Object working memory deficits predicted by early brain injury and development in the preterm infant

Early versus late caffeine and/or non-steroidal anti-inflammatory drugs (NSAIDS) for prevention of intermittent hypoxia-induced neuroinflammation in the neonatal rat

Preterm infants often experience frequent intermittent hypoxia (IH) episodes which are associated with neuroinflammation. We tested the hypotheses that early caffeine and/or non-steroidal inflammatory drugs (NSAIDs) confer superior therapeutic benefits for protection against IH-induced neuroinflammation than late treatment. Newborn rats were exposed to IH or hyperoxia (50% O2) from birth (P0) to P14. For early treatment, the pups were administered: 1) daily caffeine (Caff) citrate (Cafcit, 20 mg/kg IP loading on P0, followed by 5 mg/kg from P1-P14); 2) ketorolac (Keto) topical ocular solution in both eyes from P0 to P14; 3) ibuprofen (Ibu, Neoprofen, 10 mg/kg loading dose on P0 followed by 5 mg/kg/day on P1 and P2); 4) Caff+Keto co-treatment; 5) Caff+Ibu co-treatment; or 6) equivalent volume saline (Sal). On P14, animals were placed in room air (RA) with no further treatment until P21. For late treatment, pups were exposed from P0 to P14, then placed in RA during which they received similar treatments from P15-P21 (Sal, Caff, and/or Keto), or P15-P17 (Ibu). RA controls were similarly treated. At P21, whole brains were assessed for histopathology, apoptosis, myelination, and biomarkers of inflammation. IH caused significant brain injury and hemorrhage, inflammation, reduced myelination, and apoptosis. Early treatment with Caff alone or in combination with NSAIDs conferred better neuroprotection against IH-induced damage than late treatment. Early postnatal treatment during a critical time of brain development, may be preferable for the prevention of IH-induced brain injury in preterm infants.

Executive Function Assessment in 2-Year-Olds Born Preterm

OBJECTIVE

 Our objective was to investigate the executive function and its relationship with gestational age, sex, maternal education, and neurodevelopmental outcome at 2 years corrected age in children born preterm.

METHOD

 Executive function was assessed by means of the Multisearch Multilocation Task (MSML), Reversed Categorization Task (RevCat), and Snack Delay Task (SDT). Infant and maternal characteristics were gathered from the child's record. The developmental outcome was measured by the Bayley Scales and a multidisciplinary risk evaluation for autism.

RESULTS

 The executive function battery was completed by 97 children. The majority were able to successfully complete the MSML and SDT but failed RevCat. The lower the gestational age and the maternal education, the lower the executive function scores. Better cognition and motor function, as well as low autism risk, were associated with better executive function scores. Executive function was not related to sex.

INTERPRETATION

 This cohort study provides evidence that it is feasible to assess executive function in 2-year-olds born preterm. Executive function is related to gestational age and maternal education and is positively correlated with behavioral outcome. Therefore, executive functions can be a valuable target for early intervention, resulting in improvements in neurodevelopmental outcomes in children born preterm.

Reproducibility of Diffusion MRI-Based Tractography in the Fetal Brain

BACKGROUND

Tractography based on diffusion MRI (dMRI) is a useful tool to study white matter of the developing brain. However, its application in fetal brains is limited due to motion artifacts and low resolution of in utero dMRI, leading to reduced reliability, which was scarcely investigated in previous studies.

PURPOSE

To identify reliably traceable fibers in fetal brains and assess whether reproducibility varies with gestational age (GA) and varies between brain regions.

STUDY TYPE

Prospective cohort study.

SUBJECTS

A total of 44 healthy fetuses with GAs between 25 and 37 (31 ± 6).

FIELD STRENGTH/SEQUENCE

3-T, diffusion-weighted echo-planar imaging sequence (2-5 repeated dMRI scans within the same session per subject).

ASSESSMENT

We fitted dMRI with constrained spherical deconvolution model and conducted tractography on eight fibers. We extracted volume, fractional anisotropy, and fiber count for each fiber and assessed the reproducibility of these metrics between repeated scans within each subject. Data were divided into two age-based subgroups (≤30 weeks, N = 28, and >30 weeks, N = 16) for further tests.

STATISTICAL TESTS

The reproducibility were compared between fibers by analysis of variance and two-sample t tests. Multiple comparisons were corrected by the false discovery rate (5% was accepted).

RESULTS

The reproducibility of the anterior thalamic radiation, inferior longitudinal fasciculus (ILF), genu of the corpus callosum (GCC), and body of the corpus callosum (BCC) significantly decreased with advancing GA (correlation coefficient = 0.525-0.823), as confirmed by group comparisons between fetuses in early GA (≤30 weeks) and late GA (>30 weeks) groups. Corticospinal tract, inferior fronto-occipital fasciculus, and GCC showed high reproducibility for fiber count (weighted dice average = 0.846 vs. 0.814), while BCC and ILF exhibited the lowest reproducibility in both age groups.

DATA CONCLUSION

The study indicates that the reliability of fetal brain tractography depends on GA and varies among different fibers.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.

Intestinal microbiota modulates neuroinflammatory response and brain injury after neonatal hypoxia-ischemia

Premature infants lack a normal intestinal microbial community and also at risk of perinatal hypoxic-ischemic (HI) brain injury, which is considered to be one of the major factors for motor, sensory, and cognitive deficits. We hypothesized that neonatal gut microbiota composition modulated the immune reaction and severity of neonatal H-I brain injury. Neonatal C57BL/6J mouse pups were exposed to H-I protocol consisting of permanent left carotid artery ligation, followed by 8% hypoxia for 60 min. Microbial manipulation groups included 1) antibiotic treatment, E18 (maternal) to P5; 2) antibiotic treatment E18 to P5 + E. coli gavage; 3) antibiotic treatment E18 to P5 + B. infantis gavage; and 4) saline to pups with dams getting fresh water. The extent of brain injury and recovery was measured on MRI. Edematous injury volume was significantly higher in E. coli group than that in B. infantis group and in fresh water group. Gene expression in brains of pro-inflammatory cytokines (IL1β, IL6, IL2, TNF-α and toll-like receptors 2-6) were elevated to a greater extent in the E. coli group at P10, no injury, and at P13, 72 hours after H-I relative to sham control and B. infantis groups. Significant effects of microbiome and brain injury and interaction of these factors were found in abundance of major phyla. The neuroinflammatory response and brain injury after neonatal hypoxia-ischemia are affected by intestinal microbiota, providing opportunities for therapeutic intervention through targeting the early colonization and development of the gut microbiota.

Evolution of grey matter injury over 21 days after hypoxia-ischaemia in preterm fetal sheep

Reduced grey matter volume in preterm infants is associated with later disability, but its time course and relationship with white matter injury are not well understood. We recently showed that moderate-severe hypoxia-ischaemia (HI) in preterm fetal sheep led to severe cystic injury 2-3 weeks later. In the same cohort we now show profound hippocampal neuronal loss from 3 days after HI. By contrast, reduction in cortical area and perimeter developed much more slowly, with maximum reduction at day 21. There was transient upregulation of cleaved caspase-3-positive apoptosis in the cortex at day 3 but no change in neuronal density or macroscopic injury of the cortex. Both microglia and astrocytes were transiently upregulated in the grey matter. EEG power was initially profoundly suppressed but partially recovered by 21 days of recovery, and final power was correlated with white matter area (p < 0.001, r² = 0.75, F = 24.19), cortical area (p = 0.004, r² = 0.44, F = 11.90) and hippocampi area (p = 0.049, r² = 0.23, F = 4.58). In conclusion, the present study suggests that in preterm fetal sheep, hippocampal injury is established within a few days of acute HI, but impaired cortical growth develops slowly, in a similar time course to severe white matter injury.

Preterm infant body composition, working memory, and temperament

Altered body composition in preterm infants is associated with risks to cognitive development, but the effect specific to prefrontal cortex (PFC) development is unknown. We were interested in the impact of fat mass (FM) and fat free mass (FFM) gains out to 4 months corrected gestational age (CGA) on PFC development, as indexed by working memory and temperament. This is a prospective observational pilot study recruiting 100 preterm (<33 weeks gestation), appropriate for gestational age, and very low birth weight infants, of which 49 infants met inclusion criteria. Body composition was measured using air displacement plethysmography at hospital discharge and 4 months CGA. Questionnaire based temperament assessments were completed at 12 and 24 months CGA and a working memory assessment was completed at 24 months CGA. Associations between developmental tests and body composition obtained at term and 4 months were analyzed. Increased FM at discharge was associated with increased fear and decreased soothability at 12 months. Increased FM at 4 months was associated with increased activity level, increased distress from limitations at 12 months and decreased attentional shifting, decreased frustration, and decreased inhibitory control at 24 months. Increased FFM at 4 months was associated with increased activity level at 12 months and increased impulsivity and decreased low intensity pleasure at 24 months. In this exploratory pilot study, increased FM out to 4 months and increased FFM after discharge are associated with negative markers of infant temperament. Infant temperament may be sensitive to body composition status at least to 4 months CGA.

Bifidobacterium: Host-Microbiome Interaction and Mechanism of Action in Preventing Common Gut-Microbiota-Associated Complications in Preterm Infants: A Narrative Review

The development and health of infants are intertwined with the protective and regulatory functions of different microorganisms in the gut known as the gut microbiota. Preterm infants born with an imbalanced gut microbiota are at substantial risk of several diseases including inflammatory intestinal diseases, necrotizing enterocolitis, late-onset sepsis, neurodevelopmental disorders, and allergies which can potentially persist throughout adulthood. In this review, we have evaluated the role of Bifidobacterium as commonly used probiotics in the development of gut microbiota and prevention of common diseases in preterm infants which is not fully understood yet. The application of Bifidobacterium as a therapeutical approach in the re-programming of the gut microbiota in preterm infants, the mechanisms of host-microbiome interaction, and the mechanism of action of this bacterium have also been investigated, aiming to provide new insights and opportunities in microbiome-targeted interventions in personalized medicine.

Neurocognitive outcomes at age 5 years after prophylactic hydrocortisone in infants born extremely preterm

AIM

To assess the 5-year neurocognitive outcomes of children born extremely preterm exposed to prophylactic hydrocortisone to improve survival without bronchopulmonary dysplasia.

METHOD

This was a prespecified secondary analysis of the PREMILOC clinical trial (trial registration: EudraCT no. 2007-002041-20, NCT00623740). The primary outcome was full-scale IQ based on the Wechsler Preschool and Primary Scale of Intelligence.

RESULTS

Among 109 surviving children recruited at the Robert Debré Children's Hospital, Paris, outcome data were available for 42 out of 56 infants (75%) in the group treated with hydrocortisone and 41 out of 53 (77%) in the placebo group. Mean scores were not significantly different between the two groups on full-scale IQ (hydrocortisone: 91.9 [SD = 13.9], placebo: 86.3 [SD = 15.4]; mean difference = 5.7, 95% confidence interval [CI] = -1.0 to 12.3, p = 0.10); however, working memory and retention ability were significantly better in the group treated with hydrocortisone. In a multivariate logistic regression including potential confounding variables, hydrocortisone treatment was significantly associated with a greater chance to survive at 5 years of age with a full-scale IQ equal to or greater than 90 compared to placebo (adjusted odds ratio = 4.26, 95% CI = 1.47-12.36, p = 0.008).

INTERPRETATION

This exploratory analysis provides reassuring data regarding the long-term neurodevelopmental safety of prophylactic hydrocortisone in infants born extremely preterm.

Brain MRI findings of prelingually deaf children and cochlear implant outcome: Preliminary results

OBJECTIVE

To estimate the incidence of brain abnormalities in a cohort of prelingually deaf children and whether these abnormalities can impact the hearing outcomes of patients eligible for cochlear implantation (CI).

METHODS

We performed a retrospective review of consecutive medical charts of prelingually deaf children under 12 years of age who underwent brain magnetic resonance imaging (MRI) during their preoperative workup for CI surgery. We used the category of auditory performance (CAP) test and the speech intelligibility rating (SIR) test to assess the hearing and speech performance of the children, respectively.

RESULTS

The MRIs of 285 patients, 174 boys and 111 girls with a mean age of 36.4 (±16) months, were evaluated for this study. We identified 31 patients with abnormal findings (10.88%): (17/31) (54.8%) had MRI brain abnormalities, (9/31) (29%) had inner ear anomalies, and (5/31) (16.1%) had both inner ear and brain abnormalities. The most frequent inner ear anomaly was an enlarged vestibular aqueduct, while white matter lesions were the most common brain abnormality. The CAP and SIR mean score of patients with inner ear anomalies was slightly, but not significantly, higher than those of patients with brain abnormalities.

CONCLUSION

CAP and SIR scores were not significantly different in children with brain abnormalities than inner ear anomalies. These patients can still benefit from CI to improve their overall hearing and speech performance.

MRI-based brain volumes of preterm infants at term: a systematic review and meta-analysis

BACKGROUND

MRI allows a detailed assessment of brain structures in preterm infants, outperforming cranial ultrasound. Neonatal MR-based brain volumes of preterm infants could serve as objective, quantitative and reproducible surrogate parameters of early brain development. To date, there are no reference values for preterm infants' brain volumes at term-equivalent age.

OBJECTIVE

Systematic review of the literature to determine reference ranges for MRI-based brain volumes of very preterm infants at term-equivalent age.

METHODS

PubMed Database was searched on 6 April 2020 for studies reporting MR-based brain volumes on representative unselected populations of very preterm and/or very low birthweight infants examined at term equivalent age (defined as 37-42 weeks mean postmenstrual age at MRI). Analyses were limited to volumetric parameters reported in >3 studies. Weighted mean volumes and SD were both calculated and simulated for each parameter.

RESULTS

An initial 367 publications were identified. Following application of exclusion criteria, 13 studies from eight countries were included for analysis, yielding four parameters. Weighted mean total brain volume was 379 mL (SD 72 mL; based on n=756). Cerebellar volume was 21 mL (6 mL; n=791), cortical grey matter volume 140 mL (47 mL; n=572) and weighted mean volume of unmyelinated white matter was 195 mL (38 mL; n=499).

CONCLUSION

This meta-analysis reports pooled data on several brain and cerebellar volumes which can serve as reference for future studies assessing MR-based volumetric parameters as a surrogate outcome for neurodevelopment and for the interpretation of individual or cohort MRI-based volumetric findings.

Early developmental trajectory of children with prenatal alcohol and opioid exposure

BACKGROUND

With significant increases in opioid use/misuse and persistent high prevalence of prenatal alcohol exposure (PAE), identifying infants at risk for long-term developmental sequelae due to these exposures remains an urgent need. This study reports on developmental outcomes in young children from a prospective cohort, ENRICH-1, which recruited pregnant women and followed up maternal-infant pairs.

METHODS

Subjects were assigned to four study groups based on prenatal use of medications for opioid use disorder (MOUD), PAE, MOUD+PAE, and unexposed controls (UC). Mixed effects modeling was used to evaluate changes in the Bayley Scales of Infant Development-III (BSID-III) Cognitive, Language, and Motor scores between 6 and 20 months.

RESULTS

There was a significant three-way interaction (MOUD-by-PAE-by-Time) with respect to the BSID-III Cognitive (p = 0.045) and Motor (p = 0.033) scales. Significant changes between the two evaluations were observed for MOUD group in Cognitive and Language scores; for PAE group in Cognitive, Language, and Motor scores, and for MOUD+PAE group in Language scores after adjusting for child sex and family socio-economic status. The developmental scores for the UC remained stable.

CONCLUSION

Observed decline in neurodevelopmental scores during the first 2 years of life emphasizes the importance of a longitudinal approach when evaluating children with prenatal polysubstance exposure.

IMPACT

BSID-III scores were stable during the first 2 years of life for unexposed children. BSID-III scores declined for children with prenatal exposures to alcohol and/or opioids. Standard developmental tests may not be sensitive enough during the first year of life. Findings emphasize the need for repeated evaluations of children who are at high risk.

Magnetic resonance spectroscopy brain metabolites at term and 3-year neurodevelopmental outcomes in very preterm infants

BACKGROUND

Noninvasive advanced neuroimaging and neurochemical assessment can identify subtle abnormalities and predict neurodevelopmental impairments. Our objective was to quantify white matter metabolite levels and evaluate their relationship with neurodevelopmental outcomes at age 3 years.

METHODS

Our study evaluated a longitudinal prospective cohort of very premature infants (<32 weeks gestational age) with single-voxel proton magnetic resonance spectroscopy from the centrum semiovale performed at term-equivalent age and standardized cognitive, verbal, and motor assessments at 3 years corrected age. We separately examined metabolite ratios in the left and right centrum semiovale. We also conducted an exploratory interaction analysis for high/low socioeconomic status (SES) to evaluate the relationship between metabolites and neurodevelopmental outcomes, after adjusting for confounders.

RESULTS

We found significant relationships between choline/creatine levels in the left and right centrum semiovale and motor development scores. Exploratory interaction analyses revealed that, for infants with low SES, there was a negative association between choline/creatine in the left centrum semiovale and motor assessment scores at age 3 years.

CONCLUSIONS

Brain metabolites from the centrum semiovale at term-equivalent age were associated with motor outcomes for very preterm infants at 3 years corrected age. This effect may be most pronounced for infants with low SES.

IMPACT

Motor development at 3 years corrected age for very preterm infants is inversely associated with choline neurochemistry within the centrum semiovale on magnetic resonance spectroscopy at term-equivalent age, especially in infants with low socioeconomic status. No prior studies have studied metabolites in the centrum semiovale to predict neurodevelopmental outcomes at 3 years corrected age based on high/low socioeconomic status. For very preterm infants with lower socioeconomic status, higher choline-to-creatine ratio in central white matter is associated with worse neurodevelopmental outcomes.

Associations of Macronutrient Intake Determined by Point-of-Care Human Milk Analysis with Brain Development among very Preterm Infants

Point-of-care human milk analysis is now feasible in the neonatal intensive care unit (NICU) and allows accurate measurement of macronutrient delivery. Higher macronutrient intakes over this period may promote brain growth and development. In a prospective, observational study of 55 infants born at <32 weeks’ gestation, we used a mid-infrared spectroscopy-based human milk analyzer to measure the macronutrient content in repeated samples of human milk over the NICU hospitalization. We calculated daily nutrient intakes from unfortified milk and assigned infants to quintiles based on median intakes over the hospitalization. Infants underwent brain magnetic resonance imaging at term equivalent age to quantify total and regional brain volumes and fractional anisotropy of white matter tracts. Infants in the highest quintile of energy intake from milk, as compared with the lower four quintiles, had larger total brain volume (31 cc, 95% confidence interval [CI]: 5, 56), cortical gray matter (15 cc, 95%CI: 1, 30), and white matter volume (23 cc, 95%CI: 12, 33). Higher protein intake was associated with larger total brain (36 cc, 95%CI: 7, 65), cortical gray matter (22 cc, 95%CI: 6, 38) and deep gray matter (1 cc, 95%CI: 0.1, 3) volumes. These findings suggest innovative strategies to close nutrient delivery gaps in the NICU may promote brain growth for preterm infants.

Visuospatial working memory of children and adults born very preterm and/or very low birth weight

BACKGROUND

This paper examines the visuospatial working memory (WM) performance of children and adults born very preterm (VPT) and/or very low birth weight (VLBW) relative to their full-term (FT)-born peers. Of interest was the nature and severity of observed impairments, as well associations with educational/occupational functioning at each age point.

METHODS

Participants were drawn from two prospective cohort studies: (1) a regional cohort of 110 VPT (<32 weeks' gestation and <1500 g) and 113 FT born children assessed at age 12 years; (2) a national cohort of 229 VLBW (<1500 g) and 100 FT born adults assessed at age 28 years. Visuospatial WM was assessed using a four-span/difficulty-level computerized task.

RESULTS

Both children and adults born VPT/VLBW had poorer visuospatial WM than FT controls, with their performance less accurate, slower (correct trials), and less efficient with increasing task difficulty (Cohen's d = 0.27-0.51; p < 0.05). Adults had better visuospatial WM than children, but between-group differences were highly similar across ages, before and after adjustment for confounding social background and individual factors. Poorer WM was associated with lower levels of educational and occupational/socioeconomic achievement.

CONCLUSIONS

Visuospatial WM difficulties persist into adulthood raising concerns for the longer-term cognitive and adaptive functioning of VPT survivors.

IMPACT

Both children and adults born very preterm have poorer visuospatial working memory than their term-born peers. They are less accurate, take longer to respond correctly and are less efficient, with test performance declining with increasing cognitive demand. Similar differences in visuospatial working memory are observed between VPT/VLBW and full-term individuals during both childhood and adulthood, with these differences remaining even after covariate adjustment. Individuals with poorer visuospatial working memory have lower levels of educational achievement and occupational/socioeconomic success. Visuospatial working memory difficulties persist into adulthood and appear to continue to impact everyday functioning and life-course opportunities.

Brain proton magnetic resonance spectroscopy and neurodevelopment after preterm birth: a systematic review

BACKGROUND

Preterm infants are at risk of neurodevelopmental impairments. At present, proton magnetic resonance spectroscopy (¹H-MRS) is used to evaluate brain metabolites in asphyxiated term infants. The aim of this review is to assess associations between cerebral ¹H-MRS and neurodevelopment after preterm birth.

METHODS

PubMed and Embase were searched to identify studies using ¹H-MRS and preterm birth. Eligible studies for this review included ¹H-MRS of the brain, gestational age ≤32 weeks, and neurodevelopment assessed at a corrected age (CA) of at least 12 months up to the age of 18 years.

RESULTS

Twenty papers evaluated ¹H-MRS in preterm infants at an age between near-term and 18 years and neurodevelopment. ¹H-MRS was performed in both white (WM) and gray matter (GM) in 12 of 20 studies. The main regions were frontal and parietal lobe for WM and basal ganglia for GM. N-acetylaspartate/choline (NAA/Cho) measured in WM and/or GM is the most common metabolite ratio associated with motor, language, and cognitive outcome at 18-24 months CA.

CONCLUSIONS

NAA/Cho in WM assessed at term-equivalent age was associated with motor, cognitive, and language outcome, and NAA/Cho in deep GM was associated with language outcome at 18-24 months CA.

IMPACT

In preterm born infants, brain metabolism assessed using ¹H-MRS at term-equivalent age is associated with motor, cognitive, and language outcomes at 18-24 months. ¹H-MRS at term-equivalent age in preterm born infants may be used as an early indication of brain development. Specific findings relating to NAA were most predictive of outcome.

Early preterm infant microbiome impacts adult learning

Interventions to mitigate long-term neurodevelopmental deficits such as memory and learning impairment in preterm infants are warranted. Manipulation of the gut microbiome affects host behaviors. In this study we determined whether early maturation of the infant microbiome is associated with neurodevelopment outcomes. Germ free mice colonized at birth with human preterm infant microbiomes from infants of advancing post menstrual age (PMA) demonstrated an increase in bacterial diversity and a shift in dominance of taxa mimicking the human preterm microbiome development pattern. These characteristics along with changes in a number of metabolites as the microbiome matured influenced associative learning and memory but not locomotor ability, anxiety-like behaviors, or social interaction in adult mice. As a regulator of learning and memory, brain glial cell-derived neurotrophic factor increased with advancing PMA and was also associated with better performance in associative learning and memory in adult mice. We conclude that maturation of the microbiome in early life of preterm infants primes adult associative memory and learning ability. Our findings suggest a critical window of early intervention to affect maturation of the preterm infant microbiome and ultimately improve neurodevelopmental outcomes.

Oral language of school-aged children born pretermaturely: a population-based analysis from Madeira Island, Portugal

Premature birth and low birth weight are very important factors in neurodevelopment. Current research in this population focuses on children born prematurely, with no underlying complications in the post-natal period, who are likely to develop specific disorders with their language development and consequently with their learning capabilities too. This study aims to analyse the oral language skills of prematurely born children in comparison to their school-aged peers. The children were assessed in the respective schools, 27 preterm children (16 under 32 weeks and 11 with 32 or more weeks of gestation) and 49 term paired by gender, age, and school year. Tests including simple and complex structures for assessing semantics, morphosyntax, and phonology were used, as well as a test of verbal memory. Preterm born children, regardless of their prematurity grade, showed significantly lower results than their peers, and more than a half of them, 52%, presented low scores in all language tests simultaneously, showing an important language deficit. In contrast, in the term born children group only 14% showed low scores simultaneously in all tests. Verbal memory ability proved to be lower than that of their term peers, regardless of the gestational age and birth weight of preterm children. As a result of this analysis we consider that the evaluation of the linguistic development of these children, even in cases of moderate to late prematurity, should be monitored in order to identify earlier the existence of deficits and prevent psychosocial and learning problems.

Association between Term Equivalent Brain Magnetic Resonance Imaging and 2-Year Outcomes in Extremely Preterm Infants: A Report from the Preterm Erythropoietin Neuroprotection Trial Cohort

OBJECTIVES

To compare the term equivalent brain magnetic resonance imaging (MRI) findings between erythropoietin (Epo) treated and placebo control groups in infants 24^0/7-27^6/7 weeks of gestational age and to assess the associations between MRI findings and neurodevelopmental outcomes at 2 years corrected age.

STUDY DESIGN

The association between brain abnormality scores and Bayley Scales of Infant Development, Third Edition at 2 years corrected age was explored in a subset of infants enrolled in the Preterm Erythropoietin Neuroprotection Trial. Potential risk factors for neurodevelopmental outcomes such as treatment assignment, recruitment site, gestational age, inpatient complications, and treatments were examined using generalized estimating equation models.

RESULTS

One hundred ten infants were assigned to Epo and 110 to placebo groups. 27% of MRI scans were rated as normal, and 60%, 10%, and 2% were rated as having mild, moderate, or severe abnormality. Brain abnormality scores did not significantly differ between the treatment groups. Factors that increased the risk of higher brain injury scores included intubation; bronchopulmonary dysplasia; retinopathy of prematurity; opioid, benzodiazepine, or antibiotic treatment >7 days; and periventricular leukomalacia or severe intraventricular hemorrhage diagnosed on cranial ultrasound. Increased global brain abnormality and white matter injury scores at term equivalent were associated with reductions in cognitive, motor, and language abilities at 2 years of corrected age.

CONCLUSIONS

Evidence of brain injury on brain MRIs obtained at term equivalent correlated with adverse neurodevelopmental outcomes as assessed by the Bayley Scales of Infant and Toddler Development, Third Edition at 2 years corrected age. Early Epo treatment had no effect on the MRI brain injury scores compared with the placebo group.

Cortical Synaptic Reorganization Under Chronic Arsenic Exposure

There is solid epidemiological evidence that arsenic exposure leads to cognitive impairment, while experimental work supports the hypothesis that it also contributes to neurodegeneration. Energy deficit, oxidative stress, demyelination, and defective neurotransmission are demonstrated arsenic effects, but it remains unclear whether synaptic structure is also affected. Employing both a triple-transgenic Alzheimer's disease model and Wistar rats, the cortical microstructure and synapses were analyzed under chronic arsenic exposure. Male animals were studied at 2 and 4 months of age, after exposure to 3 ppm sodium arsenite in drinking water during gestation, lactation, and postnatal development. Through nuclear magnetic resonance, diffusion-weighted images were acquired and anisotropy (integrity; FA) and apparent diffusion coefficient (dispersion degree; ADC) metrics were derived. Postsynaptic density protein and synaptophysin were analyzed by means of immunoblot and immunohistochemistry, while dendritic spine density and morphology of cortical pyramidal neurons were quantified after Golgi staining. A structural reorganization of the cortex was evidenced through high-ADC and low-FA values in the exposed group. Similar changes in synaptic protein levels in the 2 models suggest a decreased synaptic connectivity at 4 months of age. An abnormal dendritic arborization was observed at 4 months of age, after increased spine density at 2 months. These findings demonstrate alterations of cortical synaptic connectivity and microstructure associated to arsenic exposure appearing in young rodents and adults, and these subtle and non-adaptive plastic changes in dendritic spines and in synaptic markers may further progress to the degeneration observed at older ages.

Heterogeneity of the attentional system's efficiency among very prematurely born pre-schoolers

Very preterm birth increases the risk of ADHD as well as other neurodevelopmental disorders. Deficits within the attentional system were previously signaled in preterm children; however, studies lacked in consideration of an intragroup differentiation. Thus, this study aimed to verify whether deficits in the attentional mechanisms are inter-individually differentiated among very prematurely born children and if so, which biomedical and non-biomedical factors are associated with the profile of deficits within the attentional system. We tested the efficiency of attentional processes among 5-year-old children with the Attention Network Task - Child Version. The results have indicated that 26% of very preterm children presented with the suboptimal functioning of the attentional system (more than 1 SD below mean score of full-term children in attentional alerting and orienting), whereas 74% were characterized by the normal efficiency of attention. The profile of attentional deficits observed among very preterm preschoolers was associated with significantly lower birth weight and decreased family living standard. Very prematurely born children are thus a relatively heterogeneous group in terms of the efficiency of attentional system and deficits apply to only some of those children. Early developmental support aimed at enhancing attentional functioning should be addressed to children with lower birth weight in the first place.

The impact of preterm birth on the executive functioning of preschool children: A systematic review

This paper presents a systematic review of the impact of preterm childbirth on the later executive functioning of preschool-aged children. A systematic search for studies published between 2014 and 2019 was performed using the following keywords: executive funct* AND preterm AND child. The methodological quality of the reports was examined using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Thirty-two studies were reviewed and scored at least 67% on the methodological quality assessment. In comparison to children born full-term, preschool children born preterm exhibit executive functioning deficits in the dimensions of the global index, inhibitory control, cognitive flexibility, working memory, and planning/executive functioning. These findings are independent of the degree of prematurity at birth. Since executive functioning has many complex components, future studies should assess the dimensions of executive functioning separately in preschool-aged children born preterm, rather than as a single measure.

Development of human white matter pathways in utero over the second and third trimester

During the second and third trimesters of human gestation, rapid neurodevelopment is underpinned by fundamental processes including neuronal migration, cellular organization, cortical layering, and myelination. In this time, white matter growth and maturation lay the foundation for an efficient network of structural connections. Detailed knowledge about this developmental trajectory in the healthy human fetal brain is limited, in part, due to the inherent challenges of acquiring high-quality MRI data from this population. Here, we use state-of-the-art high-resolution multishell motion-corrected diffusion-weighted MRI (dMRI), collected as part of the developing Human Connectome Project (dHCP), to characterize the in utero maturation of white matter microstructure in 113 fetuses aged 22 to 37 wk gestation. We define five major white matter bundles and characterize their microstructural features using both traditional diffusion tensor and multishell multitissue models. We found unique maturational trends in thalamocortical fibers compared with association tracts and identified different maturational trends within specific sections of the corpus callosum. While linear maturational increases in fractional anisotropy were seen in the splenium of the corpus callosum, complex nonlinear trends were seen in the majority of other white matter tracts, with an initial decrease in fractional anisotropy in early gestation followed by a later increase. The latter is of particular interest as it differs markedly from the trends previously described in ex utero preterm infants, suggesting that this normative fetal data can provide significant insights into the abnormalities in connectivity which underlie the neurodevelopmental impairments associated with preterm birth.

Structural Changes in the Cortico-Ponto-Cerebellar Axis at Birth are Associated with Abnormal Neurological Outcomes in Childhood

White matter lesions in hypoxic-ischemic encephalopathy (HIE) are considered to be the important substrate of frequent neurological consequences in preterm infants. The aim of the study was to analyze volumes and tractographic parameters of the cortico-ponto-cerebellar axis to assess alterations in the periventricular fiber system and crossroads, corticopontine and corticospinal pathways and prospective transsynaptic changes of the cerebellum.Term infants (control), premature infants without (normotypic) and with perinatal HIE (HIE) underwent brain magnetic resonance imaging at term-equivalent age (TEA) and at 2 years. Cerebrum, cerebellum, brainstem divisions and ventrodorsal compartments volumetric analysis were performed, as well as fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of corticopontine, corticospinal pathways and middle cerebellar peduncles. Amiel-Tison scale at TEA and the Hempel test at 2 years were assessed.Cerebellum, brainstem and its compartments volumes were decreased in normotypic and HIE groups at TEA, while at 2 years volumes were significantly reduced in the HIE group, accompanied by decreased volume and FA and increased ADC of corticopontine and corticospinal pathways. Negative association of the brainstem, cerebellum, mesencephalon, pons, corticopontine volumes and corticospinal pathway FA at TEA with the neurological score at 2 years. Cerebellum and pons volumes presented as potential prognostic indicators of neurological outcomes.Our findings agree that these pathways, as a part of the periventricular fiber system and crossroads, exhibit lesion-induced reaction and vulnerability in HIE. Structural differences between normotypic and HIE group at the 2 years suggest a different developmental structural plasticity.

Anti-Inflammatory Therapies for Treatment of Inflammation-Related Preterm Brain Injury

Despite the prevalence of preterm brain injury, there are no established neuroprotective strategies to prevent or alleviate mild-to-moderate inflammation-related brain injury. Perinatal infection and inflammation have been shown to trigger acute neuroinflammation, including proinflammatory cytokine release and gliosis, which are associated with acute and chronic disturbances in brain cell survival and maturation. These findings suggest the hypothesis that the inhibition of peripheral immune responses following infection or nonspecific inflammation may be a therapeutic strategy to reduce the associated brain injury and neurobehavioral deficits. This review provides an overview of the neonatal immunity, neuroinflammation, and mechanisms of inflammation-related brain injury in preterm infants and explores the safety and efficacy of anti-inflammatory agents as potentially neurotherapeutics.

Cost burden and net monetary benefit loss of neonatal hypoglycaemia

BACKGROUND

Neonatal hypoglycaemia is a common but treatable metabolic disorder that affects newborn infants and which, if not identified and treated adequately, may result in neurological sequelae that persist for the lifetime of the patient. The long-term financial and quality-of-life burden of neonatal hypoglycaemia has not been previously examined.

METHODS

We assessed the postnatal hospital and long-term costs associated with neonatal hypoglycaemia over 80 year and 18 year time horizons, using a health-system perspective and assessing impact on quality of life using quality-adjusted life year (QALYs). A decision analytic model was used to represent key outcomes in the presence and absence of neonatal hypoglycaemia.

RESULTS

The chance of developing one of the outcomes of neonatal hypoglycaemia in our model (cerebral palsy, learning disabilities, seizures, vision disorders) was 24.03% in subjects who experienced neonatal hypoglycaemia and 3.56% in those who do did not. Over an 80 year time horizon a subject who experienced neonatal hypoglycaemia had a combined hospital and post-discharge cost of NZ$72,000 due to the outcomes modelled, which is NZ$66,000 greater than a subject without neonatal hypoglycaemia. The net monetary benefit lost due to neonatal hypoglycaemia, using a value per QALY of NZ$43,000, is NZ$180,000 over an 80 year time horizon.

CONCLUSIONS

Even under the most conservative of estimates, neonatal hypoglycaemia contributes a significant financial burden to the health system both during childhood and over a lifetime. The combination of direct costs and loss of quality of life due to neonatal hypoglycaemia means that this condition warrants further research to focus on prevention and effective treatment.

Effects of Juvenile or Adolescent Working Memory Experience and Inter-Alpha Inhibitor Protein Treatment after Neonatal Hypoxia-Ischemia

Hypoxic-Ischemic (HI) brain injury in the neonate contributes to life-long cognitive impairment. Early diagnosis and therapeutic interventions are critical but limited. We previously reported in a rat model of HI two interventional approaches that improve cognitive and sensory function: administration of Inter-alpha Inhibitor Proteins (IAIPs) and early experience in an eight-arm radial water maze (RWM) task. Here, we expanded these studies to examine the combined effects of IAIPs and multiple weeks of RWM assessment beginning with juvenile or adolescent rats to evaluate optimal age windows for behavioral interventions. Subjects were divided into treatment groups; HI with vehicle, sham surgery with vehicle, and HI with IAIPs, and received either juvenile (P31 initiation) or adolescent (P52 initiation) RWM testing, followed by adult retesting. Error rates on the RWM decreased across weeks for all conditions. Whereas, HI injury impaired global performance as compared to shams. IAIP-treated HI subjects tested as juveniles made fewer errors as compared to their untreated HI counterparts. The juvenile group made significantly fewer errors on moderate demand trials and showed improved retention as compared to the adolescent group during the first week of adult retesting. Together, results support and extend our previous findings that combining behavioral and anti-inflammatory interventions in the presence of HI improves subsequent learning performance. Results further indicate sensitive periods for behavioral interventions to improve cognitive outcomes. Specifically, early life cognitive experience can improve long-term learning performance even in the presence of HI injury. Results from this study provide insight into typical brain development and the impact of developmentally targeted therapeutics and task-specific experience on subsequent cognitive processing.

Development of visuospatial memory in preterm infants: A new paradigm to assess short-term and working memory

Preterm infants have a higher risk of showing visuospatial memory impairment, the function that allows to encode and remember visual and spatial information. It has been studied in late childhood in preterm children. Studies on visuospatial memory throughout the first 2 years of life are still scarce. Behavior, temperament, and overall cognition could be altered in preterm children affecting memory performance. Therefore, the main aim of this study was to evaluate short-term and visuospatial working memory performance in a preterm sample followed longitudinally at 12, 15, 18, and 22 months (N = 15), and compare their performance with that of full-term children (N = 65). The secondary aim was to analyze the course of mnesic development in preterm infants and relate their memory performance to other cognitive abilities and behavioral tendencies. Assessment included previously published tasks and an experimental paradigm. Results showed that preterm children scored lower than full-term children on visuospatial short-term and working memory at 12 and 22 months of age, although these results varied depending on the memory test used. Preterm children's memory results showed that these skills improve in this population between the first and second year of life. Finally, memory performance was directly associated with the level of cognitive development and the presence of proactive behaviors, while being inversely correlated with the presence of disruptive behaviors and a difficult temperamental style. These preliminary findings suggest that it is possible to detect visuospatial memory difficulties in the preterm population before the age of two.

Cost-Utility Analysis of Prophylactic Dextrose Gel vs Standard Care for Neonatal Hypoglycemia in At-Risk Infants

OBJECTIVE

To evaluate the long-term costs and impact on quality of life of using prophylactic dextrose gel in patients at increased risk of developing neonatal hypoglycemia.

STUDY DESIGN

A cost-utility analysis was performed from the perspective of the health system, using a decision tree to model the long-term clinical outcomes of neonatal hypoglycemia, including cerebral palsy, epilepsy, vision disturbances, and learning disabilities, in patients at increased risk of neonatal hypoglycemia who received prophylactic dextrose gel vs standard care. Model parameters including likelihoods of hypoglycemia and admission to a neonatal intensive care unit, were based on the pre-Hypoglycemia Prevention with Oral Dextrose Study. Estimations of the likelihood of long-term condition(s), and their costs, were based on review of published literature.

RESULTS

Patients who received prophylactic dextrose gel incurred costs to the health system of around US $14 000 over an 18-year time horizon, accruing 11.25 quality-adjusted life-years, whereas those who did not receive prophylactic treatment incurred cost of around $16 000 and experienced a utility of 11.10 quality-adjusted life-years.

CONCLUSIONS

A prophylactic strategy of using dextrose gel in infants at increased risk of neonatal hypoglycemia is likely to be cost effective compared with standard care, to reduce the direct costs to the health system over an 18-year time horizon, and improve quality of life.

Regional brain volumes, microstructure and neurodevelopment in moderate-late preterm children

OBJECTIVE

To explore whether regional brain volume and white matter microstructure at term-equivalent age (TEA) are associated with development at 2 years of age in children born moderate-late preterm (MLPT).

STUDY DESIGN

A cohort of MLPT infants had brain MRI at approximately TEA (38-44 weeks' postmenstrual age) and had a developmental assessment (Bayley Scales of Infant and Toddler Development and Infant Toddler Social Emotional Assessment) at 2 years' corrected age. Relationships between cortical grey matter and white matter volumes and 2-year developmental outcomes were explored using voxel-based morphometry. Relationships between diffusion tensor measures of white matter microstructure (fractional anisotropy (FA) and axial (AD), radial (RD) and mean (MD) diffusivities) and 2-year developmental outcomes were explored using tract-based spatial statistics.

RESULTS

189 MLPT children had data from at least one MRI modality (volumetric or diffusion) and data for at least one developmental domain. Larger cortical grey and white matter volumes in many brain regions, and higher FA and lower AD, RD and MD in several major white matter regions, were associated with better cognitive and language scores. There was little evidence that cortical grey matter and white matter volumes and white matter microstructure were associated with motor and behavioural outcomes.

CONCLUSIONS

Regional cortical grey matter and white matter volumes and white matter microstructure are associated with cognitive and language development at 2 years of age in MLPT children. Thus, early alterations to brain volumes and microstructure may contribute to some of the developmental deficits described in MLPT children.

Investigating altered brain development in infants with congenital heart disease using tensor-based morphometry

Magnetic resonance (MR) imaging studies have demonstrated reduced global and regional brain volumes in infants with congenital heart disease (CHD). This study aimed to provide a more detailed evaluation of altered structural brain development in newborn infants with CHD compared to healthy controls using tensor-based morphometry (TBM). We compared brain development in 64 infants with CHD to 192 age- and sex-matched healthy controls. T2-weighted MR images obtained prior to surgery were analysed to compare voxel-wise differences in structure across the whole brain between groups. Cerebral oxygen delivery (CDO₂) was measured in infants with CHD (n = 49) using phase contrast MR imaging and the relationship between CDO₂ and voxel-wise brain structure was assessed using TBM. After correcting for global scaling differences, clusters of significant volume reduction in infants with CHD were demonstrated bilaterally within the basal ganglia, thalami, corpus callosum, occipital, temporal, parietal and frontal lobes, and right hippocampus (p < 0.025 after family-wise error correction). Clusters of significant volume expansion in infants with CHD were identified in cerebrospinal fluid spaces (p < 0.025). After correcting for global brain size, there was no significant association between voxel-wise brain structure and CDO₂. This study localizes abnormal brain development in infants with CHD, identifying areas of particular vulnerability.

Prophylactic hydrocortisone in extremely preterm infants and brain MRI abnormality

OBJECTIVE

To determine whether early low-dose hydrocortisone treatment in extremely preterm infants is associated with brain damage assessed by MRI at term equivalent of age (TEA).

PATIENTS AND OUTCOMES

This is a predefined secondary analysis of brain abnormalities, observed by MRI at TEA, of patients randomly assigned to receive either placebo or hydrocortisone in the PREMILOC trial. Outcomes were based on brain abnormalities graded according to Kidokoro scores.

RESULTS

Among 412 survivors at TEA, 300 MRIs were performed and 295 were suitable for analysis. Kidokoro scoring was completed for 119/148 and 110/147 MRIs in the hydrocortisone and placebo groups, respectively. The distribution of the Kidokoro white matter (WM) subscore and other subscores was not significantly different between the two groups. There was, however, a significant association between a higher overall Kidokoro score and hydrocortisone treatment (5.84 (SD 3.51) for hydrocortisone and 4.98 (SD 2.52) for placebo; mean difference, 0.86; 95% CI 0.06 to 1.66; p=0.04). However, hydrocortisone was not statistically associated with moderate-to-severe brain lesions (Kidokoro overall score ≥6) in a multivariate logistic regression model accounting for potential confounding variables (adjusted OR (95% CI) 1.27 (0.75 to 2.14), p=0.38). Bronchopulmonary dysplasia at 36 weeks postmenstrual age significantly predicted both WM damage (adjusted OR (95% CI) 2.70 (1.03 to 7.14), p=0.04) and global brain damage (adjusted OR (95% CI) 2.18 (1.19 to 3.99), p=0.01).

CONCLUSIONS

Early hydrocortisone exposure in extremely preterm infants is not statistically associated with either WM brain damage or overall moderate-to-severe brain lesions when adjusted for other neonatal variables.

TRIAL REGISTRATION NUMBER

EudraCT number 2007-002041-20, NCT00623740.

Retinopathy of Prematurity and Bronchopulmonary Dysplasia are Independent Antecedents of Cortical Maturational Abnormalities in Very Preterm Infants

Very preterm (VPT) infants are at high-risk for neurodevelopmental impairments, however there are few validated biomarkers at term-equivalent age that accurately measure abnormal brain development and predict future impairments. Our objectives were to quantify and contrast cortical features between full-term and VPT infants at term and to associate two key antecedent risk factors, bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP), with cortical maturational changes in VPT infants. We prospectively enrolled a population-based cohort of 110 VPT infants (gestational age ≤31 weeks) and 51 healthy full-term infants (gestational age 38-42 weeks). Structural brain MRI was performed at term. 94 VPT infants and 46 full-term infants with high-quality T2-weighted MRI were analyzed. As compared to full-term infants, VPT infants exhibited significant global cortical maturational abnormalities, including reduced surface area (-5.9%) and gyrification (-6.7%) and increased curvature (5.9%). In multivariable regression controlled for important covariates, BPD was significantly negatively correlated with lobar and global cortical surface area and ROP was significantly negatively correlated with lobar and global sulcal depth in VPT infants. Our cohort of VPT infants exhibited widespread cortical maturation abnormalities by term-equivalent age that were in part anteceded by two of the most potent neonatal diseases, BPD and ROP.

Spectral slowing is associated with working memory performance in children born very preterm

Children born very preterm (VPT) often demonstrate selective difficulties in working memory (WM), which may underlie academic difficulties observed in this population. Despite this, few studies have investigated the functional networks underlying WM in young children born VPT, a period when cognitive deficits become apparent. Using magnetoencephalography, we examined the networks underlying the maintenance of visual information in 6-year-old VPT (n = 15) and full-term (FT; n = 20) children. Although task performance was similar, VPT children engaged different oscillatory mechanisms during WM maintenance. Within the FT group, we observed higher mean whole-brain connectivity in the alpha-band during the retention (i.e. maintenance) interval associated with correct compared to incorrect responses. VPT children showed reduced whole-brain alpha synchrony, and a different network organization with fewer connections. In the theta-band, VPT children demonstrated a slight increase in whole-brain connectivity during WM maintenance, and engaged similar network hubs as FT children in the alpha-band, including the left dorsolateral prefrontal cortex and superior temporal gyrus. These findings suggest that VPT children rely on the theta-band to support similar task performance. Altered oscillatory mechanisms may reflect a less mature pattern of functional recruitment underlying WM in VPT children, which may affect the processing in complex ecological situations.

The Influence of Early Nutrition on Brain Growth and Neurodevelopment in Extremely Preterm Babies: A Narrative Review

Extremely preterm babies are at increased risk of less than optimal neurodevelopment compared with their term-born counterparts. Optimising nutrition is a promising avenue to mitigate the adverse neurodevelopmental consequences of preterm birth. In this narrative review, we summarize current knowledge on how nutrition, and in particular, protein intake, affects neurodevelopment in extremely preterm babies. Observational studies consistently report that higher intravenous and enteral protein intakes are associated with improved growth and possibly neurodevelopment, but differences in methodologies and combinations of intravenous and enteral nutrition strategies make it difficult to determine the effects of each intervention. Unfortunately, there are few randomized controlled trials of nutrition in this population conducted to determine neurodevelopmental outcomes. Substantial variation in reporting of trials, both of nutritional intakes and of outcomes, limits conclusions from meta-analyses. Future studies to determine the effects of nutritional intakes in extremely preterm babies need to be adequately powered to assess neurodevelopmental outcomes separately in boys and girls, and designed to address the many potential confounders which may have clouded research findings to date. The development of minimal reporting sets and core outcome sets for nutrition research will aid future meta-analyses.

Impaired structural connectivity between dorsal attention network and pulvinar mediates the impact of premature birth on adult visual-spatial abilities

The dorsal attention network (DAN), including frontal eye fields and posterior parietal cortices, and its link with the posterior thalamus, contribute to visual-spatial abilities. Very premature birth impairs both visual-spatial abilities and cortico-thalamic structural connectivity. We hypothesized that impaired structural DAN-pulvinar connectivity mediates the effect of very premature birth on adult visual-spatial abilities. Seventy very premature (median age 26.6 years) and 57 mature born adults (median age 26.6 years) were assessed with cognitive tests and diffusion tensor imaging. Perceptual organization (PO) index of the Wechsler Adult Intelligence Scale-III was used as a proxy for visual-spatial abilities, and connection probability maps in the thalamus, derived from probabilistic tractography from the DAN, were used as a proxy for DAN-thalamic connectivity. Premature born adults showed decreases in both PO-index and connection probability from DAN into the pulvinar, with both changes being positively correlated. Moreover, path analysis revealed that DAN-pulvinar connectivity mediates the relationship between very premature birth and PO-index. Results provide evidence for long-term effects of very premature birth on structural DAN-pulvinar connectivity, mediating the effect of prematurity on adult visual-spatial impairments. Data suggest DAN-pulvinar connectivity as a specific target of prognostic and diagnostic procedures for visual-spatial abilities after premature birth.

Clemastine rescues myelination defects and promotes functional recovery in hypoxic brain injury

Hypoxia can injure brain white matter tracts, comprised of axons and myelinating oligodendrocytes, leading to cerebral palsy in neonates and delayed post-hypoxic leukoencephalopathy (DPHL) in adults. In these conditions, white matter injury can be followed by myelin regeneration, but myelination often fails and is a significant contributor to fixed demyelinated lesions, with ensuing permanent neurological injury. Non-myelinating oligodendrocyte precursor cells are often found in lesions in plentiful numbers, but fail to mature, suggesting oligodendrocyte precursor cell differentiation arrest as a critical contributor to failed myelination in hypoxia. We report a case of an adult patient who developed the rare condition DPHL and made a nearly complete recovery in the setting of treatment with clemastine, a widely available antihistamine that in preclinical models promotes oligodendrocyte precursor cell differentiation. This suggested possible therapeutic benefit in the more clinically prevalent hypoxic injury of newborns, and we demonstrate in murine neonatal hypoxic injury that clemastine dramatically promotes oligodendrocyte precursor cell differentiation, myelination, and improves functional recovery. We show that its effect in hypoxia is oligodendroglial specific via an effect on the M1 muscarinic receptor on oligodendrocyte precursor cells. We propose clemastine as a potential therapy for hypoxic brain injuries associated with white matter injury and oligodendrocyte precursor cell maturation arrest.

Development of executive functions from childhood to adolescence in very preterm-born individuals - A longitudinal study

Preterm-born individuals are at risk for poorer executive functions. Longitudinal studies investigating whether preterm-born individuals present persistent cognitive deficits, or a transient delay of development are scarce. We assessed developmental trajectories of executive functions (inhibition, working memory, cognitive flexibility) in 29 very preterm-born individuals (<32 weeks' gestation) and 25 term-born controls longitudinally over two time points, namely in childhood (7-12 years of age, TP1) and adolescence (13-16 years of age, TP2). Individual changes in executive functions were examined using relative difference scores (TP2 - TP1) / TP1). There was a significantly stronger improvement of inhibition (U = 477, p = .024) and cognitive flexibility (U = 312, p = .029) between childhood and adolescence in very preterm-born individuals than in term-born controls. Preterm-born individuals improved their performance in the domain of cognitive flexibility significantly more often (76%) between childhood and adolescence than controls (31%, χ² = 8.6, p = .003). Controls worsened significantly more often (36%) in the domain of inhibition than the preterm group (14%, χ² = 4.8, p = .028). Results indicate that healthy preterm-born individuals show prolonged development of executive functions throughout childhood up into adolescence.

Neurodevelopmental outcomes of the late preterm infant

Late preterm infants (born at 34^0/7-36^6/7 weeks gestation) have been found to have increased morbidity and mortality compared to full term infants. Research has also been done to explore longer-term neurodevelopmental outcomes. This review details neurodevelopmental outcomes from birth to adulthood for late preterm infants. Outcome studies indicate that they are at increased risk of developmental disability, school failure, behavior problems, social and medical disabilities, and death. Many questions still remain regarding late preterm infant neurodevelopmental outcomes and future research should be done into this topic. Given the high prevalence of late preterm births, even small differences in abilities, special education, and length of education may have broader consequences.

Executive Function in Relation to White Matter in Preterm and Full Term Children

Background: Executive function (EF) refers to cognitive abilities used to guide goal-directed behavior. Diffusion Tensor Imaging (DTI) provides quantitative characterization of white matter tracts in the brain. Children with preterm birth often have EF impairments and white matter injury. Aim: To examine the degree of association between EF scores and white matter fractional anisotropy (FA) as measured by DTI in children born preterm and term Study design: Cross-sectional study Subjects: Participants, 9-16 years of age, born preterm (n = 25; mean gestational age 28.6 weeks; mean birth weight 1,191 grams), and full term (n = 20) Outcome measures: White matter FA analyzed with Tract-Based Spatial Statistics, a technique that generates a skeleton representing the core of white matter tracts throughout the brain. Behavioral scores from EF tasks examining working memory, spatial memory capacity, and multiple skills from the Stockings of Cambridge. Results: The groups performed comparably on all tasks. In both groups, unfavorable working memory strategy scores were associated with lower FA. Other measures of EF were not associated with whole skeleton FA in either group in either direction. Conclusions: Strategy score on a spatial working memory task was associated with FA in preterm and full term children, suggesting common underlying neurobiology in both groups. Associations were found in frontal-parietal connections and other major tracts. Lack of associations between other EF tasks and FA may be due to variation in how children accomplish these EF tasks. Future research is required to fully understand the neurobiology of EF in children born preterm.

Connection between gut microbiome and brain development in preterm infants

Dysbiosis of the gut microbiome in preterm infants predisposes the neonate to various major morbidities including neonatal necrotizing enterocolitis and sepsis in the neonatal intensive care unit, and adverse neurological outcomes later in life. There are parallel early developmental windows for the gut microbiota and the nervous system during prenatal to postnatal of life. Therefore, preterm infants represent a unique population in which optimization of initial colonization and microbiota development can affect brain development and enhance neurological outcomes. In this review, we will first discuss the factors affecting the assembly of neonatal gut microbiota and the contribution of dysbiosis in preterm infants to neuroinflammation and neurodevelopmental disorders. We then will discuss the emerging pathways connecting the gut microbiome and brain development. Further we will discuss the significance of current models for alteration of the gut microbiome (including humanized gnotobiotic models and exposure to antibiotics) to brain development and functions. Understanding the role of early optimization of the microbiome in brain development is of paramount importance for developing microbiome-targeted therapies and protecting infants from prematurity-related neurodevelopmental diseases.

Preterm neuroimaging and neurodevelopmental outcome: a focus on intraventricular hemorrhage, post-hemorrhagic hydrocephalus, and associated brain injury

Intraventricular hemorrhage in the setting of prematurity remains the most common cause of acquired hydrocephalus. Neonates with progressive post-hemorrhagic hydrocephalus are at risk for adverse neurodevelopmental outcomes. The goal of this review is to describe the distinct and often overlapping types of brain injury in the preterm neonate, with a focus on neonatal hydrocephalus, and to connect injury on imaging to neurodevelopmental outcome risk. Head ultrasound and magnetic resonance imaging findings are described separately. The current state of the literature is imprecise and we end the review with recommendations for future radiologic and neurodevelopmental research.

Neuroimaging for Neurodevelopmental Prognostication in High-Risk Neonates

Predicting neurodevelopmental outcomes in high-risk neonates remains challenging despite advances in neonatal care. Early and accurate characterization of infants at risk for neurodevelopmental delays is necessary to best identify those who may benefit from existing early interventions and novel therapies that become available. Although neuroimaging is a promising biomarker in the prediction of neurodevelopmental outcomes in high-risk infants, it requires additional resources and expertise. Despite many advances in neonatal neuroimaging, there remain limitations in relating early neuroimaging findings with long-term outcomes; further studies are necessary to determine the optimal protocols to best identify high-risk patients and improve neurodevelopmental outcome prediction.

Effects of leptin on neurocognitive and motor functions in juvenile rats in a preterm brain damage model

Preterm infants face lifelong disabilities, including learning disorders, as well as visual, auditory and behavioral problems. Recent studies have demonstrated that leptin, an adipocytokine encoded by a gene associated with obesity and expressed in adipose tissue, affects neurocognitive and motor function; however, the mechanisms of brain damage in preterm infants are unclear. In the present study, the neuroprotective effects of leptin in a rat model of preterm hypoxic‑ischemic brain damage were investigated. Rats (2‑days‑old) were subjected to brain damage (ligation of the common carotid artery followed by exposure to 6% oxygen for 2 h) and treated with vehicle (control) or leptin. Spatial memory was analyzed in the present study using the Morris water maze test 19 days following ligation. Over the 24‑day post‑surgical observation period, capture‑resistance test, forelimb suspension and open field tests were conducted to evaluate motor function and anxiety‑associated behavior. Treatment with leptin did not affect survival rate or body weight. Treatment with leptin increased the number of platform crossings in rats with premature brain damage in the Morris water maze test, which was used to assess spatial memory. Multivariate analysis revealed that leptin reduced the latency to finding the platform location, independent of gender and weight. In the capture‑resistance, forelimb suspension and open field tests, there were no differences between animals administered leptin and the sham group. Collectively, the results of the present study suggested that leptin may alleviate spatial memory impairment resulting from premature brain damage, independent of gender or weight. These results may improve understanding of the neuroprotective effects exhibited by leptin in infants with preterm brain damage.

Rapid Infant Prefrontal Cortex Development and Sensitivity to Early Environmental Experience

Over the last fifteen years, the emerging field of developmental cognitive neuroscience has described the relatively late development of prefrontal cortex in children and the relation between gradual structural changes and children's protracted development of prefrontal-dependent skills. Widespread recognition by the broader scientific community of the extended development of prefrontal cortex has led to the overwhelming perception of prefrontal cortex as a "late developing" region of the brain. However, despite its supposedly protracted development, multiple lines of research have converged to suggest that prefrontal cortex development may be particularly susceptible to individual differences in children's early environments. Recent studies demonstrate that the impacts of early adverse environments on prefrontal cortex are present very early in development: within the first year of life. This review provides a comprehensive overview of new neuroimaging evidence demonstrating that prefrontal cortex should be characterized as a "rapidly developing" region of the brain, discusses the converging impacts of early adversity on prefrontal circuits, and presents potential mechanisms via which adverse environments shape both concurrent and long-term measures of prefrontal cortex development. Given that environmentally-induced disparities are present in prefrontal cortex development within the first year of life, translational work in intervention and/or prevention science should focus on intervening early in development to take advantages of this early period of rapid prefrontal development and heightened plasticity.

Nonword Repetition and Language Outcomes in Young Children Born Preterm

Purpose

The aims of this study were to examine phonological short-term memory in children born preterm (PT) and to explore relations between this neuropsychological process and later language skills.

Method

Children born PT (n = 74) and full term (FT; n = 60) participated in a nonword repetition (NWR) task at 36 months old. Standardized measures of language skills were administered at 36 and 54 months old. Group differences in NWR task completion and NWR scores were analyzed. Hierarchical multiple regression analyses examined the extent to which NWR ability predicted later performance on language measures.

Results

More children born PT than FT did not complete the NWR task. Among children who completed the task, the performance of children born PT and FT was not statistically different. NWR scores at 36 months old accounted for significant unique variance in language scores at 54 months old in both groups. Birth group did not moderate the relation between NWR and later language performance.

Conclusions

These findings suggest that phonological short-term memory is an important skill underlying language development in both children born PT and FT. These findings have relevance to clinical practice in assessing children born PT.

Effects of Intestinal Microbiota on Brain Development in Humanized Gnotobiotic Mice

Poor growth in the Neonatal Intensive Care Unit is associated with an increased risk for poor neurodevelopmental outcomes for preterm infants, however the mechanism is unclear. The microbiome has increasingly been recognized as a modifiable environmental factor to influence host development. Here we explore the hypothesis that the microbiome influences both growth phenotype and brain development. A germ free mouse transfaunation model was used to examine the effects of preterm infant microbiotas known to induce either high growth or low growth phenotypes on postnatal brain development. The microbiome which induced the low growth phenotype was associated with decreases in the neuronal markers NeuN and neurofilament-L as well as the myelination marker MBP when compared to the microbiome associated with the high growth phenotype. Additionally, poor growth phenotype-associated microbiota was associated with increased neuroinflammation marked by increased Nos1, as well as alteration in IGF-1 pathway including decreased circulating and brain IGF-1, decreased circulating IGFBP3, and increased Igfbp3 brain mRNA expression. This study suggests that growth-associated microbiota can influence early neuron and oligodendrocyte development and that this effect may be mediated by effects on neuroinflammation and circulating IGF-1.

IRE1α inhibition decreased TXNIP/NLRP3 inflammasome activation through miR-17-5p after neonatal hypoxic-ischemic brain injury in rats

Background

The endoplasmic reticulum (ER) is responsible for the control of correct protein folding and protein function which is crucial for cell survival. However, under pathological conditions, such as hypoxia–ischemia (HI), there is an accumulation of unfolded proteins thereby triggering the unfolded protein response (UPR) and causing ER stress which is associated with activation of several stress sensor signaling pathways, one of them being the inositol requiring enzyme-1 alpha (IRE1α) signaling pathway. The UPR is regarded as a potential contributor to neuronal cell death and inflammation after HI. In the present study, we sought to investigate whether microRNA-17 (miR-17), a potential IRE1α ribonuclease (RNase) substrate, arbitrates downregulation of thioredoxin-interacting protein (TXNIP) and consequent NLRP3 inflammasome activation in the immature brain after HI injury and whether inhibition of IRE1α may attenuate inflammation via miR-17/TXNIP regulation.

Methods

Postnatal day 10 rat pups (n = 287) were subjected to unilateral carotid artery ligation followed by 2.5 h of hypoxia (8% O₂). STF-083010, an IRE1α RNase inhibitor, was intranasally delivered at 1 h post-HI or followed by an additional one administration per day for 2 days. MiR-17-5p mimic or anti-miR-17-5p inhibitor was injected intracerebroventricularly at 48 h before HI. Infarct volume and body weight were used to evaluate the short-term effects while brain weight, gross and microscopic brain tissue morphologies, and neurobehavioral tests were conducted for the long-term evaluation. Western blots, immunofluorescence staining, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), and co-immunoprecipitation (Co-IP) were used for mechanism studies.

Results

Endogenous phosphorylated IRE1α expression was significantly increased after HI. Intranasal administration of STF-083010 alleviated brain injury and improved neurological behavior. MiR-17-5p expression was reduced after HI, and this decrease was attenuated by STF-083010 treatment. MiR-17-5p mimic administration ameliorated TXNIP expression, NLRP3 inflammasome activation, caspase-1 cleavage, and IL-1β production, as well as brain infarct volume. Conversely, anti-miR-17-5p inhibitor reversed IRE1α inhibition-induced decrease in TXNIP expression and inflammasome activation, as well as exacerbated brain injury after HI.

Conclusions

IRE1a-induced UPR pathway may contribute to inflammatory activation and brain injury following neonatal HI. IRE1a activation, through decay of miR-17-5p, elevated TXNIP expression to activate NLRP3 inflammasome and aggravated brain damage.

Electronic supplementary material

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Effect of T helper cell 1/T helper cell 2 balance and nuclear factor-κB on white matter injury in premature neonates

Incidence of white matter injury (WMI), which is featured as softening of white matter tissues, has recently increased. Previous studies have demonstrated a close correlation between T helper cell 1 and T helper cell 2 (Th1/Th2) imbalance and nuclear factor‑κB (NF‑κB) with brain disease. Their role in premature WMI, however, remains to be illustrated. Serum samples were collected from 60 premature WMI neonates, plus another control group of 60 premature babies without WMI. Patients were further divided into mild, moderate and severe WMI groups. Reverse transcription quantitative polymerase chain reaction was used to test mRNA expression levels of Th1/Th2 cytokines, including interleukin 2 (IL)‑2, tumor necrosis factor‑α (TNF‑α), IL‑4, IL‑10 and nuclear factor (NF)‑κB, whilst their serum levels were measured by ELISA. Their correlation with disease occurrence and progression were further analysed, to illustrate the effect of Th1/Th2 balance and NF‑κB on pathology of premature WMI. Serum levels of IL‑4 and IL‑10 were significantly decreased in premature WMI babies, whilst IL‑2, TNF‑α and NF‑κB were upregulated (P<0.05 vs. control group). With aggravated disease, IL‑4 and IL‑10 expression was further decreased while IL‑2, TNF‑α and NF‑κB were increased (P<0.05 vs. mild WMI group). Th1 cytokines IL‑2 and TNF‑α and NF‑κB were negatively correlated with Th2 cytokines IL‑4 and IL‑10. Disease severity was positively correlated with IL‑2, TNF‑α and NF‑κB expression, and was negatively correlated with IL‑4 and IL‑10 (P<0.05). Th1/Th2 imbalance and NF‑κB upregulation were observed in WMI pathogenesis, with elevated secretion of Th1 cytokines and decreased Th2 cytokines, suggesting that Th1/Th2 imbalance and NF‑κB upregulation may be a potential indicator for the early diagnosis and treatment of WMI pathogenesis and progression.

Preterm birth leads to hyper-reactive cognitive control processing and poor white matter organization in adulthood

Individuals born preterm with very low birth weight (VLBW; birth weight ≤ 1500 g) are at high risk for perinatal brain injuries and deviant brain development, leading to increased chances of later cognitive, emotional, and behavioral problems. Here we investigated the neuronal underpinnings of both reactive and proactive cognitive control processes in adults with VLBW. We included 32 adults born preterm with VLBW (before 37th week of gestation) and 32 term-born controls (birth weight ≥10th percentile for gestational age) between 22 and 24 years of age that have been followed prospectively since birth. Participants performed a well-validated Not-X continuous performance test (CPT) adapted for use in a mixed block- and event-related fMRI protocol. BOLD fMRI and DTI data was acquired on a 3T scanner. Performance on the Not-X CPT was highly similar between groups. However, the VLBW group demonstrated hyper-reactive cognitive control processing and disrupted white matter organization. The hyper-reactive brain activation signature in VLBW adults was associated with lower gestational age, lower fluid intelligence score, and anxiety problems. Automated Multi-Atlas Tract Extraction (AutoMATE) analyses revealed that this disruption of normal brain function was accompanied by poorer white matter organization in the anterior thalamic radiation and the cingulum, as reflected in both reduced fractional anisotropy and increased mean diffusivity. These findings show that the preterm behavioral phenotype is associated with predominantly reactive-, rather than proactive cognitive control processing, as well as white matter abnormalities, that may underlie common difficulties that many preterm born individuals experience in everyday life.