Breastfeeding and Childhood IQ: The Mediating Role of Gray Matter Volume

doi:10.1016/j.jaac.2016.02.009

Journal of the American Academy of Child & Adolescent Psychiatry

Volume 55, Issue 5, May 2016, Pages 367-375

https://doi.org/10.1016/j.jaac.2016.02.009 Get rights and content

Objective

A substantial body of literature has established the positive effect of breastfeeding on child developmental outcomes. There is increasing consensus that breastfed children have higher IQs after accounting for key variables, including maternal education, IQ, and socioeconomic status. Cross-sectional investigations of the effects of breastfeeding on structural brain development suggest that breastfed infants have larger whole brain, cortical, and white matter volumes. To date, few studies have related these measures of brain structure to IQ in breastfed versus nonbreastfed children in a longitudinal sample.

Method

Data were derived from the Preschool Depression Study (PDS), a prospective longitudinal study in which children and caregivers were assessed annually for 8 waves over 11 years. A subset completed neuroimaging between the ages of 9.5 and 14.11 years. A total of 148 individuals had breastfeeding data at baseline and complete data on all variables of interest, including IQ and structural neuroimaging. General linear models and process mediation models were used.

Results

Breastfed children had significantly higher IQ scores and larger whole brain, total gray matter, total cortical gray matter, and subcortical gray matter volumes compared with the nonbreastfed group in models that covaried for key variables. Subcortical gray matter volume significantly mediated the association between breastfeeding and children’s IQ scores.

Conclusion

The study findings suggest that the effects of breastfeeding on child IQ are mediated through subcortical gray volume. This effect and putative mechanism is of public health significance and further supports the importance of breastfeeding in mental health promotion.

Section snippets

Overview of Study Design and Participants

At baseline (n = 306), children 3.0 to 5.11 years old and their primary caregivers were recruited from daycare, preschool, and primary care sites in the St. Louis area for a study of preschool depression. The sample was ascertained based on child characteristics, and a screening checklist¹⁹ was used to oversample children with early-onset behavioral and emotional symptoms (specifically depression) as well as healthy controls. Children and their caregivers were assessed annually for 8 assessment

Demographic, Developmental, and Clinical Characteristics of the Sample

As seen in Table 1, breastfeeding (yes versus no) was not related to children’s age at scan, sex, gestational age, or birth weight (all p values >.05). Breastfed compared with nonbreastfed children were marginally less likely to have been diagnosed with depression and/or anxiety from baseline up until the time of scan (p = .09). African American children were less likely to have been breastfed compared with children of white and other ethnicities (p < .0001). Breastfed children were more likely

Discussion

These data demonstrate an indirect relationship between breastfeeding and IQ through the development of gray matter volume, specifically subcortical gray matter. The relationship held even after accounting for key variables known to influence IQ, including primary caregiver education, sex, and internalizing diagnoses. Importantly, the effects of breastfeeding on IQ were mediated by subcortical gray matter. To the best of our knowledge, these findings are the first showing a putative mechanistic

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Although it is well established that breastfeeding is an important precursor of key nutrients associated with WM development, we did not find any association of breastfeeding practices and WM maturation in children with overweight/obesity. Likewise, a previous work in a similar age range found that breastfeeding duration was not associated with WM volumes [74], and another work found a significant association between exclusive breastfeeding duration and WM microstructure in boys, but not in girls [75]. Thus, it is possible that obesity is masking the effect of breastfeeding on WM and that the plausible effects of breastfeeding practices are not detectable in childhood.
Exposure to a suboptimal environment during the fetal and early infancy period's results in long-term consequences for brain morphology and function. We investigated the associations of early life factors such as anthropometric neonatal data (i.e., birth length, birth weight and birth head circumference) and breastfeeding practices (i.e., exclusive and any breastfeeding) with white matter (WM) microstructure, and ii) we tested whether WM tracts related to early life factors are associated with academic performance in children with overweight/obesity.
96 overweight/obese children (10.03 ± 1.16 years; 38.7% girls) were included from the ActiveBrains Project. WM microstructure indicators used were fractional anisotropy (FA) and mean diffusivity (MD), derived from Diffusion Tensor Imaging. Academic performance was evaluated with the Battery III Woodcock–Muñoz Tests of Achievement. Regression models were used to examine the associations of the early life factors with tract-specific FA and MD, as well as its association with academic performance.
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Our results highlighted the importance of the perinatal growth in WM microstructure later in life, although its possible academic implications remain inconclusive.
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: This study was funded by National Institute of Mental Health (NIMH) grants R01 MH064769–R01 MH090786.

: The authors thank the study families and participants who have generously committed their time to this longitudinal study.

: Disclosure: Dr. Luby has received grant or research support from NIMH. She has received royalties from Guilford Press. Dr. Barch has served as a consultant for Pfizer, Amgen, Roche, and Takeda, and has a contract to analyze imaging data for Pfizer. She has received grant or research support from the NIMH, the National Institute for Drug Abuse, and the National Institutes of Health (NIH) Blueprint. Drs. Belden, Whalen, and Harms report no biomedical financial interests or potential conflicts of interest.

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New researchBreastfeeding and Childhood IQ: The Mediating Role of Gray Matter Volume

Objective

Method

Results

Conclusion

Section snippets

Overview of Study Design and Participants

Demographic, Developmental, and Clinical Characteristics of the Sample

Discussion

Early Hum Dev

Lancet Global Health

Am J Clin Nutr

Soc Sci Med (1982)

Neuroimage

Neuroimage

Neuroimage

J Am Acad Child Adolesc Psychiatry

J Am Acad Child Adolesc Psychiatry

Neuroimage

Am J Clin Nutr

Evidence on the Long-term Effects of Breastfeeing: Systematic Reviews and Meta-Analyses

Breastfeeding and child cognitive development: new evidence from a large randomized trial

Arch Gen Psychiatry

What are the causal effects of breastfeeding on IQ, obesity and blood pressure? Evidence from comparing high-income with middle-income cohorts

Int J Epidemiol

The association between duration of breastfeeding and adult intelligence

JAMA

Intelligence predicts health and longevity, but why?

Curr Direct Psychol Sci

New research
Breastfeeding and Childhood IQ: The Mediating Role of Gray Matter Volume