Objective: Breastfeeding during infancy is associated with a lower risk of attention-deficit/hyperactivity disorder (ADHD). Although this is presumably due to breast milk's nutritional advantages, formula-fed infants have, until recently, also been exposed to bisphenol A (BPA), a neurotoxic chemical previously used to manufacture baby bottles and formula cans. Our goal was to examine the association between formula feeding and preschool ADHD in 2 comparable, serial cohorts of preschool children who differ in BPA exposure during infancy.
Methods: Cross-sectional analysis of the 2007 and 2011/12 National Survey of Children's Health (NSCH). Logistic regression was used to model preschool ADHD diagnoses as a function of breastfeeding, adjusting for 12 possible confounding variables using a propensity score.
Results: In the 2007 data set (weighted n = 9,644,405), formula-fed subjects had a 5-fold increased odds of ADHD compared with breastfed subjects (adjusted odds ratio [aOR]: 5.58, 95% confidence interval [CI], 2.16-14.41). In the 2011/12 data set (n = 9,732,865), there was no significant association between formula feeding and later ADHD (aOR: 1.05, 95% CI, 0.42-2.64). This is despite an increase in the prevalence of preschool ADHD in 2011 (0.88%) compared with 2007 (0.40%) (Rao-Scott χ, p < .0075).
Conclusion: Compared with breastfed infants, ADHD was more common among formula-fed infants in the 2007 but not the 2011/12 sample, where exposure to BPA was markedly reduced. These findings suggest that the reduced prevalence of ADHD among breastfed infants may not be due to the nutritional benefits of breast milk, but rather early exposure to BPA, a neurotoxic chemical previously found in infant formula.