Quantitative brain MRI morphology in severe and attenuated forms of mucopolysaccharidosis type I.

OBJECTIVE: To assess our hypothesis that brain macrostructure is different in individuals with mucopolysaccharidosis type I (MPS I) and healthy controls (HC), we conducted a comprehensive multicenter study using a uniform quantitative magnetic resonance imaging (qMRI) protocol, with analyses that account for the effects of disease phenotype, age, and cognition. METHODS: Brain MRIs in 23 individuals with attenuated (MPS IA) and 38 with severe MPS I (MPS IH), aged 4-25 years, enrolled under the study protocol NCT01870375, were compared to 98 healthy controls. RESULTS: Cortical and subcortical gray matter, white matter, corpus callosum, ventricular and choroid plexus volumes in MPS I significantly differed from HC. Thicker cortex, lower white matter and corpus callosum volumes were already present at the youngest MPS I participants aged 4-5 years. Age-related differences were observed in both MPS I groups, but most markedly in MPS IH, particularly in cortical gray matter metrics. IQ scores were inversely associated with ventricular volume in both MPS I groups and were positively associated with cortical thickness only in MPS IA. CONCLUSIONS: Quantitatively-derived MRI measures distinguished MPS I participants from HC as well as severe from attenuated forms. Age-related neurodevelopmental trajectories in both MPS I forms differed from HC. The extent to which brain structure is altered by disease, potentially spared by treatment, and how it relates to neurocognitive dysfunction needs further exploration.

Differences in MPS I and MPS II Disease Manifestations.

Mucopolysaccharidosis (MPS) type I and II are two closely related lysosomal storage diseases associated with disrupted glycosaminoglycan catabolism. In MPS II, the first step of degradation of heparan sulfate (HS) and dermatan sulfate (DS) is blocked by a deficiency in the lysosomal enzyme iduronate 2-sulfatase (IDS), while, in MPS I, blockage of the second step is caused by a deficiency in iduronidase (IDUA). The subsequent accumulation of HS and DS causes lysosomal hypertrophy and an increase in the number of lysosomes in cells, and impacts cellular functions, like cell adhesion, endocytosis, intracellular trafficking of different molecules, intracellular ionic balance, and inflammation. Characteristic phenotypical manifestations of both MPS I and II include skeletal disease, reflected in short stature, inguinal and umbilical hernias, hydrocephalus, hearing loss, coarse facial features, protruded abdomen with hepatosplenomegaly, and neurological involvement with varying functional concerns. However, a few manifestations are disease-specific, including corneal clouding in MPS I, epidermal manifestations in MPS II, and differences in the severity and nature of behavioral concerns. These phenotypic differences appear to be related to different ratios between DS and HS, and their sulfation levels. MPS I is characterized by higher DS/HS levels and lower sulfation levels, while HS levels dominate over DS levels in MPS II and sulfation levels are higher. The high presence of DS in the cornea and its involvement in the arrangement of collagen fibrils potentially causes corneal clouding to be prevalent in MPS I, but not in MPS II. The differences in neurological involvement may be due to the increased HS levels in MPS II, because of the involvement of HS in neuronal development. Current treatment options for patients with MPS II are often restricted to enzyme replacement therapy (ERT). While ERT has beneficial effects on respiratory and cardiopulmonary function and extends the lifespan of the patients, it does not significantly affect CNS manifestations, probably because the enzyme cannot pass the blood-brain barrier at sufficient levels. Many experimental therapies, therefore, aim at delivery of IDS to the CNS in an attempt to prevent neurocognitive decline in the patients.

An evaluation of computerized attention and executive function measures for use with school age children with neurofibromatosis type 1.

The present study investigated the performance of children with neurofibromatosis type 1 on computerized assessments of attention and executive function. Relations to ADHD symptomatology were also examined. Participants included 37 children (20 male) with NF1 (9-13 years; Mage = 11.02). Participants completed the NIH Toolbox Dimensional Change Card Sort, List Sort Working Memory (LSWM), and Flanker tasks, as well as Cogstate Identification and One Back tests. ADHD symptomatology was assessed using the K-SADS. Average performance was significantly different from the normative mean on every measure, except LSWM. The NIH Toolbox Flanker and Cogstate Identification tasks detected the highest proportion of participants with at least mild difficulty, and the Cogstate Identification task detected the highest proportion of participants with severe difficulty. Analyses revealed significant relations with ADHD symptomatology for two NIH toolbox tasks. The various computerized measures of attention and executive function offer different information when working with school age children with NF1. The NIH Flanker may offer the most room for change and offers face validity, which may be beneficial for clinical trials research. However, the LSWM shows most support for relations with behavioral indicators of attention and executive challenges.

The Behavioral Phenotype of 7q11.23 Duplication Syndrome Includes Risk for Oppositional Behavior and Aggression.

OBJECTIVE: 7q11.23 duplication syndrome (Dup7) is a genetic disorder with a variable phenotype associated with cognitive and behavioral characteristics including a high incidence of expressive language difficulties, social anxiety, and oppositional or disruptive behavior. Correlates of aggression and oppositionality were examined. METHOD: Participants were 63 children with genetically confirmed Dup7 between the ages of 4 and 17 years. A multimethod, multi-informant approach was used to assess aggression and oppositional behavior, and the contributions of cognitive functioning, expressive language, autism spectrum, social anxiety, and hyperactivity/impulsivity (H/I) symptomatology were considered. RESULTS: Elevated levels of aggression and oppositional behavior were found. Cognitive functioning, expressive language, and autism spectrum disorder symptomatology were not significantly related to parent ratings of aggression, although young children who had language and nonverbal cognitive delays were most likely to demonstrate examiner-observed aggression. Social anxiety and H/I symptomatology were related to defiant/aggressive and oppositional behavior. CONCLUSION: Genes in the 7q11.23 region duplicated in Dup7, in transaction with the environment, may contribute to aggressive and oppositional behavior.

Parent-Reported Social Skills in Children with Neurofibromatosis Type 1: Longitudinal Patterns and Relations with Attention and Cognitive Functioning.

OBJECTIVE: Social skills difficulties are commonly reported by parents and teachers of school age (SA) children with neurofibromatosis type 1 (NF1). Investigations of social skills of young children with NF1 are scarce. This study aimed to characterize the emergence of social skills challenges beginning in early childhood, examine social skills longitudinally into SA, and explore interrelations with attention-deficit hyperactivity disorder (ADHD) symptomatology and cognitive functioning among children with NF1 cross-sectionally and longitudinally. METHOD: Three samples of children with NF1 and their parents participated: (1) early childhood (n = 50; ages 3-6; mean [M] = 3.96, SD = 1.05), (2) SA (n = 40; ages 9-13; [M] = 10.90, SD = 1.59), and (3) both early childhood and SA (n = 25). Parent-reported social skills (Social Skills Rating System and Social Skills Improvement System), ADHD symptomatology (Conners Parent Rating Scales - Revised and Conners - Third Edition), and parent-reported cognitive abilities (Differential Ability Scales - Second Edition) were evaluated. RESULTS: Parental ratings of social skills were relatively stable throughout childhood. Ratings of social skills at the end of early childhood significantly predicted school-age social skills. Parental ratings of ADHD symptomatology showed significant negative relations with social skills. Early childhood inattentive symptoms predicted school-age social skills ratings. Cognitive functioning was not significantly related to social skills. CONCLUSION: Parent-reported social skills difficulties are evident during early childhood. This work adds to the literature by describing the frequency and stability of social skills challenges in early childhood and in the school-age period in NF1. Research about interventions to support social skills when difficulties are present is needed.

A Psychometric Analysis of the Social Anxiety Scale for Adolescents Among Youth With Autism Spectrum Disorder: Caregiver-Adolescent Agreement, Factor Structure, and Validity.

Social anxiety is common among adolescents with autism spectrum disorder (ASD). An ongoing challenge for both research and clinical practice in ASD is the assessment of anxious symptomatology. Despite its widespread use in samples of youth with ASD, the Social Anxiety Scale for Adolescents (SAS-A) has not received psychometric evaluation within this population; thus, the validity of its use in research and clinical practice for ASD remains unclear. The present study conducted a psychometric analysis of caregiver and adolescent SAS-A forms in a sample of adolescents with ASD (N = 197). Results revealed (1) poor caregiver-adolescent item-level agreement, (2) a two-factor structure, (3) lack of measurement invariance between reporters, and (4) modest evidence for convergent and discriminant validity. Overall, findings suggest that this measure demonstrates reasonable psychometric properties in an ASD sample. Lack of measurement invariance, however, calls for careful interpretation of research involving the SAS-A in ASD samples, particularly when the primary goal is to compare adolescent and caregiver reports. The implications of these findings for future research and clinical practice are discussed.

Adaptive Behavior and Executive Functioning in Children with Neurofibromatosis Type 1 Using a Mixed Design.

OBJECTIVE: Children with neurofibromatosis type 1 (NF1) demonstrate poorer adaptive functioning compared with same-aged peers; however, there is limited research about the longitudinal pattern of adaptive behavior. The aim of this investigation was to examine parent-reported adaptive behavior of children with NF1 longitudinally beginning in early childhood and to examine relations with executive functioning. METHOD: Children with NF1 were assessed during early childhood (n = 59; aged 3-7; mean = 4.8, SD = 1.42) or school age (n = 39; aged 9-13; mean = 10.85, SD = 1.58), and a subset was seen at both time points (n = 26). The Scales of Independent Behavior-Revised was used to assess adaptive functioning, and the Behavior Rating Inventory of Executive Function-Preschool Version/Behavior Rating Inventory of Executive Function was used to evaluate everyday executive functioning. RESULTS: Adaptive behavior in early childhood was significantly correlated with adaptive behavior at school age (with the exception of social interaction and communication skills) and was significantly poorer at school age. The frequency of difficulties increased over time for overall adaptive behavior and motor skills. Executive functioning was related to adaptive behavior cross-sectionally within early childhood and at school age and showed longitudinal predictive value over time. CONCLUSION: This research contributes to the limited NF1 adaptive behavior literature by characterizing the longitudinal pattern of adaptive behavior and relations with executive abilities.

Changes in Depressive Symptoms Among Adolescents with ASD Completing the PEERS® Social Skills Intervention.

Depression is a common concern among people with autism spectrum disorder (ASD) and is often associated with social skills and relationship challenges. The present data, from a randomized controlled trial, examined the effect of PEERS® on self-reported depressive symptoms via the Children's Depression Inventory (CDI) among 49 adolescents with ASD. Findings revealed that many CDI subscale scores declined (p's < 0.05) and were related to direct social contact on the Quality of Socialization Questionnaire at posttest (p's < 0.05). Exploratory analyses uncovered that suicidality was less evident following PEERS®. Findings support the notion that social functioning and depression may be intimately intertwined in ASD; therefore, bolstering social skills in ASD may positively influence other domains of functioning, including mental health.

Methods of neurodevelopmental assessment in children with neurodegenerative disease: Sanfilippo syndrome.

OBJECTIVES: (1) Develop a methodology for obtaining reliable cognitive and developmental data in children with neurodegenerative disease and cognitive impairment and in turn monitor disease state and treatment outcomes. (2) Demonstrate validity of age-equivalent scores. METHODS: We present guidelines for obtaining accurate test scores in low-functioning and behaviorally disruptive pediatric patients, followed by a method validation study: (1) using disease-specific protocols to assess salient aspects of the known phenotype, (2) selecting appropriate tests, (3) managing behavior, and (4) using age-equivalent scores on standardized tools. We used the Bayley Scales of Infant Development-III or Kaufman Assessment Battery for Children-II with a group of 25 children with mucopolysaccharidosis type IIIA (MPS IIIA or Sanfilippo syndrome type A) with dementia. To demonstrate concurrent validity, we used the Vineland Adaptive Behavior Scales-II, comparing parent-reported age-equivalent scores (AEs) with those of the cognitive measures. RESULTS: We were successful in obtaining cognitive age-equivalents for 25 patients with MPS IIIA including those with severe behavioral disruption and a correlation of 0.95 was obtained comparing scores on the parent measure with cognitive age-equivalents validating the age-equivalent approach. CONCLUSION: An approach to the assessment of severely impaired children including those with behavioral disruption was implemented and is applicable to children with other severe neurological diseases. This approach will enhance the assessment of disease progression and monitoring of treatment outcome in clinical trials.