Association between intelligence quotient scores and extremely low birth weight in school-age children

Neurodevelopmental assessments used to measure preschoolers' cognitive development in Latin America: a systematic review

OBJECTIVE

The objective of this study was to systematically review the standardized neurodevelopmental assessments used to study preschool-aged children's cognitive development in Spanish-speaking Latin America.

METHODS

The authors systematically searched PubMed, PsycINFO, and ERIC databases for peer-reviewed articles from Spanish-speaking Latin American countries. Articles were included if they measured cognitive development among children aged 2-6 years using at least one standardized assessment tool; 97 articles were included and reviewed in accordance with PRISMA guidelines to assess their use of these tools.

RESULTS

Ninety-seven studies across 13 countries used a total of 41 assessments to measure cognitive development; most widely used were the Wechsler intelligence scales (n = 46/97), particularly the Wechsler Preschool and Primary Scale of Intelligence and Wechsler Intelligence Scale for Children (n = 23 and 29, respectively). Other common assessments included the McCarthy Scales of Children's Abilities (n = 9), Raven's Progressive Matrices (n = 9), Child Neuropsychological Assessment (n = 8), and Peabody Picture Vocabulary Test (n = 7). In regions where normative data for a given assessment were unpublished, authors commonly used norms from the United States, Mexico, or Spain or did not report standard scores in their analyses.

CONCLUSIONS

The wide range of tools used in these studies presents a challenge for generalizing results when measuring the neurodevelopment of Latin American preschool-aged children. The low availability of normative data for specific regions reveals concerns if some tools are culturally and linguistically appropriate even when Spanish is a common language, particularly in low-resource settings. Future work to forge greater consistency in the use of validated measures, clarity in reporting research methods, and publication of regional normative data would benefit the field.

Psycho-communicative interruptions in hearing-impaired Egyptian Arabic-speaking children

Background

Hearing is critical for normal development and acquisition of language and speech, and hearing impairment exists when there is diminished sensitivity to the sounds normally heard. Several studies have suggested that one out of every two to three school-aged children with any degree of hearing impairment have academic, social, and behavioral difficulties. Purpose: to compare the degree of hearing loss regarding the psychological profile: behavioral, social, emotional, and cognition of hearing-impaired children, and then correlate this profile to language scale.

Results

Hearing-impaired children showed more language, emotion, and behavioral difficulties and spent less time communicating than children with normal hearing. The lowest academic, social, and behavioral scores were in severe hearing-impaired group than in the other two groups.

Conclusion

Even slight/mild hearing impairment can result in negative consequences in the psychological profile, behavioral, social, and emotional, and there is significant relationship between delayed language, anxiety, and child behavior problems. Without appropriate interventions, these children are at risk of developing mental health disorders.

Associations of birth size, infancy, and childhood growth with intelligence quotient at 5 years of age: a Danish cohort study

BACKGROUND

The correlates of prenatal and postnatal growth on Intelligence Quotient (IQ) in childhood in term-born children living in high-income countries are not well known.

OBJECTIVES

We examined how birth size and growth in infancy and childhood were associated with IQ at age 5 y in term-born children using path analysis.

METHODS

The study sample comprised 1719 children from the Danish National Birth Cohort who participated in a substudy in which psychologists assessed IQ using the Wechsler Primary and Preschool Scales of Intelligence-Revised. Measured weight, length/height, and head circumference at birth, 5 mo, 12 mo, and 5 y were included in a path model to estimate their total, indirect, and direct effects on IQ. All growth measures were included in the model as sex- and age-standardized z-scores.

RESULTS

After adjusting for potential confounders, a positive association between birth weight and IQ was observed, and 88% of the association was direct. Weight gain in infancy was associated with IQ [per z-score increase from 5 to 12 mo, IQ increased by 1.53 (95% CI: 0.14; 2.92) points] whereas weight gain from 12 mo to 5 y was not associated with IQ. Height and head circumference growth in childhood was associated with IQ [per z-score increase from 12 mo to 5 y, IQ increased by 0.98 (95% CI: 0.17; 1.79) and 2.09 (95% CI: 0.78; 3.41) points, respectively].

CONCLUSIONS

In children born at term in an affluent country with free access to health care, higher IQ was seen with greater size at birth and greater weight gain in infancy. Also, greater growth in height and head circumference throughout the first 5 y of life was associated with higher childhood IQ whereas greater weight gain after the first year of life was not.

A gradient relationship between low birth weight and IQ: A meta-analysis

Multiple studies have reported that individuals with low birth weights (LBW, <2500 g) have a lower intelligence quotient (IQ) than those with normal birth weights (NBW, ≥2500 g). Based on 57 eligible individual studies including 12,137 participants, we performed a meta-analysis to estimate the association between low birth weight and individuals' IQ scores (IQs). The pooled weight mean difference (WMD) in IQs between NBW and LBW individuals was 10 (95% CI 9.26-11.68). The WMD was stable regardless of age. No publication bias was detected. The mean IQs of the extremely low birth weight (ELBW, <1000 g), very low birth weight (VLBW, 1000-1499 g), moderately low birth weight (MLBW, 1500-2499 g) and NBW individuals were 91, 94, 99 and 104, respectively. Additionally, the WMD in IQs with NBW were 14, 10 and 7 for ELBW, VLBW, and MLBW individuals, respectively. Two studies permitted estimates of the influence of social determinants of health to the discrepancy in IQs, which was 13%. Since IQ is inherited and influenced by environmental factors, parental IQs and other factors contribute to residual confounding of the results. As the conclusion was based on population studies, it may not be applicable to a single individual.

Evaluation of developmental prognosis for esophageal atresia with tracheoesophageal fistula

PURPOSE

This study investigated risk factors for developmental disorders after the repair of esophageal atresia with tracheoesophageal fistula (EA/TEF).

METHODS

The clinical charts of all infants with EA/TEF (gross type C) treated at our institution between 1993 and 2013 were analyzed. Patients with chromosomal aberrations were excluded. Forty-seven patients were divided into groups according to the presence (D) or absence (N) of developmental disorders. Patients were assessed with appropriate developmental examinations at age >3 years.

RESULTS

Group D comprised 13 patients. The 34 patients in the group N had received a standard education. In groups D and N, gestational age was 36.5 versus 38.5 weeks, birth weight was 1808 versus 2662 g, and congenital cardiac anomalies occurred in 76.9 versus 23.5%. These differences reached significance. Operative data did not differ significantly. Overall complications occurred in 69.2 versus 29.4%, gastroesophageal reflux (GER) requiring fundoplication in 46.1 versus 8.8%, and oral ingestion difficulty in 61.5 versus 14.7%, which were significantly different. The frequencies of anastomotic leakage, anastomotic stricture, and recurrent fistula did not differ significantly.

CONCLUSION

Gestation, birth weight, and cardiac anomalies could be risk factors for developmental disorders. Moreover, overall complications, GER, and oral ingestion may affect development.

Early growth patterns are associated with intelligence quotient scores in children born small-for-gestational age

OBJECTIVE

To assess whether patterns of growth trajectory during infancy are associated with intelligence quotient (IQ) scores at 4 years of age in children born small-for-gestational age (SGA).

METHODS

Children in the Collaborative Perinatal Project born SGA were eligible for analysis. The primary outcome was the Stanford-Binet IQ score at 4 years of age. Growth patterns were defined based on changes in weight-for-age z-scores from birth to 4 months and 4 to 12 months of age and consisted of steady, early catch-up, late catch-up, constant catch-up, early catch-down, late catch-down, constant catch-down, early catch-up & late catch-down, and early catch-down & late catch-up. Multivariate linear regression was used to assess associations between patterns of growth and IQ.

RESULTS

We evaluated patterns of growth and IQ in 5640 children. Compared with children with steady growth, IQ scores were 2.9 [standard deviation (SD)=0.54], 1.5 (SD=0.63), and 2.2 (SD=0.9) higher in children with early catch-up, early catch-up and later catch-down, and constant catch-up growth patterns, respectively, and 4.4 (SD=1.4) and 3.9 (SD=1.5) lower in children with early catch-down & late catch-up, and early catch-down growth patterns, respectively.

CONCLUSIONS

Patterns in weight gain before 4 months of age were associated with differences in IQ scores at 4 years of age, with children with early catch-up having slightly higher IQ scores than children with steady growth and children with early catch-down having slightly lower IQ scores. These findings have implications for early infant nutrition in children born SGA.

Preventing academic difficulties in preterm children: a randomised controlled trial of an adaptive working memory training intervention - IMPRINT study

Background

Very preterm children exhibit difficulties in working memory, a key cognitive ability vital to learning information and the development of academic skills. Previous research suggests that an adaptive working memory training intervention (Cogmed) may improve working memory and other cognitive and behavioural domains, although further randomised controlled trials employing long-term outcomes are needed, and with populations at risk for working memory deficits, such as children born preterm.

In a cohort of extremely preterm (<28 weeks’ gestation)/extremely low birthweight (<1000 g) 7-year-olds, we will assess the effectiveness of Cogmed in improving academic functioning 2 years’ post-intervention. Secondary objectives are to assess the effectiveness of Cogmed in improving working memory and attention 2 weeks’, 12 months’ and 24 months’ post-intervention, and to investigate training related neuroplasticity in working memory neural networks 2 weeks’ post-intervention.

Methods/Design

This double-blind, placebo-controlled, randomised controlled trial aims to recruit 126 extremely preterm/extremely low birthweight 7-year-old children. Children attending mainstream school without major intellectual, sensory or physical impairments will be eligible. Participating children will undergo an extensive baseline cognitive assessment before being randomised to either an adaptive or placebo (non-adaptive) version of Cogmed. Cogmed is a computerised working memory training program consisting of 25 sessions completed over a 5 to 7 week period. Each training session takes approximately 35 minutes and will be completed in the child’s home. Structural, diffusion and functional Magnetic Resonance Imaging, which is optional for participants, will be completed prior to and 2 weeks following the training period. Follow-up assessments focusing on academic skills (primary outcome), working memory and attention (secondary outcomes) will be conducted at 2 weeks’, 12 months’ and 24 months’ post-intervention.

Discussion

To our knowledge, this study will be the first randomised controlled trial to (a) assess the effectiveness of Cogmed in school-aged extremely preterm/extremely low birthweight children, while incorporating advanced imaging techniques to investigate neural changes associated with adaptive working memory training, and (b) employ long-term follow-up to assess the potential benefit of improved working memory on academic functioning. If effective, Cogmed would serve as a valuable, available intervention for improving developmental outcomes for this population.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12612000124831.

Low birth weight and intelligence in adolescence and early adulthood: a meta-analysis

BACKGROUND

Research has demonstrated an association between low birth weight (LBW; <2500 g) and adverse intelligence quotient (IQ) outcomes in childhood and early adolescence. We systematically evaluated whether this association persists into late adolescence and early adulthood and also assessed the influence of age of IQ assessment on effect size.

METHODS

During Stage 1 (meta-analysis of data on adolescents/adults), we searched for relevant articles in PsychINFO, PubMed, Ovid, CINAHL, ProQuest and ERIC until February 2011 (no lower limit). Studies which assessed full-scale IQ among LBW individuals (<2500 g), aged 13 years and older, with a normal birth weight (NBW; ≥2500 g) comparison group were eligible. A random-effects meta-analysis provided a pooled estimate of the difference in IQ scores between LBW and NBW individuals. Publication bias was assessed using Rosenthal's classic fail-safe N and Duval and Tweedie's Trim and Fill. During Stage 2, we added data from the Kerr-Wilson et al. meta-analysis (which included data from children; in Meta-analysis of the association between preterm delivery and intelligence. Journal Public Health 2011;33:1-8) to our sample from Stage 1 and conducted a meta-regression to evaluate the effect of age of IQ assessment.

RESULTS

Using a total of 15 studies in Stage 1, it was demonstrated that NBW individuals scored an average of 7.63 IQ points higher than LBW individuals, CI = 5.95-9.31. After adjusting for publication bias, NBW samples demonstrated an IQ of 4.98 points higher than LBW samples, CI = 3.20-6.77. Furthermore, age at IQ assessment was a significant moderator of the association between birth weight and IQ, in that the effect size decreased from childhood into young adulthood.

CONCLUSIONS

Cognitive impairments associated with LBW persist into adolescence and early adulthood; however, the influence of LBW on IQ decreases from childhood to young adulthood. These conclusions must be interpreted with caution due to unmeasured variables and possible influence from publication bias.

Hearing loss, auditory neuropathy, and neurological co-morbidity in children with birthweight <750 g

BACKGROUND AND AIMS

The current literature considers a birthweight <1,500 g as a risk factor for sensorineural hearing loss (SNHL, hearing threshold >25 decibels), auditory neuropathy (AN), and several neurological sequelae. The aim of the study was to determine the frequency and risk factors associated with SNHL, AN, and neurological morbidity in a group of children with birthweights of <750 g treated at a neonatal care unit and recruited into a long-term follow-up program.

METHODS

A case-control study was carried out. Inclusion criteria were birthweight <750 g and born between the years 2000 and 2010. We performed brainstem auditory-evoked potentials (BAEP), evoked otoacoustic emissions (EOAE) and free-field audiometry (FFA) in this population. Neonatal variables and procedures were compared between children with SNHL and children with normal bilateral hearing (NBH).

RESULTS

A total of 93 children with a mean age of 4 years were included in the follow-up. Six children (6.4%) had SNHL and 87 had NBH. We were unable to identify AN in the sample. Mean weight for this sample was 673 ± 68 g and gestational age 27.5 ± 2 weeks. Variables reflecting differences between groups included days under mechanical ventilation, furosemide treatment, and bronchopulmonary dysplasia. In the SNHL group, three patients had periventricular leukomalacia, two had hydrocephalus, and one patient had cerebral palsy.

CONCLUSIONS

Frequency of SNHL in children with birthweights <750 g was higher than in other premature infants and was related with mechanical ventilation, furosemide application, and bronchopulmonary dysplasia. Association with other neurological morbidities was frequent. Early diagnosis and intervention are required.

Clinical benefits, costs, and cost-effectiveness of neonatal intensive care in Mexico

BACKGROUND

Neonatal intensive care improves survival, but is associated with high costs and disability amongst survivors. Recent health reform in Mexico launched a new subsidized insurance program, necessitating informed choices on the different interventions that might be covered by the program, including neonatal intensive care. The purpose of this study was to estimate the clinical outcomes, costs, and cost-effectiveness of neonatal intensive care in Mexico.

METHODS AND FINDINGS

A cost-effectiveness analysis was conducted using a decision analytic model of health and economic outcomes following preterm birth. Model parameters governing health outcomes were estimated from Mexican vital registration and hospital discharge databases, supplemented with meta-analyses and systematic reviews from the published literature. Costs were estimated on the basis of data provided by the Ministry of Health in Mexico and World Health Organization price lists, supplemented with published studies from other countries as needed. The model estimated changes in clinical outcomes, life expectancy, disability-free life expectancy, lifetime costs, disability-adjusted life years (DALYs), and incremental cost-effectiveness ratios (ICERs) for neonatal intensive care compared to no intensive care. Uncertainty around the results was characterized using one-way sensitivity analyses and a multivariate probabilistic sensitivity analysis. In the base-case analysis, neonatal intensive care for infants born at 24-26, 27-29, and 30-33 weeks gestational age prolonged life expectancy by 28, 43, and 34 years and averted 9, 15, and 12 DALYs, at incremental costs per infant of US$11,400, US$9,500, and US$3,000, respectively, compared to an alternative of no intensive care. The ICERs of neonatal intensive care at 24-26, 27-29, and 30-33 weeks were US$1,200, US$650, and US$240, per DALY averted, respectively. The findings were robust to variation in parameter values over wide ranges in sensitivity analyses.

CONCLUSIONS

Incremental cost-effectiveness ratios for neonatal intensive care imply very high value for money on the basis of conventional benchmarks for cost-effectiveness analysis. Please see later in the article for the Editors' Summary.

Association of brain weight value with morphometric and histochemical properties of cortical neurons and higher nervous activity parameters in rats in prepubertal period

We compared thickness of the neocortex, morphometric and histochemical characteristics of neurons in frontoparietal and parietal lobes and hippocampal field I in animals from great litters with lower brain weight (group 1) and from small (artificially reduced) litters with higher brain weight (group 2). It was found that the thickness of the neocortex in the frontoparietal and parietal lobes does not differ in the compared groups, while the size of neuronal cytoplasm in layer II of the frontoparietal and parietal lobes and in layer V of the frontoparietal lobe in group 2 animals was lower than in group 1. Nuclei of cortical neurons in layer II of the parietal and frontoparietal lobes and in frontoparietal lobe layer V in group 2 animals were smaller than in group 1. Neuronal nucleoli in group 2 animals were also smaller than in group 1 rats. RNA concentration in neuronal cytoplasm in the hippocampus and neocortex of group 2 rats was higher than in group 1 animals. NADPH-dehydrogenase activity in neurons of parietal lobe (layer II) and hippocampus in group 2 rats was lower than in group 1 animals, NADH-dehydrogenase activity was lower in parietal lobe layer II neurons. Group 2 rats demonstrated increased number of hanging down, sniffing, movements, entries into open and closed arms, and lower immobility time in the elevated plus-maze test.

Birth weight effects on children's mental, motor, and physical development: evidence from twins data

OBJECTIVE

To determine the effect of very low birth weight (VLBW; <1500 g) and moderately low birth weight (MLBW; 1500-2499 g) on children's mental and motor development and physical growth during the first 2 years of life and whether VLBW and MLBW babies catch up to normal birth weight (NBW; > or =2500 g) children by age 2.

METHODS

We use data on dizygotic (DZ) and monozygotic (MZ) twins and singleton births from the first two waves of the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B), a nationally representative dataset of children born in the US in 2001. We estimate the effects of VLBW and MLBW on children's mental and motor development scores, weight-for-age, weight-for-length, weight-for-height, and length-for-age z-scores at 9 months and 2 years. We examine whether differences in outcomes within twin pairs are related to differences in their birth weights. The within-twins analysis is conducted on samples of DZ and MZ twins. For comparison, we also estimate birth weight effects on child outcomes from multivariate linear regression models using the full singleton and twins' sample. We also estimate the effect of being small-for-gestational age (SGA; birth weight <10th percentile for gestation) using the same set of models in order to separate out the effects of fetal growth restriction from prematurity.

RESULTS

Evaluation of all births showed that VLBW and MLBW have large negative effects on mental development, motor development, and growth at 9 months and 2 years of age. However, results from within-twin models with DZ twins that control for shared maternal and environmental factors showed much less effect of birth weight on mental or motor development, but continued large effects on growth for the VLBW group. Within-twin models with MZ twins that control for shared maternal, environmental, and genetic factors showed statistically insignificant effects of birth weight on mental and motor development, but continued effects on growth. Similar patterns were found when examining the effects of SGA.

CONCLUSIONS

After controlling for the influence of maternal, environmental, and genetic factors, low birth weight has at most a small negative effect on children's mental and motor development in their first 2 years of life. However, low birth weight is a major risk factor for children's physical growth in the early years and there is no evidence of catch-up by age 2.

Associations between sleep duration patterns and behavioral/cognitive functioning at school entry

OBJECTIVE

The aim of the study was to investigate the associations between longitudinal sleep duration patterns and behavioral/cognitive functioning at school entry.

DESIGN, SETTING, AND PARTICIPANTS

Hyperactivity-impulsivity (HI), inattention, and daytime sleepiness scores were measured by questionnaire at 6 years of age in a sample of births from 1997 to 1998 in a Canadian province (N=1492). The Peabody Picture Vocabulary Test--Revised (PPVT-R) was administered at 5 years of age and the Block Design subtest (WISC-III) was administered at 6 years of age. Sleep duration was reported yearly by the children's mothers from age 2.5 to 6 years. A group-based semi-parametric mixture model was used to estimate developmental patterns of sleep duration. The relationships between sleep duration patterns and both behavioral items and neurodevelopmental tasks were tested using weighted multivariate logistic regression models to control for potentially confounding psychosocial factors.

RESULTS

Four sleep duration patterns were identified: short persistent (6.0%), short increasing (4.8%),10-hour persistent (50.3%), and 11-hour persistent (38.9%). The association of short sleep duration patterns with high HI scores (P=0.001), low PPVT-R performance (P=0.002), and low Block Design subtest performance (P=0.004) remained significant after adjusting for potentially confounding variables.

CONCLUSIONS

Shortened sleep duration, especially before the age of 41 months, is associated with externalizing problems such as HI and lower cognitive performance on neurodevelopmental tests. Results highlight the importance of giving a child the opportunity to sleep at least 10 hours per night throughout early childhood.

Body mass index and neuropsychological function in healthy children and adolescents

Elevated body mass index (BMI) is associated with adverse neurocognitive outcome in adults, including reduced neuropsychological test performance. It is unknown whether this relationship also exists in children and adolescents. A total of 478 children and adolescents (age 6-19) without significant medical or psychiatric history provided demographic information and completed a computerized cognitive test battery. Participants were categorized using clinical criteria into underweight, normal weight, at risk for overweight and overweight groups based on age and gender. Partial correlation and MANCOVA analyses adjusting for age and intellectual function found no relationship between BMI and cognitive test performance in the full sample. However, analyses performed separately by gender showed that underweight females exhibited poorer memory performance than other female BMI groups. These findings suggest that elevated BMI is not associated with cognitive function in healthy children and adolescents, though underweight might be a risk factor for reduced memory performance in females. Further work is needed to clarify the inconsistent findings between adults and minors.