Early Life Experiences and Trajectories of Cognitive Development

Abstract

Background: Multiple factors constrain the trajectories of child cognitive development, but the drivers that differentiate the trajectories are unknown. We examine how multiple early life experiences differentiate patterns of cognitive development over the first 5 years of life in low-and middle-income settings.

Methods: Cognitive development of 835 children from the Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) multisite observational cohort study was assessed at 6, 15, 24 (Bayley Scales of Infant and Toddler Development), and 60 months (Wechsler Preschool and Primary Scale of Intelligence). Markers of socioeconomic status, infection, illness, dietary intake and status, anthropometry, and maternal factors were also assessed. Trajectories of development were determined by latent class-mixed models, and factors associated with class membership were examined by discriminant analysis.

Results: Five trajectory groups of cognitive development are described. The variables that best discriminated between trajectories included presence of stimulating and learning resources in the home, emotional or verbal responsivity of caregiver and the safety of the home environment (especially at 24 and 60 months), proportion of days (0-24 months) for which the child had diarrhea, acute lower respiratory infection, fever or vomiting, maternal reasoning ability, mean nutrient densities of zinc and phytate, and total energy from complementary foods (9-24 months).

Conclusions: A supporting and nurturing environment was the variable most strongly differentiating the most and least preferable trajectories of cognitive development. In addition, a higher quality diet promoted cognitive development while prolonged illness was indicative of less favorable patterns of development.

FIGURE 1

Profiles of the five latent classes; the bold line shows the mean of each trajectory group. Six classes were identified statistically, but two sparse and similar groups were combined into the late group. The number of children in each class is shown above each plot.

FIGURE 2

Left: the κ agreement between univariate linear discriminant analysis and the latent class model, only showing variables with κ ≥ 0.1. Middle: the multivariable sum of the CAT gives a rank score of the contribution of each variable to the overall discriminant analysis. Right: the cumulative (included from top to bottom) contribution of each variable to the κ agreement of the multivariable discriminant analysis model. ^a Factors derived from HOME Inventory.

FIGURE 3

Profiles for each trajectory group showing the CAT comparing each group to the pooled mean for the top 8 discriminating variables. Scores that are closer to the center indicate a negative association between a given variable and the probability of belonging to a class; scores that are further to the outer ring have a positive association with the probability of belonging to a class. The solid circle indicates a t score of zero, hence no association between the variable and a trajectory class.