Parental education accounts for variability in the IQs of probands with Down syndrome: A longitudinal study

The impact of social-environmental factors on IQ in syndromic intellectual developmental disabilities

Despite having the same underlying genetic etiology, individuals with the same syndromic form of intellectual developmental disability (IDD) show a large degree of interindividual differences in cognition and IQ. Research indicates that up to 80% of the variation in IQ scores among individuals with syndromic IDDs is attributable to nongenetic effects, including social-environmental factors. In this narrative review, we summarize evidence of the influence that factors related to economic stability (focused on due to its prevalence in existing literature) have on IQ in individuals with syndromic IDDs. We also highlight the pathways through which economic stability is hypothesized to impact cognitive development and drive individual differences in IQ among individuals with syndromic IDDs. We also identify broader social-environmental factors (e.g., social determinants of health) that warrant consideration in future research, but that have not yet been explored in syndromic IDDs. We conclude by making recommendations to address the urgent need for further research into other salient factors associated with heterogeneity in IQ. These recommendations ultimately may shape individual- and community-level interventions and may inform systems-level public policy efforts to promote the cognitive development of and improve the lived experiences of individuals with syndromic IDDs.

Correlating MRI-based brain volumetry and cognitive assessment in people with Down syndrome

INTRODUCTION

Down syndrome (DS) is the most common genetic cause of intellectual disability. Children and adults with DS show deficits in language performance and explicit memory. Here, we used magnetic resonance imaging (MRI) on children and adults with DS to characterize changes in the volume of specific brain structures involved in memory and language and their relationship to features of cognitive-behavioral phenotypes.

METHODS

Thirteen children and adults with the DS phenotype and 12 age- and gender-matched healthy controls (age range 4-25) underwent an assessment by MRI and a psychological evaluation for language and cognitive abilities.

RESULTS

The cognitive profile of people with DS showed deficits in different cognition and language domains correlating with reduced volumes of specific regional and subregional brain structures, confirming previous related studies. Interestingly, in our study, people with DS also showed more significant parahippocampal gyrus volumes, in agreement with the results found in earlier reports.

CONCLUSIONS

The memory functions and language skills affected in studied individuals with DS correlate significantly with the reduced volume of specific brain regions, allowing us to understand DS's cognitive-behavioral phenotype. Our results provide an essential basis for early intervention and the design of rehabilitation management protocols.

Cognitive profiles in children and adolescents with Down syndrome

The Down syndrome (DS) phenotype is usually characterized by relative strengths in non-verbal skills and deficits in verbal processing, but high interindividual variability has been registered in the syndrome. The goal of this study was to explore the cognitive profile, considering verbal and non-verbal intelligence, of children and adolescents with DS, also taking into account interindividual variability. We particularly aimed to investigate whether this variability means that we should envisage more than one cognitive profile in this population. The correlation between cognitive profile and medical conditions, parents’ education levels and developmental milestones was also explored. Seventy-two children/adolescents with DS, aged 7–16 years, were assessed with the Wechsler Preschool and Primary Scale of Intelligence-III. Age-equivalent scores were adopted, and Verbal and Non-Verbal indices were obtained for each individual. The cognitive profile of the group as a whole was characterized by similar scores in the verbal and non-verbal domain. Cluster analysis revealed three different profiles, however: one group, with the lowest scores, had the typical profile associated with DS (with higher non-verbal than verbal intelligence); one, with intermediate scores, had greater verbal than non-verbal intelligence; and one, with the highest scores, fared equally well in the verbal and non-verbal domain. Three cognitive profiles emerged, suggesting that educational support for children and adolescents with DS may need to be more specific.

Incomplete Penetrance and Variable Expressivity: From Clinical Studies to Population Cohorts

The same genetic variant found in different individuals can cause a range of diverse phenotypes, from no discernible clinical phenotype to severe disease, even among related individuals. Such variants can be said to display incomplete penetrance, a binary phenomenon where the genotype either causes the expected clinical phenotype or it does not, or they can be said to display variable expressivity, in which the same genotype can cause a wide range of clinical symptoms across a spectrum. Both incomplete penetrance and variable expressivity are thought to be caused by a range of factors, including common variants, variants in regulatory regions, epigenetics, environmental factors, and lifestyle. Many thousands of genetic variants have been identified as the cause of monogenic disorders, mostly determined through small clinical studies, and thus, the penetrance and expressivity of these variants may be overestimated when compared to their effect on the general population. With the wealth of population cohort data currently available, the penetrance and expressivity of such genetic variants can be investigated across a much wider contingent, potentially helping to reclassify variants that were previously thought to be completely penetrant. Research into the penetrance and expressivity of such genetic variants is important for clinical classification, both for determining causative mechanisms of disease in the affected population and for providing accurate risk information through genetic counseling. A genotype-based definition of the causes of rare diseases incorporating information from population cohorts and clinical studies is critical for our understanding of incomplete penetrance and variable expressivity. This review examines our current knowledge of the penetrance and expressivity of genetic variants in rare disease and across populations, as well as looking into the potential causes of the variation seen, including genetic modifiers, mosaicism, and polygenic factors, among others. We also considered the challenges that come with investigating penetrance and expressivity.

Relationship Between Social Motivation in Children With Autism Spectrum Disorder and Their Parents

Impairment in social motivation (SM) has been suggested as a key mechanism underlying social communication deficits observed in autism spectrum disorder (ASD). However, the factors accounting for variability in SM remain poorly described and understood. The current study aimed to characterize the relationship between parental and proband SM. Data from 2,759 children with ASD (M age = 9.03 years, SD age = 3.57, 375 females) and their parents from the Simons Simplex Collection (SSC) project was included in this study. Parental and proband SM was assessed using previously identified item sets from the Social Responsiveness Scale (SRS). Children who had parents with low SM scores (less impairments) showed significantly lower impairments in SM compared to children who had either one or both parents with elevated SM scores. No parent-of-origin effect was identified. No significant interactions were found involving proband sex or intellectual disability (ID) status (presence/absence of ID) with paternal or maternal SM. This study establishes that low SM in children with ASD may be driven, in part, by lower SM in one or both parents. Future investigations should utilize larger family pedigrees, including simplex and multiplex families, evaluate other measures of SM, and include other related, yet distinct constructs, such as social inhibition and anhedonia. This will help to gain finer-grained insights into the factors and mechanisms accounting for individual differences in sociability among typically developing children as well as those with, or at risk, for developing ASD.

The science of humanity and the humanity of science: Perspectives on Ed Zigler's contributions to developmental psychopathology and the study of all children

We present this article as a testament to Ed Zigler's commitment to science in the service of humanity and to policy based on conceptually compelling theory and methodologically rigorous science. In doing so, we highlight ways that Ed's universal and inclusive developmental world view, early training as a behaviorist, exacting scientific standards, concern for others, and appreciation of his own roots and upbringing all transformed the way that many different groups of people of all ages and backgrounds are studied, viewed, and intervened with by researchers, policy makers, and society at large. Ed's narrative of development rather than defect, universality rather than difference, and holistic rather than reductionist continues to compel us in the quest for a kinder, more inclusive, and enabling society. Conversely, Ed's behaviorist training as a graduate student also influenced him throughout his career and was essential to his career-long commitment to systemic action in the service of improving the lives of others. We cite the lessons that we, as his descendants, learned from Ed and apply them to our own areas of research with populations that Ed did not study, but had considerable interest in - persons with autism spectrum disorder and Indigenous youth.

Developmental Perspectives on the Study of Persons with Intellectual Disability

Developmental approaches provide inclusive, universal, and methodologically rigorous frameworks for studying persons with intellectual disability (ID). This is an exceptionally heterogeneous group with regard to etiology, genotype, and phenotype that simply shares the traditional diagnostic criteria, typically a score of two standard deviations below the population mean of 100 on standardized IQ tests and deficits in adaptive behavior. We trace the foundational, conceptual, and methodological roots of developmental approaches and highlight ways that these and more recent iterations continue to be central to advances in the increasingly nuanced study of persons with ID. This work is premised on the consideration of specific etiological groupings and subgroupings across and between different domains of functioning within the context of familial and complex environments throughout the life span. We highlight the potential contributions of advances in behavioral methodologies, genomics, and neuroscience when considered within universal and hierarchic frameworks based on development.

Family Variables and Quality of Life in Children with Down Syndrome: A Scoping Review

The purpose of this scoping review was to identify the family and child quality of life variables that have been studied in relation to one another in children with Down syndrome, the frequency with which different relationships have been studied, and the extent to which family variables were the focus of the research aims. A literature search was conducted to find studies published between January 2007 and June 2018. The initial search yielded 2314 studies; of these, 43 were selected for a final review. Researchers most often addressed family resources and family problem-solving and coping concerning child personal development and physical well-being. Little attention to child emotional well-being was observed, with none considering family appraisal of child emotional well-being. The relationship between family variables and child QoL rarely was the primary focus of the study. Methodologically, most reviewed studies used cross-sectional designs, were conducted in North America and based on maternal report. From future research considering the issues found in this review, healthcare providers can obtain an in-depth understanding of relationships between children and family variables.

Parent-Reported Contribution of Family Variables to the Quality of Life in Children with Down Syndrome: Report from an International Study

PURPOSE

The intent of this study was to determine parents' views of the contribution of family variables to the quality of life (QoL) of children with Down Syndrome (DS). Based on prior research, we hypothesized that parents would report that family variables reflecting positive aspects of family functioning contributed to better QoL; and family variables reflecting the negative aspects of family functioning contributed to poorer QoL.

DESIGN AND METHODS

A cross-sectional study was carried out. Invitation letters were sent to DS support groups. Upon agreement, the parents of the children were sent a link to an online survey that included a consent form, demographic questionnaire, and child and family measures.

RESULTS

Results demonstrated the contribution of family demands to children's interpersonal relations. Family appraisals concerning the child and the family's ability predicted the children's physical and material well-being, personal development, self-determination, social inclusion, interpersonal relations, and rights. Family problem-solving served as a prominent predictor for children's physical and emotional well-being, personal development, interpersonal relations, and rights. Also, family resources predicted various aspects of children's QoL including physical, emotional, and material well-being, self-determination, social inclusion, interpersonal relations, and rights.

CONCLUSION

Results confirmed the significant relationship between family and children's QoL variables. Family appraisal and family problem-solving were especially identified as significant predictors of children's QoL that can be targeted for family interventions, since the family variables are modifiable aspects of family life.

PRACTICE IMPLICATIONS

Nurses can use current findings to develop interventions to enhance QoL of children with DS and families.

Cost-effectiveness of genome-wide sequencing for unexplained developmental disabilities and multiple congenital anomalies

PURPOSE

Genetic testing is routine practice for individuals with unexplained developmental disabilities and multiple congenital anomalies. However, current testing pathways can be costly and time consuming, and the diagnostic yield low. Genome-wide sequencing, including exome sequencing (ES) and genome sequencing (GS), can improve diagnosis, but at a higher cost. This study aimed to assess the cost-effectiveness of genome-wide sequencing in Ontario, Canada.

METHODS

A cost-effectiveness analysis was conducted using a discrete event simulation from a public payer perspective. Six strategies involving ES or GS were compared. Outcomes reported were direct medical costs, number of molecular diagnoses, number of positive findings, and number of active treatment changes.

RESULTS

If ES was used as a second-tier test (after the current first-tier, chromosomal microarray, fails to provide a diagnosis), it would be less costly and more effective than standard testing (CAN$6357 [95% CI: 6179-6520] vs. CAN$8783 per patient [95% CI: 2309-31,123]). If ES was used after standard testing, it would cost an additional CAN$15,228 to identify the genetic diagnosis for one additional patient compared with standard testing. The results remained robust when parameters and assumptions were varied.

CONCLUSION

ES would likely be cost-saving if used earlier in the diagnostic pathway.

Gesell Developmental Schedules scores and the relevant factors in children with Down syndrome

Background Down syndrome (DS) is a common chromosomal disease resulting in neurodegeneration. Cognitive competence has been assessed among adults with DS using various methods because DS patients have a tendency to develop Alzheimer's disease (AD) after middle age. However, research describing cognitive assessments in DS children is not as many as in DS adults, let alone with regard to performed analyses to determine factors that predict cognitive assessments. In this study, we evaluated the Gesell Developmental Schedules (GDS) scores and their associations with the relevant biochemical indicators and demographic factors in DS children. Methods All the subjects underwent GDS testing. The plasma amyloid-β (Aβ) peptide and serum vitamin A (VA) values were measured with enzyme-linked immunosorbent assay and high-performance liquid chromatography, and in the meanwhile, the demographic information of the subjects was collected. Results Forty-six DS children were recruited for this study. The GDS scores of children with DS were lower than those in children without DS. The plasma Aβ40 and Aβ42 levels were negatively associated with the GDS scores. Moreover, the GDS scores of the non-VA deficiency (NVAD) group were significantly higher than those of the VA deficiency (VAD) group. Certain demographic characteristics, such as the paternal labor intensity and paternal educational status, were relevant factors with regard to the GDS scores of the DS children. Conclusions This study determined that DS children exhibited abnormal GDS scores which indicated developmental delay of children with DS; the levels of plasma Aβ40, Aβ42 and serum VA were influential biochemical indicators and the paternal labor intensity and educational status were related demographic factors.

Predisposing Factors for Elevated Restricted and Repetitive Behavior in Typically Developing Toddlers

Little is known about the relation between levels of restricted and repetitive behavior (RRB) in infants and parent factors. The present study investigated maternal and psychosocial factors (depressive symptoms, socio-economic status, social support) and mother-infant engagement factors (mind-mindedness, sensitivity, and infant-mother attachment security) as predictors of children's RRB at age 26 months in a sample of 206 mothers and children. Maternal depressive symptoms predicted levels of sensory and motor repetitive behavior and rigid, routinized, and ritualistic repetitive behavior. Lower socioeconomic status also predicted independent variance in children's sensory and motor repetitive behavior. The relations between maternal depressive symptoms and both types of RRB were not mediated through observational measures of maternal sensitivity or mind-mindedness at 8 months, or attachment security at 15 months. The results are discussed in terms of whether stress regulation, self-stimulation, and genetic susceptibility can help explain the observed link between maternal depressive symptoms and RRB in the child.