Determinants of early cognitive development: hierarchical analysis of a longitudinal study

The study describes the relationship between anthropometric status, socioeconomic conditions, and quality of home environment and child cognitive development in 320 children from 20 to 42 months of age, randomly selected from 20,000 households that represent the range of socioeconomic and environmental conditions in Salvador, Bahia, Northeast Brazil. The inclusion criterion was to be less than 42 months of age between January and July 1999. Child cognitive development was assessed using the Bayley Scales for Infant Development, and the Home Observation for Measurement of the Environment Inventory (HOME) was applied to assess quality of home environment. Anthropometric status was measured using the indicators weight/age and height/age ratios (z-scores), and socioeconomic data were collected through a standard questionnaire. Statistical analysis was conducted through univariate and hierarchical linear regression. Socioeconomic factors were found to have an indirect impact on early cognitive development mediated by the child's proximal environment factors, such as appropriate play materials and games available and school attendance. No independent association was seen between nutritional status and early cognitive development.