Early Childhood Diarrhea Predicts Cognitive Delays in Later Childhood Independently of Malnutrition.

Understanding the complex relationship between early childhood infectious diseases, nutritional status, poverty, and cognitive development is significantly hindered by the lack of studies that adequately address confounding between these variables. This study assesses the independent contributions of early childhood diarrhea (ECD) and malnutrition on cognitive impairment in later childhood. A cohort of 131 children from a shantytown community in northeast Brazil was monitored from birth to 24 months for diarrhea and anthropometric status. Cognitive assessments including Test of Nonverbal Intelligence (TONI), coding tasks (WISC-III), and verbal fluency (NEPSY) were completed when children were an average of 8.4 years of age (range = 5.6-12.7 years). Multivariate analysis of variance models were used to assess the individual as well as combined effects of ECD and stunting on later childhood cognitive performance. ECD, height for age (HAZ) at 24 months, and weight for age (WAZ) at 24 months were significant univariate predictors of the studies three cognitive outcomes: TONI, coding, and verbal performance (P < 0.05). Multivariate models showed that ECD remained a significant predictor, after adjusting for the effect of 24 months HAZ and WAZ, for both TONI (HAZ, P = 0.029 and WAZ, P = 0.006) and coding (HAZ, P = 0.025 and WAZ, P = 0.036) scores. WAZ and HAZ were also significant predictors after adjusting for ECD. ECD remained a significant predictor of coding (WISC III) after number of household income was considered (P = 0.006). This study provides evidence that ECD and stunting may have independent effects on children's intellectual function well into later childhood.

Early childhood diarrhea is associated with diminished cognitive function 4 to 7 years later in children in a northeast Brazilian shantytown.

Diarrhea is well recognized as a leading cause of childhood mortality and morbidity in developing countries; however, possible long-term cognitive deficits from heavy diarrhea burdens in early childhood remain poorly defined. To assess the potential long-term impact of early childhood diarrhea (in the first 2 years of life) on cognitive function in later childhood, we studied the cognitive function of a cohort of children in an urban Brazilian shantytown with a high incidence of early childhood diarrhea. Forty-six children (age range, 6-10 years) with complete diarrhea surveillance during their first 2 years of life were given a battery of five cognitive tests. Test of Non-Verbal Intelligence-III (TONI) scores were inversely correlated with early childhood diarrhea (P = .01), even when controlling for maternal education, duration of breast-feeding, and early childhood helminthiasis (Ascaris or Trichuris). Furthermore, Wechsler Intelligence Scale for Children (WISC-III) Coding Tasks and WISC-III Digit Span (reverse and total) scores were also significantly lower in the 17 children with a history of early childhood persistent diarrhea (PD; P < .05), even when controlling for helminths and maternal education. No correlations were seen between diarrhea rates and Wide Range Assessment of Memory and Learning subtests or WISC-III Mazes. This report (with larger numbers of participants and new tests) confirms and substantially extends previous pilot studies, showing that long-term cognitive deficits are associated with early childhood diarrhea. These findings have important implications for the importance of interventions that may reduce early childhood diarrheal illnesses or their consequences.