide neurocognitive natural history data in the future. More natural history studies in the MPS forms with milder cognitive deficits (MPS I, II, IV, and VI) are recommended with the goal of improving these patients' quality of life with and without new brain treatments, beyond the benefits of available peripheral enzyme replacement therapy. Recommendations are offered at-a-glance with respect to what areas most urgently need attention to clarify neurocognitive function in all MPS types.

NPC1 deficiency impairs cerebellar postnatal development of microglia and climbing fiber refinement in a mouse model of Niemann-Pick disease type C

Little is known about the effects of NPC1 deficiency in brain development and whether these effects contribute to neurodegeneration in Niemann–Pick disease type C (NPC). Degeneration of cerebellar Purkinje cells occurs at an earlier stage and to a greater extent in NPC; therefore, we analyzed the effect of NPC1 deficiency on microglia and on climbing fiber synaptic refinement during cerebellar postnatal development using the Npc1^nmf164 mouse. Our analysis revealed that NPC1 deficiency leads to early phenotypic changes in microglia that are not associated with an innate immune response. However, the lack of NPC1 in Npc1^nmf164 mice significantly affected the early development of microglia by delaying the radial migration, increasing the proliferation and impairing the differentiation of microglia precursor cells during postnatal development. Additionally, increased phagocytic activity of differentiating microglia was observed at the end of the second postnatal week in Npc1^nmf164 mice. Moreover, significant climbing fiber synaptic refinement deficits along with an increased engulfment of climbing fiber synaptic elements by microglia were found in Npc1^nmf164 mice, suggesting that profound developmental defects in microglia and synaptic connectivity might precede and predispose Purkinje cells to early neurodegeneration in NPC.

Summary: Genetic deficiency of Npc1 impairs postnatal development of microglia and climbing fiber synaptic pruning in the mouse cerebellum.

Overview of advances in educational and social supports for young persons with NCL disorders

Vision loss, dementia, and motor and speech declines all impact the educational experience of individuals with Batten disease and can adversely impact effective learning. There are as yet limited data to support evidence-based approaches to meeting the educational needs of affected individuals. This paper provides an overview of recent work to evaluate and address educational issues with a life-long perspective relevant to individuals with juvenile-onset neuronal ceroid lipofuscinosis (JNCL) and the professionals that provide them with educational support. In particular, several main activities of the recently completed 'JNCL and Education' project are summarised, including a survey of parents, educational professionals and social/health workers, development of a formative assessment tool to identify and respond to an individual student's strengths and needs in the learning environment, and proposed strategies for prolonging literacy and language skills. A key concept that should be emphasised in the educational plan for students with JNCL is that of 'proactive' and 'hastened' learning, that is, providing an early emphasis on adaptive skills that will be required in the later stages of disease progression when new learning will be more difficult to achieve. An additional key concept is participation in real-life activities to maintain skills and quality of life, particularly in the later stages of disease progression.

Microglia: The Effector Cell for Reconstitution of the Central Nervous System following Bone Marrow Transplantation for Lysosomal and Peroxisomal Storage Diseases

Treatment and potential cure of lysosomal and peroxisomal diseases, heretofore considered fatal, has become a reality during the past decade. Bone marrow transplantation, (BMT), has provided a method for replacement of the disease-causing enzyme deficiency. Cells derived from the donor marrow continue to provide enzyme indefinitely. Several scores of patients with diseases as diverse as metachromatic leukodystrophy, adrenoleukodystrophy, globoid cell leukodystrophy, Hurler syndrome (MPS I-H), Maroteaux-Lamy (MPS VI) Gaucher disease, and fucosidosis have been successfully treated following long-term engraftment. Central nervous system (CNS) manifestations are also prevented or ameliorated in animal models of these diseases following engraftment from normal donors. The microglial cell system has been considered to be the most likely vehicle for enzyme activity following bone marrow engraftment. Microglia in the mature animal or human are derived from the newly engrafted bone marrow. Graft-v-host disease activation of the microglia is also of importance. This article will summarize some of the pertinent literature relative to the role of microglia in such transplant processes.

Therapy of X-linked adrenoleukodystrophy: prognosis based upon age and MRI abnormality and plans for placebo-controlled trials

Evaluation of the therapy of X-linked adrenoleukodystrophy (X-ALD) is hampered by its rarity and by the striking and unpredictable variation in phenotypic expression. We present two approaches that may facilitate therapy evaluation. (1) We have analysed data on 377 X-ALD patients who have been followed at the Kennedy Krieger Institute for a mean period of 38 months and have subdivided them into 18 subgroups on the basis of age and the degree of abnormality in brain magnetic resonance imaging (MRI) as assessed by the Loes score (Am. J. Neuroradrol 1994; 15: 1761). We find that grouping on the basis of age and MRI score provides information that is of significant prognostic value. (2) We present plans for the development of a placebo-controlled multicentre international study that will have sufficient biostatistical power to provide objective evaluation of new therapeutic interventions.

Komrower Lecture. Adrenoleukodystrophy: natural history, treatment and outcome

Our laboratory has identified nearly 2000 patients with X-linked adrenoleukodystrophy (ALD) and conducted therapeutic trials in groups of patients who represent the major phenotypes. We report recent results of dietary therapy with a mixture of glyceryl trioleate and glyceryl trierucate oil, also referred to as Lorenzo's Oil, in the asymptomatic and childhood cerebral phenotypes. Fifty-three patients started this therapy at a mean age of 7.5 years at a time when they were free of neurological symptoms. Although analysis of data is hampered by the lack of a concurrent control group, follow-up studies after 39 months of therapy suggest that subsequent neurological involvement was less frequent and less severe than anticipated from historical controls. Retrospective analysis of the effect of the oil in patients with the severe childhood cerebral phenotype indicates that there was a slight but statistically significant slowing of clinical progression and delay of death.