Perinatal and childhood predictors of general cognitive outcome at 28 years in a very-low-birthweight national cohort

Modifiable factors associated with cognitive performance in Chinese adolescents: a national environment-wide association study

Growing evidence exists about the candidate factors of childhood cognitive performance, but mainly limited to single-exposure studies. We sought to systematically and simultaneously identify and validate a wide range of potential modifiable factors for childhood cognitive performance. We used data from five waves of data from the China Family Panel Studies (CFPS-2010, 2012, 2014, 2016 and 2018). Our analytical sample was restricted to those children aged 2-5 at baseline with valid exposure information. A total of 80 modifiable factors were identified. Childhood cognitive performance was assessed using vocabulary and mathematics test at wave 5. We used an environment-wide association study (EnWAS) to screen all exposure-outcome associations independently and used the least absolute shrinkage and selection operator (LASSO) variable selection algorithm to identify factors associated with cognitive performance. Multivariable linear model was then used to evaluate causal relationships between identified factors and cognitive performance. Of the 1305 participants included in the study (mean ± SD, 3.5 ± 1.1 years age at baseline, 45.1% girls). Eight factors were retained in the LASSO regression analysis. Six factors across community characteristics (percentage of poverty in the community; percentage of children in the community), household characteristics (family size), child health and behaviors (mobile internet access), parenting behaviors and cognitive enrichment (parental involvement in child' s education), and parental wellbeing (paternal happiness) domains were significantly associated with childhood cognition. Using a three-stage approach, this study validates several actionable targets for improving childhood cognitive performance.

Intellectual functioning in survivors of extremely low birthweight: Cognitive outcomes in childhood and adolescence

BACKGROUND

Infants born at extremely low birthweight (ELBW: ≤1000 g) are vulnerable to intellectual disabilities, but the factors that may distinguish between ELBW survivors with and without these impairments are not well understood. In this study, prospective associations between neonatal factors and functional outcomes in childhood and adolescence were compared in ELBW survivors with and without borderline intellectual functioning (BIF).

METHODS

Borderline intellectual functioning was defined by IQ < 85, assessed at 8 years. Among 146 ELBW survivors, 48 (33%) had IQ scores under 85, and 98 (67%) had scores equal to or over 85. Group differences in demographic and risk factors were assessed via t-test, chi-squared analysis or non-parametric tests. Neonatal factors that differed between ELBW groups were tested for association with adaptive behaviour assessed at age 5 years, and reading and arithmetic skills assessed at ages 8 and 15 years, using hierarchical regression models.

RESULTS

Extremely low birthweight survivors with BIF had significantly lower birthweights than ELBW survivors without BIF (790 vs. 855 g, P < 0.01) and were more likely to be born to mothers with lower socioeconomic status (SES) (78% vs. 48%, P < 0.01). These ELBW survivors also were more likely to be diagnosed with significant neurosensory impairment (NSI; 35% vs. 19%, P < 0.04), experienced more bronchopulmonary dysplasia (56% vs. 38%, P < 0.04), received more days of respiratory support (median 33 vs. 14 days, P < 0.01) and remained in hospital for longer periods (median 81 vs. 63 days, P < 0.03). Birthweight, familial SES, NSI and duration of respiratory support were significant predictors for one or more outcomes. Across groups, lower familial SES was associated with lower academic scores (Ps < 0.05), and NSI predicted lower adaptive functioning (Ps < 0.001). Other associations were moderated by group: among ELBW survivors with BIF, heavier birthweights predicted better arithmetic skills, the presence of NSI was associated with poorer arithmetic skills and more ventilation days predicted poorer reading skills.

CONCLUSIONS

At birth, ELBW survivors with BIF faced more physiological and social disadvantages and required more medical intervention than their ELBW peers without BIF. Smaller birth size, NSI burden and prolonged neonatal ventilatory support displayed gradients of risk for childhood and adolescent academic outcomes across groups. Whereas academic performance in ELBW survivors with BIF was sensitive to variation in birth size, NSI or ventilation days, ELBW survivors without BIF attained thresholds of intellectual ability that were sufficient to support higher levels of academic performance at both ages, regardless of their status on these factors. The findings are discussed in relation to Zigler's developmental theory of intellectual disability.

Comparative evaluation of the health utilities index mark 3 and the short form 6D: evidence from an individual participant data meta-analysis of very preterm and very low birthweight adults

BACKGROUND

The most appropriate preference-based health-related quality of life (HRQoL) instruments for trials or research studies that ascertain the consequences of individuals born very preterm and/or low birthweight (VP/VLBW) are not known. Agreement between the HUI3 and SF-6D multi-attribute utility measures have not been previously investigated for VP/VLBW and normal birthweight or term-born controls. This study examined the agreement between the outputs of the HUI3 and SF-6D measures among adults born VP/VLBW and normal birthweight or term born controls.

METHODS

We used two prospective cohorts of individuals born VP/VLBW and controls contributing to the 'Research on European Children and Adults Born Preterm' (RECAP) consortium which assessed HRQoL using two preference-based measures. The combined dataset of individual participant data (IPD) included 407 adult VP/VLBW survivors and 367 controls, ranging in age from 18 to 26 years. Bland-Altman plots, intra-class correlation coefficients, and generalized linear mixed models in a one-step approach were used to examine agreement between the measures.

RESULTS

There was significant discordance between the HUI3 and SF-6D multi-attribute utility measures in the VP/VLBW sample, controls, and in the combined samples. Agreement between the HUI3 and SF-6D multi-attribute utility measures was weaker in controls compared with VP/VLBW individuals.

CONCLUSIONS AND RELEVANCE

The HUI3 and SF-6D each provide unique information on different aspects of health status across the groups. The HUI3 better captures preterm-related changes to HRQoL in adulthood compared to SF-6D. Studies focused on measuring physical or cognitive aspects of health will likely benefit from using the HUI3 instead of the SF-6D, regardless of gestational age at birth and birthweight status.

Health-Related Quality-of-Life Outcomes of Very Preterm or Very Low Birth Weight Adults: Evidence From an Individual Participant Data Meta-Analysis

BACKGROUND AND OBJECTIVE

Assessment of health-related quality of life for individuals born very preterm and/or low birthweight (VP/VLBW) offers valuable complementary information alongside biomedical assessments. However, the impact of VP/VLBW status on health-related quality of life in adulthood is inconclusive. The objective of this study was to examine associations between VP/VLBW status and preference-based health-related quality-of-life outcomes in early adulthood.

METHODS

Individual participant data were obtained from five prospective cohorts of individuals born VP/VLBW and controls contributing to the 'Research on European Children and Adults Born Preterm' Consortium. The combined dataset included over 2100 adult VP/VLBW survivors with an age range of 18-29 years. The main exposure was defined as birth before 32 weeks' gestation (VP) and/or birth weight below 1500 g (VLBW). Outcome measures included multi-attribute utility scores generated by the Health Utilities Index Mark 3 and the Short Form 6D. Data were analysed using generalised linear mixed models in a one-step approach using fixed-effects and random-effects models.

RESULTS

VP/VLBW status was associated with a significant difference in the Health Utilities Index Mark 3 multi-attribute utility score of - 0.06 (95% confidence interval - 0.08, - 0.04) in comparison to birth at term or at normal birthweight; this was not replicated for the Short Form 6D. Impacted functional domains included vision, ambulation, dexterity and cognition. VP/VLBW status was not associated with poorer emotional or social functioning, or increased pain.

CONCLUSIONS

VP/VLBW status is associated with lower overall health-related quality of life in early adulthood, particularly in terms of physical and cognitive functioning. Further studies that estimate the effects of VP/VLBW status on health-related quality-of-life outcomes in mid and late adulthood are needed.

Vitamin D status in pregnancy and childhood associates with intelligence quotient at age 7 years: An Odense child cohort study

OBJECTIVES

Animal studies indicate a key role for vitamin D in brain development and function, but observational studies in humans only suggests a borderline positive association between prenatal vitamin D exposure and cognitive development in the offspring. Knowledge gaps include insights in exposure time window and differences by sex for the association. We aimed to investigate the association between blood concentrations of serum 25-hydroxyvitamin D measured at four different time points and intelligence quotient score at the age of 7 years, including analyses spilt by child sex.

METHODS

In Odense child cohort, we included 1404 mother-child pairs with serum 25-hydroxyvitamin D data from early pregnancy to age 7 years. Full-scale intelligence quotient was assessed with Wechsler Intelligence Scale for Children - fifth edition. Associations were adjusted for maternal education, pre-pregnancy body mass index, gestational age, sex and head circumference. Subanalyses stratified by sex were performed.

RESULTS

The median (interquartile range) serum 25-hydroxyvitamin D in cord was 45.88 (31.15-61.08) nmol/L; early pregnancy, 66.45 (51.29-78.74); late pregnancy, 79.13 (59.69-97.31); 7 years, 66.29 (53.45-80.23) nmol/L. The mean (standard deviation) full-scale intelligence quotient was 99.44 (11.98). In adjusted analyses, cord serum 25-hydroxyvitamin D < 50 nmol/L was associated with 2.2 points lower full-scale intelligence quotient compared to the reference (50-75 nmol/L) in boys, β = -2.2; 95% confidence interval = [-4.3, -0.1], p = 0.039. The same association with full-scale intelligence quotient was found for early pregnancy serum 25-hydroxyvitamin D, β = -2.5 [-4.6, -0.3], p = 0.025, primarily driven by an association in boys, β = -4.0 [-7.2, -0.8], p = 0.015; and for serum 25-hydroxyvitamin D at 7 years in girls, β = -3.0 [-6.0, -0.1], p = 0.042.

CONCLUSION

In this cohort, serum 25-hydroxyvitamin D < 50 nmol/L in both early gestation and cord blood in boys and current serum 25-hydroxyvitamin D < 50 nmol/L in girls were independent risk factors for two to four points lower full-scale intelligence quotient at the age of 7 years. Vulnerability to hypovitaminosis D, especially in pregnancy, may relate to child sex.

Neurodevelopmental outcomes of premature infants with intraventricular hemorrhage across a lifespan

Neurodevelopmental impairment rates remain high among extremely preterm and very low birth weight infants. This review describes the rates of brain injury and neuro-developmental impairment at 2,3 years, early school age, adolescence, and young adulthood for survivors with intraventricular hemorrhage (IVH). Former preterm infants with a history of high-grade IVH are at the greatest risk of adverse neurodevelopmental outcomes. There is variability, however, in definitions of brain injury, methods for assessing brain injury, and definitions of adverse outcomes among multicenter networks. Despite differences in methods described in publications, perinatal grade III-IV intraventricular hemorrhage, post-hemorrhagic hydrocephalus, and white matter injury are consistently associated with increased rates of adverse motor and cognitive outcomes in the first 2,3 years of life, at early school age, in adolescence and early adulthood. Effects of socioeconomic status on outcomes, however, increase with the increasing age of the child. In summary, although preterm survivors of IVH are at an increased risk of adverse outcomes across a lifetime, there is evidence that social and environmental factors contribute to recovery over time.

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.

Investigating brain structural maturation in children and adolescents born very preterm using the brain age framework

Very preterm (VP) birth is associated with an increased risk for later neurodevelopmental and behavioural challenges. Although the neurobiological underpinnings of such challenges continue to be explored, previous studies have reported brain volume and morphology alterations in children and adolescents born VP compared with full-term (FT)-born controls. How these alterations relate to the trajectory of brain maturation, with potential implications for later brain ageing, remains unclear. In this longitudinal study, we investigate the relationship between VP birth and brain development during childhood and adolescence. We construct a normative 'brain age' model to predict age over childhood and adolescence based on measures of brain cortical and subcortical volumes and cortical morphology from structural MRI of a dataset of typically developing children aged 3-21 years (n = 768). Using this model, we examined deviations from normative brain development in a separate dataset of children and adolescents born VP (<30 weeks' gestation) at two timepoints (ages 7 and 13 years) compared with FT-born controls (120 VP and 29 FT children at age 7 years; 140 VP and 47 FT children at age 13 years). Brain age delta (brain-predicted age minus chronological age) was, on average, higher in the VP group at both timepoints compared with controls, however this difference had a small to medium effect size and was not statistically significant. Variance in brain age delta was higher in the VP group compared with controls; this difference was significant at the 13-year timepoint. Within the VP group, there was little evidence of associations between brain age delta and perinatal risk factors or cognitive and motor outcomes. Under the brain age framework, our results may suggest that children and adolescents born VP have similar brain structural developmental trajectories to term-born peers between 7 and 13 years of age.

Association of Very Preterm Birth or Very Low Birth Weight With Intelligence in Adulthood: An Individual Participant Data Meta-analysis

IMPORTANCE

Birth before 32 weeks' gestation (very preterm [VPT]) and birth weight below 1500 g (very low birth weight [VLBW]) have been associated with lower cognitive performance in childhood. However, there are few investigations of the association of neonatal morbidities and maternal educational levels with the adult cognitive performance of individuals born VPT or VLBW (VPT/VLBW).

OBJECTIVE

To assess differences in adult IQ between VPT/VLBW and term-born individuals and to examine the association of adult IQ with cohort factors, neonatal morbidities, and maternal educational level among VPT/VLBW participants.

DATA SOURCES

Systematic review of published data from PubMed and meta-analysis of individual participant data (IPD) of cohorts from 2 consortia (Research on European Children and Adults Born Preterm [RECAP] and Adults Born Preterm International Collaboration [APIC]).

STUDY SELECTION

The meta-analysis included prospective longitudinal cohort studies that assessed the full-scale IQ of adults born VPT or VLBW and respective control groups comprising term-born adults.

DATA EXTRACTION AND SYNTHESIS

The study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline for analyses of individual participant data and identified 8 studies that provided data from 2135 adults (1068 VPT/VLBW and 1067 term-born participants) born between 1978 and 1995. Meta-analyses of IPD were performed using a 1-stage approach, treating VPT birth or VLBW and cohort as random effects.

MAIN OUTCOMES AND MEASURES

Full-scale IQ scores were converted to z scores within each cohort using the combined SD of VPT/VLBW participants and a control group of term-born participants, with scores centered on the mean of the control group.

RESULTS

A total of 426 records were identified and screened. After exclusions, 13 studies were included in the aggregate meta-analysis. The IPD meta-analysis included 8 of the 9 RECAP and APIC cohorts with adult IQ data. The mean (SD) age among the 8 IPD cohorts was 24.6 (4.3) years, and 1163 participants (54.5%) were women. In unadjusted analyses, VPT/VLBW participants had mean adult IQ scores that were 0.78 SD (95% CI, -0.90 to -0.66 SD) lower than term-born participants, equivalent to a difference of 12 IQ points. Among VPT/VLBW participants, lower gestational age (score difference per week of gestation, 0.11; 95% CI, 0.07-0.14), lower birth weight z scores (score difference per 1.0 SD, 0.21; 95% CI, 0.14-0.28), the presence of neonatal bronchopulmonary dysplasia (score difference, -0.16; 95% CI, -0.30 to -0.02) or any grade of intraventricular hemorrhage (score difference, -0.19; 95% CI, -0.33 to -0.05), and lower maternal educational level (score difference, 0.26; 95% CI, 0.17-0.35) were all significantly associated with lower IQ scores in adulthood.

CONCLUSIONS AND RELEVANCE

In this IPD meta-analysis, lower gestational age, lower weight for gestational age, neonatal morbidities, and lower maternal educational levels were all important risk factors associated with lower IQ among young adults born VPT or VLBW.