Both groups of infants in the study started with an average of a 5.6 millisecond response time. The decrease over the two weeks was a fraction of this - infants fed breast milk, for example, showed an average of a 0.3 millisecond decrease per week, compared with a decrease of about 0.16 in infants fed formula. Guillet said she is not sure whether her results can carry over to infants born at term. All infants in the study were born at least two months premature. But the study falls in line with previous studies that showed that infants fed breast milk had higher IQs, more fully developed nervous systems, and decreased incidence of SIDS than infants fed formula, she said.
Premature infants are difficult to breast feed because many lack proper motor control.
So infants in this study were fed with breast milk from a bottle. This eliminated any differences in brain development that could be attributed to family contact or interactions with the mother - criticisms leveled against some studies showing the benefits of breast milk. The authors speculate that the critical difference between formula and breast milk could lie in the fat content. Infants appear to have trouble making long chains of fatty acid on their own, Guillet said, and breast milk contains long chains of fatty acids that are missing from formula sold in the United States. Appeared in the Milwaukee Journal Sentinel on Aug. 8, 2000.