Linear Growth through 12 Years is Weakly but Consistently Associated with Language and Math Achievement Scores at Age 12 Years in 4 Low- or Middle-Income Countries

Current Understanding of Giardia lamblia and Pathogenesis of Stunting and Cognitive Deficits in Children from Low- and Middle-Income Countries

Purpose of Review

Giardia lamblia is a common intestinal parasite worldwide, mainly in children from low- and middle-income countries (LMIC). Also, it has been associated with increased intestinal permeability, stunting, and cognitive impairment. Nonetheless, the pathogenesis of long-term consequences is difficult to elucidate.

Recent Findings

Recent studies try to understand the long-term consequences of Giardia infections. First, well-characterized studies associate Giardia with intestinal damage and child growth. Second, infections appear not to be associated with inflammation, but "lack of inflammation" may not, however, entirely exclude a pro-inflammatory pathway. Finally, some important amino acids are lower and could contribute to prolongate stunting and cognitive deficit.

Summary

Giardia infections in LMIC used to be associated with child growth shortfalls, gut permeability, and cognitive deficits. Multifactorial effects could be associated with Giardia, including nutritional, altered microbiota, and generation of potentially toxic microbial metabolic byproducts, all together increasing risk of long-term outcomes.

Short stature and language development in the United Kingdom: a longitudinal analysis of children from the Millennium Cohort Study

BACKGROUND

In low- and middle-income countries, poverty and impaired growth prevent children from meeting their cognitive developmental potential. There are few studies investigating these relationships in high-income settings.

METHODS

Participants were 12,536 children born between 2000 and 2002 in the UK and participating in the Millennium Cohort Study (MCS). Short stature was defined as having a height-for-age 2 or more standard deviations below the median (≤ - 2 SDS) at age 3 years. Standardized British Abilities Scales II (BAS II) language measures, used to assess language development at ages 3, 5, 7 and 11 years, were the main outcome assessed.

RESULTS

Children with short stature at age 3 years (4.1%) had language development scores that were consistently lower from ages 3 to 11 years (- 0.26 standard deviations (SD) (95% CI - 0.37, - 0.15)). This effect was attenuated but remained significant after adjustment for covariates. Trajectory analysis produced four distinct patterns of language development scores (low-declining, low-improving, average and high). Multinomial logistic regression models showed that children with short stature had a higher risk of being in the low-declining group, relative to the average group (relative risk ratio (RRR) = 2.11 (95% CI 1.51, 2.95)). They were also less likely to be in the high-scoring group (RRR = 0.65 (0.52, 0.82)). Children with short stature at age 3 years who had 'caught up' by age 5 years (height-for-age ≥ 2 SDS) did not have significantly different scores from children with persistent short stature, but had a higher probability of being in the high-performing group than children without catch-up growth (RRR = 1.84 (1.11, 3.07)).

CONCLUSIONS

Short stature at age 3 years was associated with lower language development scores at ages 3 to 11 years in UK children. These associations remained significant after adjustment for socioeconomic, child and parental factors.

Early childhood undernutrition, preadolescent physical growth, and cognitive achievement in India: A population-based cohort study

BACKGROUND

There is a lack of nationally representative estimates for the consequences of early childhood undernutrition on preadolescent outcomes in India. Understanding this relationship is helpful to develop interventions that not only prevent child undernutrition but also mitigate its consequences.

METHODS AND FINDINGS

In this cohort study, we analyzed prospectively gathered data from 2 waves of the India Human Development Survey (IHDS) to investigate the association of undernutrition during early childhood (0 to 5 years) in 2004 to 2005 with physical and cognitive outcomes during preadolescent (8 to 11 years) years in 2011 to 2012. These surveys interviewed 41,554 households across all 33 states and union territories in India in 2004 to 2005 and reinterviewed 83% of the households in 2011 to 2012. Primary exposure was assessed using the Composite Index of Anthropometric Failure (CIAF) based on 2004 to 2005 survey. Primary outcomes were short stature (height-for-age z-score [HAZ] <-2), thinness (body mass index [BMI] <18.5 kg/m2), reading, and arithmetic skills during preadolescence based on the 2011 to 2012 survey. Survey-weighted generalized linear models were used, and effect modification based on child sex and sociodemographic variables were evaluated using 3-way interaction terms. Of the 7,868 children included in this analysis, 4,334 (57.3%) were undernourished. Being undernourished was associated with increased odds of short stature (odds ratio [OR] 1.73, 95% confidence interval [CI] 1.45 to 2.06) and thinness (OR 1.52, 95% CI 1.33 to 1.73) during the preadolescent period, while it was associated with decreased odds of achieving a higher reading (cumulative odds ratio [cumOR]: 0.76, 0.66 to 0.87) and arithmetic (cumOR: 0.72, 0.63 to 0.82) outcomes. The disparity in outcomes based on CIAF increased with age, especially for female children. Increased level of female education within the household reduced the disadvantages of undernutrition among female children. Study limitations include observational and missing data, which limit our ability to draw strong causal inferences.

CONCLUSIONS

In this study, we found that early child undernutrition was associated with several adverse preadolescent physical and cognitive outcomes, especially among female children. Improved female education mitigates this association. Female education promotion should assume a central role in Indian public health policy making.

Patterns of Growth in Childhood in Relation to Adult Schooling Attainment and Intelligence Quotient in 6 Birth Cohorts in Low- and Middle-Income Countries: Evidence from the Consortium of Health-Oriented Research in Transitioning Societies (COHORTS)

BACKGROUND

Growth faltering has been associated with poor intellectual performance. The relative strengths of associations between growth in early and in later childhood remain underexplored.

OBJECTIVES

We examined the association between growth in childhood and adult human capital in 5 low- and middle-income countries (LMICs).

METHODS

We analyzed data from 9503 participants in 6 prospective birth cohorts from 5 LMICs (Brazil, Guatemala, India, the Philippines, and South Africa). We used linear and quasi-Poisson regression models to assess the associations between measures of height and relative weight at 4 age intervals [birth, age ∼2 y, midchildhood (MC), adulthood] and 2 dimensions of adult human capital [schooling attainment and Intelligence Quotient (IQ)].

RESULTS

Meta-analysis of site- and sex-specific estimates showed statistically significant associations between size at birth and height at ∼2 y and the 2 outcomes (P < 0.001). Weight and length at birth and linear growth from birth to ∼2 y of age (1 z-score difference) were positively associated with schooling attainment (β: 0.13; 95% CI: 0.08, 0.19, β: 0.17; 95% CI: 0.07, 0.32, and β: 0.25, 95% CI: 0.10, 0.40, respectively) and adult IQ (β: 0.74, 95% CI: 0.35, 1.14, β: 0.73, 95% CI: 0.35, 1.10, and β: 1.52, 95% CI: 0.96, 2.08, respectively). Linear growth from age 2 y to MC and from MC to adulthood was not associated with higher school attainment or IQ. Change in relative weight in early childhood, MC, and adulthood was not associated with either outcome.

CONCLUSIONS

Linear growth in the first 1000 d is a predictor of schooling attainment and IQ in adulthood in LMICs. Linear growth in later periods was not associated with either of these outcomes. Changes in relative weight across the life course were not associated with schooling and IQ in adulthood.

Engaging Mothers on the Growth of School-Age Children in a Rural South African Health and Demographic Site: A Qualitative Insight

A qualitative study was conducted to explore mothers' insights on the growth of school-age children in a rural Health and Demographic site of Limpopo Province, in South Africa. The participants were selected using purposive sampling. Data were collected from seven focus group discussions, which were audio-taped and transcribed verbatim. NVivo10 was used to analyse interview transcripts, following qualitative thematic analysis. Fifty-four mothers aged between 27 and 52 years were interviewed. Unfavourable sociodemographic status with poor living conditions of mothers were observed, particularly in terms of unemployment, minimal tertiary education, and rural locality. The perceptions of mothers on child growth linked growth of their children to various factors such as poverty and socioeconomic status, genetic/family heredity, and household environment. Mothers further related child growth to purchasing power and decisions regarding types of food, food unavailability, affordability issues, feeding beliefs and practices; and child food preferences, school feeding schemes, and maternal and societal cultural beliefs and practices. Despite their concerns, mothers perceived that their children were growing well, but differently. It is worth noting that the views of mothers on child growth were up to their aptitude level and might have been restricted due to their level of education and rural locality. Hence, there is a need for novel information, education, and communication strategies to effectively reach mothers, especially in rural areas, regarding the importance of identifying children with growth failure and its prevention. Mothers should be able to identify when a child is affected by growth failure and to seek healthcare, in order to prevent children from progressing to severe forms. This study informs on the timing of nutritional interventions for children and context-specific health promotion and health education programs to improve the knowledge of mothers on child growth.

Linear Growth between Early and Late Childhood and Cognitive Outcomes at 6-9 Years of Age

OBJECTIVES

To assess the extent to which linear growth beyond the early years of life determines later cognitive development.

STUDY DESIGN

We revisited children from New Delhi, India, who had participated in a randomized controlled trial 6 years before and assessed neurodevelopment using standardized and validated psychometric tools (Wechsler Intelligence Scale for Children, 4th edition; Crichton Vocabulary Scales; and Neuropsychological test battery). The associations of change in height for age z scores between early (12-36 months) and late (6-9 years) childhood with cognitive outcomes at 6-9 years of age were explored using linear regression models, after adjustment for appropriate confounders.

RESULTS

Out of the 1000 North Indian children who were enrolled in the original study, 791 consented to participate in this follow-up. Height for age z scores in the first 2 years of life was significantly associated with both the Wechsler Intelligence Scale for Children-Crichton Vocabulary Scales (standardized β coefficient [β], 0.15; 95% CI, 0.08-0.23), and the Neuropsychological test battery-II z-score (β, 0.09; 95% CI, 0.03-0.18) at 6-9 years of age. There were no significant associations between change in height for age z scores between early and later childhood and Wechsler Intelligence Scale for Children-Crichton Vocabulary Scales (β, -0.03; 95% CI, -0.11 to 0.04) or Neuropsychological test battery-II z-scores (β, -0.04; 95% CI, -0.12 to 0.06).

CONCLUSIONS

Linear growth between early and late childhood is not associated with later cognitive outcomes. Our findings support the current practice of investing public health efforts to accelerate linear growth in the first 2-3 years of life.

Associations between growth from birth to 18 years, intelligence, and schooling in a Brazilian cohort

BACKGROUND

Growth faltering in the first 1000 d is associated with lower human capital among adults. The existence of a second window of opportunity for nutritional interventions during adolescence has been postulated.

OBJECTIVES

We aimed to verify the associations between growth from birth to 18 y and intelligence and schooling in a cohort.

METHODS

A total of 5249 hospital-born infants in Pelotas, Brazil, were enrolled during 1993. Follow-up visits to random subsamples took place at 6, 12, and 48 mo and to the full cohort at 11, 15, and 18 y. Weight and length/height were collected in all visits. The Wechsler Adult Intelligence Scale was applied at age 18 y, and primary school completion was recorded. Conditional length/height and conditional BMI were calculated and expressed as z scores according to the WHO Growth Standards. These express the difference between observed and expected size at a given age based on a regression that includes earlier anthropometric measures. Analyses were adjusted for income, parental education, maternal skin color and smoking, and breastfeeding duration.

RESULTS

In the adjusted analyses, participants with conditional length ≥1 z score at 1 y had mean intelligence quotient (IQ) scores at 18 y 4.50 points (95% CI: 1.08, 7.92) higher than those with conditional length ≤-1 at 1 y. For height-for-age at 4 y, this difference was equal to 3.70 (95% CI: 0.49, 6.90) IQ points. There were no associations between conditional height at 11, 15, or 18 y and IQ. For the same previously mentioned comparison, the prevalence ratio for less than primary schooling was 1.42 (95% CI: 1.12, 1.80) for conditional height at 1 y. There were no consistent associations with conditional BMI.

CONCLUSIONS

Our findings show that adolescent growth is not associated with intelligence and schooling, and are consistent with the literature on the associations between intelligence and schooling and early linear growth.

Socio-demographic factors associated with normal linear growth among pre-school children living in better-off households: A multi-country analysis of nationally representative data

This study examined the socio-demographic factors associated with normal linear growth among pre-school children living in better-off households, using survey data from Ghana, Kenya, Nigeria, Mozambique and Democratic Republic of Congo (DRC). The primary outcome variable was child height-for-age z-scores (HAZ), categorised into HAZ≥-2SD (normal growth/not stunted) and HAZ<-2 (stunted). Using logistic regression, we estimated adjusted odds ratios (aORs) of the factors associated with normal growth. Higher maternal weight (measured by body mass index) was associated with increased odds of normal growth in Mozambique, DRC, Kenya and Nigeria. A unit increase in maternal years of education was associated with increased odds in normal growth in DRC (aOR = 1.06, 95% CI = 1.03, 1.09), Ghana (aOR = 1.08, 95% CI = 1.04, 1.12), Mozambique (aOR = 1.08, 95% CI = 1.05, 1.11) and Nigeria (aOR = 1.07, 95% CI = 1.06, 1.08). A year increase in maternal age was positively associated with normal growth in all the five countries. Breastfeeding was associated with increased odds of normal growth in Nigeria (aOR = 1.30, 95% CI = 1.16, 1.46) and Kenya (aOR = 1.37, 95% CI = 1.05, 1.79). Children of working mothers had 25% (aOR = 0.75, 95% CI = 0.60, 0.93) reduced odds of normal growth in DRC. A unit change in maternal parity was associated with 10% (aOR = 0.90, 95% CI = 0.84, 0.97), 23% (aOR = 0.77, 95% CI = 0.63, 0.93), 25% (aOR = 0.75, 95% CI = 0.69, 0.82), 6% (aOR = 0.94, 95% CI = 0.89, 0.99) and 5% (aOR = 0.95, 95% CI = 0.92, 0.99) reduced odds of normal growth in DRC, Ghana, Kenya, Mozambique and Nigeria, respectively. A child being a male was associated with 18% (aOR = 0.82, 95% CI = 0.68, 0.98), 40% (aOR = 0.60, 95% CI = 0.40, 0.89), 37% (aOR = 0.63, 95% CI = 0.51, 0.77) and 21% (aOR = 0.79, 95% CI = 0.71, 0.87) reduced odds of normal child growth in DRC, Ghana, Kenya and Nigeria, respectively. In conclusion, maternal education, weight, age, breastfeeding and antenatal care are positively associated with normal child growth. In contrast, maternal parity, employment, and child sex and age are associated negatively with normal growth. Interventions to improve child growth should take into account these differential effects.

Impact of early-onset persistent stunting on cognitive development at 5 years of age: Results from a multi-country cohort study

Background

Globally more than 150 million children under age 5 years were stunted in 2018, primarily in low- and middle-income countries (LMICs), and the impact of early-onset, persistent stunting has not been well explored. To explore the association between early-onset persistent stunting in children and cognitive development at 5 years of age, and to identify the factors associated with early-onset stunting.

Methods and findings

Children from the MAL-ED cohort study were followed from birth to 5 years of age in six LMICs. The Wechsler Preschool Primary Scales of Intelligence (WPPSI) was used to assess cognitive abilities (fluid reasoning) at 5 years and was adapted for each culture. Stunting was categorized as early-onset persistent (first stunted at 1–6 months and persisting at 60 months), early-onset recovered (first stunted at 1–6 months and not stunted at 60 months), late-onset persistent (first stunted at 7–24 months and persisting at 60 months), late-onset recovered (first stunted at 7–24 months and not stunted at 60 months), and never (never stunted). Mixed effects linear models were used to estimate the relationship between stunting status and cognitive development. Children with early-onset persistent stunting had significantly lower cognitive scores (-2.10 (95% CI: -3.85, -0.35)) compared with those who were never stunted. Transferrin receptor (TfR) was also negatively associated with cognitive development (-0.31 (95% CI: -0.49, -0.13)), while the HOME inventory, an index of quality of the home environment (0.46 (95% CI: 0.21, 0.72)) and socio-economic status (1.50 (95% CI: 1.03, 1.98)) were positively associated with cognitive development.

Conclusions

Early-onset persistent stunting was associated with lower cognitive development in children at 5 years of age in this cohort of children.

Nutritional Status from 1 to 15 Years and Adolescent Learning for Boys and Girls in Ethiopia, India, Peru, and Vietnam

There has been little examination of: (1) associations of early-life nutrition and adolescent cognitive skills, (2) if they vary by gender, (3) if they differ by diverse contexts, and (4) contributions of post-infancy growth to adolescent cognitive attainment. We use Young Lives data on 7687 children from Ethiopia, India, Peru, and Vietnam to undertake ordinary least squares estimates of associations between age-1 height-for-age z-score (HAZ) and age-15 cognitive outcomes (math, reading, vocabulary), controlling for child and household factors. Age-1 HAZ is positively associated with cognitive scores in all countries. Child gender-specific estimates for these coefficients either do not differ (math, reading) or favor girls (vocabulary). Augmenting models to include growth in HAZ between ages 1 and 15 years that was not predicted by HAZ at age 1 reveals that such improvements are associated with higher cognitive scores, but that sex-specific coefficients for this predictor favor boys in India and Peru. The results suggest that nutritional indicators at age 1 have gender-neutral associations with math and reading and favor girls for vocabulary achievement at age 15, but unpredicted improvements in HAZ by adolescence are associated with higher cognitive scores for boys than for girls. This evidence enriches our understanding of relationships between children’s nutritional trajectories during childhood and adolescent cognitive development, and how these associations vary by gender in some contexts to the possible disadvantage of girls.

The double burden of malnutrition among youth: Trajectories and inequalities in four emerging economies

As part of the nutritional transition, undernutrition is globally declining while changes brought by economic development have ushered in increases in overweight and its related economic costs and health consequences around the world. We examine trajectories in stunting and overweight from age one year to mid-adolescence and from mid-childhood to early adulthood among two cohorts from Ethiopia, India, Peru and Vietnam using data from the Young Lives study. We examine descriptive data and then model trajectories in stunting and overweight status over age. Group-based trajectory analysis with five ages of overweight and stunting for each country-cohort reveals (1) trajectories of catch-up growth for a subset of study children between the ages of 12 and 19 in the older cohort in Ethiopia (20.1% of the cohort), India (20.5%), Peru (16.9%), and Vietnam (14.0%); (2) trajectories of increasing probabilities of stunting as children age from 12 to 22 in the older cohort in India (22.2%) and Peru (30.7%); (3) trajectories of early (childhood) increases in overweight probabilities (younger cohort: India, 3.4%, Peru, 19.4%, and Vietnam, 8.1%), and of later (adolescence) increases in overweight probabilities (older cohort: Ethiopia, 0.5%, India, 6.3%, Peru, 40.9%, and Vietnam, 9.4%). Multinomial logit prediction of membership in trajectory categories reveals that higher wealth quartiles and maternal schooling are protective against high stunting probability trajectory group membership, but higher wealth and urban residence predict high overweight probability trajectory group membership. This evidence suggests a window of opportunity for interventions to reduce stunting and to avert overweight development in adolescence, in addition to the often-emphasized first 1000 days after conception. A life-course approach to policies and programs to target both undernutrition and overweight should be considered.

The association of early linear growth and haemoglobin concentration with later cognitive, motor, and social-emotional development at preschool age in Ghana

It is important to identify the periods during childhood when exposure to environmental risk factors results in long-term neurodevelopmental deficits. Stunting and anaemia may be sensitive indicators of exposure to such risks. In a prospective cohort enrolled before birth, we investigated the association of developmental scores at 4-6 years with (a) birth length and linear growth during three postnatal periods and (2) haemoglobin (Hb) concentration at three time points. Children were participants in a follow-up study of a randomized controlled trial of nutritional supplementation in Ghana. At 4-6 years, cognitive, motor, and social-emotional developments were assessed using standard tests adapted for this population. We estimated the associations of length-for-age z-score (LAZ) at birth and postnatal linear growth (n = 710) and Hb (n = 617) with developmental scores in regression models, using multistage least squares analysis to calculate uncorrelated residuals for postnatal growth. Cognitive development at 4-6 years was significantly associated with LAZ at birth (β = 0.12, 95% CI = 0.05, 0.19), ΔLAZ from 6 to 18 months (β = 0.16, 95% CI = 0.04, 0.28), and Hb at 18 months (β = 0.13, 95% CI = 0.06, 0.20), but not with ΔLAZ during 0-6 months, ΔLAZ from 18 months to 4-6 years, Hb at 6 months, or Hb at 4-6 years. No evidence of associations with motor or social-emotional development were found. These results suggest that in similar contexts, the earlier periods prior to birth and up to 18 months are more sensitive to risk factors for long-term cognitive development associated with LAZ and Hb compared with later childhood. This may inform the optimal timing of interventions targeting improved cognitive development.

Meeting the World Health Organization Maternal Antenatal Care Guidelines Is Associated with Improved Early and Middle Childhood Cognition in Ethiopia

OBJECTIVE

To assess the association between meeting the World Health Organization (WHO) maternal antenatal care attendance guidelines and early and middle childhood cognition among impoverished Ethiopian children.

STUDY DESIGN

A total of 1914 impoverished Ethiopian children from the Young Lives longitudinal cohort study were included. Childhood cognition was assessed via the Cognitive Development Assessment (CDA) and Peabody Picture Vocabulary Test (PPVT) at ages 4-5 years; PPVT, Early Grade Reading Assessment (EGRA), and Math Test at ages 7-8 years; and PPVT, Math Test, and Reading Test at ages 11-12 years. Linear regression models were used to examine the association between maternal antenatal care attendance and childhood academic achievement test scores.

RESULTS

In the univariable analysis, children of mothers who received the WHO recommended 4+ antenatal care visits or received the WHO recommended first antenatal care visit during the first trimester scored higher on all academic achievement tests. In the multivariable analysis, children of mothers who received 4+ antenatal care visits scored significantly higher on the CDA at ages 4-5 years and Math Test at ages 7-8 years. Children of mothers who received antenatal care in the first trimester scored higher on the CDA at ages 4-5 years and Math Test scores at ages 11-12 years. Children of mothers who received both antenatal care in the first trimester and 4+ antenatal care visits scored significantly higher on the CDA at ages 4-5 years and Math Test at both ages 7-8 and 11-12 years.

CONCLUSIONS

Children of mothers who received the WHO recommended number and timing of antenatal care visits had significantly higher academic achievement scores across multiple domains during early and middle childhood. Promotion of antenatal care visit attendance may improve cognition through middle childhood.