Breastfeeding and cognitive development

[Breastfeeding: health benefits for child and mother]

The prevalence of breastfeeding in France is one of the lowest in Europe: 65% of infants born in France in 2010 were breastfed when leaving the maternity ward. Exclusive breastfeeding allows normal growth until at least 6 months of age, and can be prolonged until the age of 2 years or more, provided that complementary feeding is started after 6 months. Breast milk contains hormones, growth factors, cytokines, immunocompetent cells, etc., and has many biological properties. The composition of breast milk is influenced by gestational and postnatal age, as well as by the moment of the feed. Breastfeeding is associated with slightly enhanced performance on tests of cognitive development. Exclusive breastfeeding for at least 3 months is associated with a lower incidence and severity of diarrhoea, otitis media and respiratory infection. Exclusive breastfeeding for at least 4 months is associated with a lower incidence of allergic disease (asthma, atopic dermatitis) during the first 2 to 3 years of life in at-risk infants (infants with at least one first-degree relative presenting with allergy). Breastfeeding is also associated with a lower incidence of obesity during childhood and adolescence, as well as with a lower blood pressure and cholesterolemia in adulthood. However, no beneficial effect of breastfeeding on cardiovascular morbidity and mortality has been shown. Maternal infection with hepatitis B and C virus is not a contraindication to breastfeeding, as opposed to HIV infection and galactosemia. A supplementation with vitamin D and K is necessary in the breastfed infant. Very few medications contraindicate breastfeeding. Premature babies can be breastfed and/or receive mother's milk and/or bank milk, provided they receive energy, protein and mineral supplements. Return to prepregnancy weight is earlier in breastfeeding mothers during the 6 months following delivery. Breastfeeding is also associated with a decreased risk of breast and ovarian cancer in the premenopausal period, and of osteoporosis in the postmenopausal period.

The Relationship between Nutrition in Infancy and Cognitive Performance during Adolescence

OBJECTIVES

In this study, we aimed to investigate the long-term associations between breastfeeding duration during infancy, diet quality as measured by a diet score at 1 year of age, and cognitive performance during adolescence.

METHODS

Participants (n = 717) were recruited from the West Australian Pregnancy Cohort (Raine) Study, a prospective longitudinal study of 2868 children and their families based in Perth, WA, Australia. Breastfeeding duration and an early diet score at age 1 year were used as the main predictor variables, while a computerized cognitive battery (CogState) was used to assess adolescents' cognitive performance at 17 years. The diet score, which has seven food group components, was based on a 24-h recall questionnaire completed by the mother at 1 year of age. A higher diet score represents a better, more nutritious eating pattern. Associations between breastfeeding duration, diet score, and cognitive performance were assessed in multivariable regression models.

RESULTS

Higher diet scores at 1 year representing better diet quality were significantly associated with faster reaction times in cognitive performance at 17 years [Detection Task (DET): β = -0.004, 95% CI: -0.008; 0.000, p = 0.036; Identification Task (IDN): β = -0.004, 95% CI: -0.008; 0.000, p = 0.027]. Breastfeeding duration (≥4 months) was also significantly associated with a shorter reaction time, but only for males (DET: β = -0.026, 95% CI: -0.046; -0.006, p = 0.010).

CONCLUSION

Nutrition in early childhood may have a long-term association with fundamental cognitive processing speed, which is likely to be related to enhanced brain development in the first year of life.

The effect of breastfeeding on neuro-development in infancy

The present study examines whether breastfeeding is associated with neuro-developmental advantages at 9 months of age on a standardised measure of infant development in a large cohort study of Irish children. It is hypothesised that if breast-milk confers an independent benefit, infants who were never breastfed will have reached fewer developmental milestones than those who were partially or exclusively breastfed, after controlling for putative confounding variables. Families with infants aged 9-months were recruited as part of a nationally representative sample for the birth cohort of the Growing Up in Ireland study (n = 11,134). Information was collected from mothers on breastfeeding practices, socio-demographic characteristics and developmental progress during a household interview. Parent-report items on development covered communication, gross motor, fine motor, problem solving and personal-social skills. Analysis of pass/fail status in each developmental domain using binary logistic regression showed a positive effect of any breastfeeding on gross motor, fine motor, problem solving and personal-social skills (but not communication) and these remained after adjustment for a range of confounding variables. There was, however, little evidence of a dose-response effect or advantage of exclusive over partial breastfeeding. A clear advantage of breastfeeding on infant development was demonstrated. However, the lack of a dose-response association on pass rates suggests that the breastfeeding effect may be confounded by other unobserved factors or that there is a critical threshold during which time the effect of breast milk may be particularly salient for bolstering brain development.

A cohort study on full breastfeeding and child neuropsychological development: the role of maternal social, psychological, and nutritional factors

AIM

This study investigated whether duration of full breastfeeding is associated with child neuropsychological development and whether this association is explained by social, psychological, and nutritional factors within families.

METHOD

Participants in this study were a population-based birth cohort in the city of Sabadell (Catalonia, Spain). Females were recruited during the first trimester of pregnancy between July 2004 and July 2006. Information about parental characteristics and breastfeeding was obtained through questionnaires. Full breastfeeding was categorized as never, short term (≤4mo), long term (4-6mo), or very long term (>6mo). A trained psychologist assessed the neuropsychological development of children at 4 years of age (n=434) using the McCarthy Scales of Children's Abilities (MSCA).

RESULTS

Full breastfeeding showed an independent association with child general MSCA scores after adjusting for a range of social, psychological, and nutritional factors (>6mo, coefficient=7.4 [95% confidence interval=2.8-12.0], p=0.011). Maternal social class, education level, and IQ were also associated with child neuropsychological scores, but did not explain breastfeeding associations. Omega-3 (n3) fatty acid levels were not associated with child neuropsychological scores.

INTERPRETATION

Very long-term full breastfeeding was independently associated with neuropsychological functions of children at 4 years of age. Maternal indicators of intelligence, psychopathology, and colostrum n3 fatty acids did not explain this association.

Is breast truly best? Estimating the effects of breastfeeding on long-term child health and wellbeing in the United States using sibling comparisons

Breastfeeding rates in the U.S. are socially patterned. Previous research has documented startling racial and socioeconomic disparities in infant feeding practices. However, much of the empirical evidence regarding the effects of breastfeeding on long-term child health and wellbeing does not adequately address the high degree of selection into breastfeeding. To address this important shortcoming, we employ sibling comparisons in conjunction with 25 years of panel data from the National Longitudinal Survey of Youth (NLSY) to approximate a natural experiment and more accurately estimate what a particular child's outcome would be if he/she had been differently fed during infancy. Results from standard multiple regression models suggest that children aged 4 to 14 who were breast- as opposed to bottle-fed did significantly better on 10 of the 11 outcomes studied. Once we restrict analyses to siblings and incorporate within-family fixed effects, estimates of the association between breastfeeding and all but one indicator of child health and wellbeing dramatically decrease and fail to maintain statistical significance. Our results suggest that much of the beneficial long-term effects typically attributed to breastfeeding, per se, may primarily be due to selection pressures into infant feeding practices along key demographic characteristics such as race and socioeconomic status.

Breastfeeding and early white matter development: A cross-sectional study

Does breastfeeding alter early brain development? The prevailing consensus from large epidemiological studies posits that early exclusive breastfeeding is associated with improved measures of IQ and cognitive functioning in later childhood and adolescence. Prior morphometric brain imaging studies support these findings, revealing increased white matter and sub-cortical gray matter volume, and parietal lobe cortical thickness, associated with IQ, in adolescents who were breastfed as infants compared to those who were exclusively formula-fed. Yet it remains unknown when these structural differences first manifest and when developmental differences that predict later performance improvements can be detected. In this study, we used quiet magnetic resonance imaging (MRI) scans to compare measures of white matter microstructure (mcDESPOT measures of myelin water fraction) in 133 healthy children from 10 months through 4 years of age, who were either exclusively breastfed a minimum of 3 months; exclusively formula-fed; or received a mixture of breast milk and formula. We also examined the relationship between breastfeeding duration and white matter microstructure. Breastfed children exhibited increased white matter development in later maturing frontal and association brain regions. Positive relationships between white matter microstructure and breastfeeding duration are also exhibited in several brain regions, that are anatomically consistent with observed improvements in cognitive and behavioral performance measures. While the mechanisms underlying these structural differences remains unclear, our findings provide new insight into the earliest developmental advantages associated with breastfeeding, and support the hypothesis that breast milk constituents promote healthy neural growth and white matter development.

The role of nutrition in children's neurocognitive development, from pregnancy through childhood

This review examines the current evidence for a possible connection between nutritional intake (including micronutrients and whole diet) and neurocognitive development in childhood. Earlier studies which have investigated the association between nutrition and cognitive development have focused on individual micronutrients, including omega-3 fatty acids, vitamin B12, folic acid, choline, iron, iodine, and zinc, and single aspects of diet. The research evidence from observational studies suggests that micronutrients may play an important role in the cognitive development of children. However, the results of intervention trials utilizing single micronutrients are inconclusive. More generally, there is evidence that malnutrition can impair cognitive development, whilst breastfeeding appears to be beneficial for cognition. Eating breakfast is also beneficial for cognition. In contrast, there is currently inconclusive evidence regarding the association between obesity and cognition. Since individuals consume combinations of foods, more recently researchers have become interested in the cognitive impact of diet as a composite measure. Only a few studies to date have investigated the associations between dietary patterns and cognitive development. In future research, more well designed intervention trials are needed, with special consideration given to the interactive effects of nutrients.

Prenatal-onset neurodevelopmental disorders secondary to toxins, nutritional deficiencies, and maternal illness

Neurodevelopmental disorders result from an inordinate number of genetic and environmental causes during the embryological and fetal periods of life. In the clinical setting, deciphering precise etiological diagnoses is often difficult. Newer screening technologies allow a gradual shift from traditional nature-versus-nurture debates toward the focused analysis of gene-by-environment interactions (G X E). Further understanding of developmental adaptation and plasticity requires consideration of epigenetic processes such as maternal nutritional status, environmental toxins, maternal illnesses, as well as genetic determinants, alone or in combination. Appreciation of specific G X E mechanisms of neurodevelopmental pathogenesis should lead to better risk-modifying or preventive strategies. We provide a brief overview of clinical and experimental observations that link prenatal-onset toxic exposures, metabolic disturbances, and maternal illnesses to certain neurodevelopmental disorders.

Breastfeeding and the child cognitive outcomes: a propensity score matching approach

To estimate the effect of breastfeeding initiation and duration on child development outcomes. 3,271 children and their mothers participating in the Child Development Supplement of the Panel Study of Income Dynamics provide data for these analyses. Main outcomes include Woodcock Johnson Psycho-Educational Battery-Revised (WJ-R) test score (letter word, passage comprehension, applied problem, and broad reading), and Wechsler Intelligence Scale for Children-Revised (WISC-R) test score at the 2002 survey. Controlled variables include family, maternal, and child characteristics, many of which can be traced back to the year the child was born. The analytic technique is propensity score matching with multiple imputations. After using propensity scores to adjust for confounding factors, breastfeeding initiation showed statistically significant effects but the practical scale remains small. Breastfeeding duration showed a non-linear effect on those outcomes and most of the effects are not significant. The effects of breastfeeding on child's cognitive outcomes are modest in practical terms. The non-linear effects suggest that selection into breastfeeding may account for the increased score of children who are breastfed.

Cortical responses to speech sounds in 3- and 6-month-old infants fed breast milk, milk formula, or soy formula

Controversy exists about the safety of soy formula, with the main concern relating to potential estrogenic effects of soy protein. Since estrogens influence early brain development, we compared behavioral development and cortical responses (event-related potentials; ERPs) to speech sounds in infants fed either breast milk or formula (milk- or soy-based). Across-groups ERP measures were generally similar and behavioral measures were within normal ranges, suggesting no important influences of soy formula on behavioral development and brain function during the study period. Analyses relating ERP and behavioral measures revealed diet- and gender-specific emphases that may reflect differences in developmental trajectories of brain-behavior relationships.

Breast feeding and mental and motor development at 12 months in a low-income population in northeast Brazil

The aim of this prospective study was to investigate the association between breast feeding and mental and motor development at age 12 months, controlling for comprehensive measures of the child's socio-economic, maternal and environmental background, and nutritional status. A cohort of 205 infants born during May-August 2001 in a poor area in the interior of the State of Pernambuco was enrolled, of whom 191 were tested at age 12 months with the Bayley Scales of Infant Development II, and in whom breast-feeding status was measured at days 1, 10, 30, 60, 90, 120, 150, 180, 270 and 360. After adjusting for potential confounders, full breast feeding (i.e. exclusive or predominant) at 1 month was associated with a small but significant benefit in mental development (+3.0 points, P = 0.02) compared with partial or no breast feeding. No additional advantage in mental development was found with longer durations of full breast feeding. Full breast feeding at 1 month was associated with improved behaviour for two of 10 ratings tested: initiative with tasks (P = 0.003) and attention (P = 0.02). No association between breast feeding and motor development was found.

Effect of breast feeding on intelligence in children: prospective study, sibling pairs analysis, and meta-analysis

OBJECTIVE

To assess the importance of maternal intelligence, and the effect of controlling for it and other important confounders, in the link between breast feeding and children's intelligence.

DESIGN

Examination of the effect of breast feeding on cognitive ability and the impact of a range of potential confounders, in particular maternal IQ, within a national database. Additional analyses compared pairs of siblings from the sample who were and were not breast fed. The results are considered in the context of other studies that have also controlled for parental intelligence via meta-analysis.

SETTING

1979 US national longitudinal survey of youth.

SUBJECTS

Data on 5475 children, the offspring of 3161 mothers in the longitudinal survey.

MAIN OUTCOME MEASURE

IQ in children measured by Peabody individual achievement test.

RESULTS

The mother's IQ was more highly predictive of breastfeeding status than were her race, education, age, poverty status, smoking, the home environment, or the child's birth weight or birth order. One standard deviation advantage in maternal IQ more than doubled the odds of breast feeding. Before adjustment, breast feeding was associated with an increase of around 4 points in mental ability. Adjustment for maternal intelligence accounted for most of this effect. When fully adjusted for a range of relevant confounders, the effect was small (0.52) and non-significant (95% confidence interval -0.19 to 1.23). The results of the sibling comparisons and meta-analysis corroborated these findings.

CONCLUSIONS

Breast feeding has little or no effect on intelligence in children. While breast feeding has many advantages for the child and mother, enhancement of the child's intelligence is unlikely to be among them.

Breastfeeding and verbal ability of 3-year-olds in a multicity sample

OBJECTIVES

Our goal was to analyze the effect of maternal verbal ability and education on the association between breastfeeding and children's cognitive functioning. First, we hypothesized that maternal verbal abilities account for a large portion of the association between breastfeeding and child verbal abilities. Second, we hypothesized that after adjusting for maternal verbal abilities, a positive effect of breastfeeding will be most evident among highly educated mothers, because these mothers may have more opportunity to engage in cognitively stimulating parenting than do mothers with less education.

PATIENTS AND METHODS

With data on 1645 American-born mothers participating in a longitudinal birth cohort study, we used linear regression to determine the influence of breastfeeding for at least 1 month on the Peabody Picture Vocabulary Test-Third Edition scores of 3-year-old children. Models were adjusted for an extensive set of demographic characteristics, including mother's Peabody Picture Vocabulary Test and the Home Observation for Measurement of the Environment score. Mothers were categorized into 1 of 3 educational-status groups: no high school diploma, high school diploma, and some post-secondary education.

RESULTS

In unadjusted mean comparisons, breastfed children had Peabody Picture Vocabulary Test scores that were 6.6 points higher than children who were not breastfed. After adjusting for demographic characteristics and maternal verbal ability, the coefficient dropped to 1.72. Among mothers with education beyond high school, the children's Peabody Picture Vocabulary Test scores in adjusted models were 2.2 points higher for breastfed children. Among mothers with a high school diploma or less, there were no significant differences in the children's Peabody Picture Vocabulary Test scores by breastfeeding status. These results were consistent in white, black, and Hispanic children.

CONCLUSIONS

Maternal Peabody Picture Vocabulary Test scores mediate much of the association between breastfeeding and child verbal abilities. The beneficial effects of breastfeeding on children's cognition may emerge only when breastfeeding is done in conjunction with other positive parenting behaviors. The advantageous effects of breastfeeding do not seem to be solely attributable to the superior nutrient content of breast milk.

Is docosahexaenoic acid, an n-3 long-chain polyunsaturated fatty acid, required for development of normal brain function? An overview of evidence from cognitive and behavioral tests in humans and animals

This review is part of a series intended for nonspecialists that will summarize evidence relevant to the question of whether causal relations exist between micronutrient deficiencies and brain function. Here, we focus on experiments that used cognitive or behavioral tests as outcome measures in experimental designs that were known to or were likely to result in altered brain concentrations of the n-3 fatty acid docosahexaenoic acid (DHA) during the perinatal period of "brain growth spurt." Experimental designs reviewed include observational breastfeeding studies and randomized controlled trials in humans and studies in rodents and nonhuman primates. This review is based on a large number of expert reviews and commentaries and on some 50 recent studies in humans and animals that have not yet been included in published reviews. Expert opinion regarding the strengths and weaknesses of the major experimental systems and uncertainties associated with interpreting results is summarized. On the basis of our reading of this literature, we conclude that evidence from several types of studies, particularly studies in animals, suggests that, within the context of specific experimental designs, changes in brain concentrations of DHA are positively associated with changes in cognitive or behavioral performance. Additional experimental information required to conclude that a causal association exists is discussed, as are uncertainties associated with applying results from specific experimental designs to the question of whether infant formula should be supplemented with DHA.