Effects of biological and social factors on the cognitive development of very low birth weight children.

Abstract

To investigate the effects of biological and social factors on the cognitive development of very low birth weight children, a longitudinal follow-up study was conducted from birth to 3.6 years of age. The study group consisted of a cohort of 79 surviving high-risk, very low birth weight infants. Neonatal cerebral ultrasonographic findings and a neurological score were used as indicators of biological risk. A sociodemographic risk score and the Home Observation for Measurement of the Environment inventory were used as indicators of social risk. Cognitive development was assessed at ages 1 and 2 years by the Mental scale of the Bayley Scales of Infant Development and at age 3.6 years by the Kaufman Assessment Battery for Children. The mean mental index at 1 year of age was 96 (SD 19), at 2 years of age 86 (SD 26), and at 3.6 years of age for intelligence 87 (SD 13) and for achievement 86 (SD 14). In a stepwise multiple regression analysis of biological as well as social factors, the neurological score alone was the best predictor for cognitive development at 1 year of age, explaining 46% of the variance. From 2 years of age onward, the best predictors for cognitive development were the neurological score together with the home environment, explaining 46% of the variance for the Mental Developmental Index at age 2, 34% for intelligence, and 56% for achievement at age 3.6. Children at high biological risk were able to catch up on their cognitive delay in a highly stimulating home environment. Children at low as well as high biological risk in a less stimulating home environment showed a decline in cognitive development. For these children, early intervention programs might be important in the prevention of cognitive disabilities.