Central nervous system connectivity after extreme prematurity: understanding autistic spectrum disorder

Optimizing trajectories of social adaptive competencies after extreme prematurity during the first 1000 days

Over 75% of surviving extremely preterm infants do not have major neurodevelopmental disabilities; however, more than half face difficulties with communication, coordination, attention, learning, social, and executive function abilities. These "minor" challenges can have a negative impact on educational and social outcomes, resulting in physical, behavioral, and social health problems in adulthood. We will review assessment tools for social-emotional and adaptive functional skills in early childhood as these determine family and early childhood supports. We highlight bronchopulmonary dysplasia as an example of the critical intersections of parental wellbeing, medical and developmental adaptive trajectories in infancy and early childhood, and partnerships between child neurologists and community medical and developmental professionals. We examine studies of engaging parents to promote developmental trajectories, with a focus on supporting parent-child interactions that underlie communication, social-adaptive behaviors, and learning in the first 1000 days of life. Recommendations for neurodevelopmental surveillance and screening of extremely preterm infants can also be applied to infants with other risk factors for altered neurodevelopment.

The critical importance of follow-up to school age: Contributions of the NICHD Neonatal Research Network

Follow-up studies are essential for understanding outcomes and informing the care of infants with high risk for medical and developmental consequences because of extreme prematurity or perinatal illness. Studies that extend to school age often identify sequelae that go unrecognized in neonatal or short-term follow-up studies. Many critical neurocognitive, behavioral, functional, and health outcomes are best assessed beginning at school age. The Eunice Kennedy Shriver National Institute of Child Health and Development Neonatal Research Network (NRN) has performed comprehensive school age evaluations of several key trial cohorts. This manuscript summarizes the important contributions of school age follow-up studies in the NRN, both historically and in ongoing research. We describe in detail the clinical questions that have been answered by the completed studies and new questions about the outcomes of high-risk infants that must be addressed by ongoing and future studies.

Behavioral and Socioemotional Development in Preterm Children

Prematurity is a significant risk factor for impaired neurodevelopmental outcomes. These include motor, cognitive, language, behavioral, and socioemotional competence. Long-term overall function depends on healthy socioemotional functioning. The vulnerability of the preterm brain during critical periods of development contributes to behavioral and socioemotional problems in preterm children. Attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) clinical features are more frequent in preterm children compared with their full-term counterparts; however, true rates of ASD and ADHD vary across studies. Early detection of behavioral and socioemotional problems in preterm children would enable timely early intervention to improve long-term functional outcomes.

Chondroitin sulfate proteoglycans inhibit the migration and differentiation of oligodendrocyte precursor cells and its counteractive interaction with laminin

Cerebral white matter injury (WMI) is a recognized problem in premature infants, particularly in those with very low birth weights. Although the survival rate of premature infants has notably increased due to the advancement of modern medical treatments, their likelihood of developmental disability is higher than infants with an average birth weight. It has been previously reported that oligodendrocyte precursor cells (OPCs) are selectively vulnerable to WMI in premature infants. Following brain injury, glial scars may develop within the white matter. Their main constituent is chondroitin sulphate proteoglycans (CSPGs), revealing a potential association between CSPGs and OPCs. In the present study rat OPCs were cultured in vitro, and the effect of CSPGs on the proliferation, migration and differentiation of OPCs was determined. It was revealed that CSPGs did not affect proliferation, but they did inhibit the migration and differentiation of OPCs. It was also identified that the inhibitory effect of CSPGs was counteracted by laminin. Factor analysis revealed that CSPGs and laminin served interactive roles in OPC differentiation. The effect of CSPGs on OPCs was associated with the downregulation of β1-integrin, indicating that CSPGs potentially competitively inhibit the β1-integrin signaling pathway. Collectively, these results suggest that CSPGs serve a role as inhibitors of OPC differentiation and migration, as well as indicating an interaction between CSPGs and laminin. The present study has revealed a potential novel therapeutic target for WMI in premature infants, and identified β1-integrin signaling as a pathological mechanism for dysfunctional myelination in white matter.

Stability of early risk assessment for autism spectrum disorder in preterm infants

Stability and change in early autism spectrum disorder risk were examined in a cohort of 99 preterm infants (⩽34 weeks of gestation) using the Autism Observation Scale for Infants at 8 and 12 months and the Autism Diagnostic Observation Schedule—Toddler Module at 18 months. A total of 21 infants were identified at risk by the Autism Observation Scale for Infants at 8 months, and 9 were identified at risk at 12 months, including 4 children who were not previously identified. At 18 months, eight children were identified at risk for autism spectrum disorder using the Autism Diagnostic Observation Schedule—Toddler Module, only half of whom had been identified using the original Autism Observation Scale for Infants cutoffs. Results are discussed in relation to early trajectories of autism spectrum disorder risk among preterm infants as well as identifying social-communication deficiencies associated with the early preterm behavioral phenotype.

Gestational age at birth and risk of autism spectrum disorders in Alberta, Canada

OBJECTIVE

To examine the association between autism spectrum disorders (ASD) and each completed week of gestation using a graphical method of presenting results at all possible categorizations of gestational age (GA).

STUDY DESIGN

The risk of ASD in a total of 218110 singleton live births with complete data from Alberta, Canada between 1998 and 2004 was examined through linkage to health insurance records. The relative risk of developing ASD according to the 21 dichotomizations of shorter gestation (GA ≤ 23 weeks vs >23 weeks to ≤ 43 weeks vs >43 weeks, in 1-week increments) was calculated using log-binomial regression and adjusted for fetal sex, socioeconomic status, and birth year.

RESULTS

We observed a gradual increased risk of ASD with shorter gestation. Cutoffs only between 29 and 40 weeks clearly denoted an elevated risk of developing ASD compared with longer gestation, and the risk increased with earlier GA cutoff. The results were not affected by sex or measures of fetal growth.

CONCLUSION

Our data confirm the role of shortened gestation in ASD risk. We warn against the use of prespecified or a data-driven GA cutoff, however; instead, we recommend systematically examining all plausible cutoffs for GA to avoid overstating the homogeneity of risk in children on either side of a given cutoff, as well as to increase the comparability of studies.

Reprint of "The developing oligodendrocyte: key cellular target in brain injury in the premature infant"

Brain injury in the premature infant, a problem of enormous importance, is associated with a high risk of neurodevelopmental disability. The major type of injury involves cerebral white matter and the principal cellular target is the developing oligodendrocyte. The specific phase of the oligodendroglial lineage affected has been defined from study of both human brain and experimental models. This premyelinating cell (pre-OL) is vulnerable because of a series of maturation-dependent events. The pathogenesis of pre-OL injury relates to operation of two upstream mechanisms, hypoxia-ischemia and systemic infection/inflammation, both of which are common occurrences in premature infants. The focus of this review and of our research over the past 15-20 years has been the cellular and molecular bases for the maturation-dependent vulnerability of the pre-OL to the action of the two upstream mechanisms. Three downstream mechanisms have been identified, i.e., microglial activation, excitotoxicity and free radical attack. The work in both experimental models and human brain has identified a remarkable confluence of maturation-dependent factors that render the pre-OL so exquisitely vulnerable to these downstream mechanisms. Most importantly, elucidation of these factors has led to delineation of a series of potential therapeutic interventions, which in experimental models show marked protective properties. The critical next step, i.e., clinical trials in the living infant, is now on the horizon.

The developing oligodendrocyte: key cellular target in brain injury in the premature infant

Brain injury in the premature infant, a problem of enormous importance, is associated with a high risk of neurodevelopmental disability. The major type of injury involves cerebral white matter and the principal cellular target is the developing oligodendrocyte. The specific phase of the oligodendroglial lineage affected has been defined from study of both human brain and experimental models. This premyelinating cell (pre-OL) is vulnerable because of a series of maturation-dependent events. The pathogenesis of pre-OL injury relates to operation of two upstream mechanisms, hypoxia-ischemia and systemic infection/inflammation, both of which are common occurrences in premature infants. The focus of this review and of our research over the past 15-20 years has been the cellular and molecular bases for the maturation-dependent vulnerability of the pre-OL to the action of the two upstream mechanisms. Three downstream mechanisms have been identified, i.e., microglial activation, excitotoxicity and free radical attack. The work in both experimental models and human brain has identified a remarkable confluence of maturation-dependent factors that render the pre-OL so exquisitely vulnerable to these downstream mechanisms. Most importantly, elucidation of these factors has led to delineation of a series of potential therapeutic interventions, which in experimental models show marked protective properties. The critical next step, i.e., clinical trials in the living infant, is now on the horizon.