Despite the burgeoning literature documenting the effects of breast-feeding on cognition and educational attainment over the past several decades, there remains important gaps in our knowledge regarding whether this relationship is dictated by sociodemographic factors. The current investigations, which examined the literature on the effects of breast-feeding on cognition and educational attainment in children, adolescents, and older adults addressed these gaps. Chapter 2 was an up-to-date global systematic review of population studies in individuals ≤ 25 years and ≥ 25 years of age. Results indicate that the majority of published studies conducted by researchers demonstrated a positive relationship between the effect of breast-feeding on cognitive outcomes and educational attainment. Additionally, findings highlighted the importance of possible confounders and how adjusting for them can change the relationship between breast-feeding and cognition and educational attainment. Chapter 3 investigated the breast-feeding-cognition/educational attainment relationship across race, as well as whether mother-child stimulation might mediate this relationship.
The National Longitudinal Study of Adolescent to Adult Health (Add Health) was used to examine the effect of being breast-fed or not, and duration on cognitive outcomes and grade point average (GPA). Results indicate that individuals who were breast-fed had slightly higher GPAs and performance on both a vocabulary test and a number recall test compared to adolescents who were not breast-fed. There was an effect for race, but no interaction between race and breast-feeding. Mother-child stimulation had a limited effect on the relationship between breast-feeding and cognitive outcomes and GPA. Chapter 4 explored whether the effect observed in adolescence persists into older adulthood. The Reasons for Geographic and Racial Differences in Stroke (REGARDS) Cohort was used to examine this relationship in adults age ≥ 45 years. The covariates included sex of adolescent, race (Black or White), maternal education, paternal education, maternal smoking history, number of other children mother has, resident location (urban/not-urban), and a financial adversity index.
This was a composite score consisting of yes or no responses to (1) do you have health insurance, (2) have you been employed within the past 12 months, (3) are you on public assistance, and (4) do you have enough money to pay your bills? Results show that self-report history of being breast-fed did not current predict performance on cognitive tests. Additionally, neither race nor sex moderated this relationship between breast-feeding and cognition. Overall, evidence from the review and two studies highlight the important of assessing the effect of breast-feeding on cognition and educational attainment in populations with varying confounding factors, however, while some of the results are inconsistent with our hypothesis, replication is clearly essential to further explore the possible underlying mechanism.
