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Original Investigation
December 9, 2019

Associations Among Body Mass Index, Cortical Thickness, and Executive Function in Children

Author Affiliations
  • 1Department of Nursing, College of Nursing and Health Sciences, University of Vermont, Burlington
  • 2Magnetic Resonance Imaging Facility, Yale University, New Haven, Connecticut
  • 3Department of Psychiatry, Larner College of Medicine, University of Vermont, Burlington
JAMA Pediatr. Published online December 9, 2019. doi:10.1001/jamapediatrics.2019.4708
Key Points

Questions  Is body mass index associated with cortical thickness in 9- and 10-year-old children, and does this association interact with executive functioning?

Findings  In this cross-sectional study, higher body mass index was associated with thinner cortex, especially in the prefrontal cortex. The association between body mass index and working memory was partially mediated by prefrontal cortex thickness.

Meaning  These findings suggest that body mass index is associated with cortical development and diminished executive functions, such as working memory.

Abstract

Importance  A total of 25.7 million children in the United States are classified as overweight or obese. Obesity is associated with deficits in executive function, which may contribute to poor dietary decision-making. Less is known about the associations between being overweight or obese and brain development.

Objective  To examine whether body mass index (BMI) is associated with thickness of the cerebral cortex and whether cortical thickness mediates the association between BMI and executive function in children.

Design, Setting, and Participants  In this cross-sectional study, cortical thickness maps were derived from T1-weighted structural magnetic resonance images of a large, diverse sample of 9 and 10-year-old children from 21 US sites. List sorting, flanker, matrix reasoning, and Wisconsin card sorting tasks were used to assess executive function.

Main Outcomes and Measures  A 10-fold nested cross-validation general linear model was used to assess mean cortical thickness from BMI across cortical brain regions. Associations between BMI and executive function were explored with Pearson partial correlations. Mediation analysis examined whether mean prefrontal cortex thickness mediated the association between BMI and executive function.

Results  Among 3190 individuals (mean [SD] age, 10.0 [0.61] years; 1627 [51.0%] male), those with higher BMI exhibited lower cortical thickness. Eighteen cortical regions were significantly inversely associated with BMI. The greatest correlations were observed in the prefrontal cortex. The BMI was inversely correlated with dimensional card sorting (r = −0.088, P < .001), list sorting (r = −0.061, P < .003), and matrix reasoning (r = −0.095, P < .001) but not the flanker task. Mean prefrontal cortex thickness mediated the association between BMI and list sorting (mean [SE] indirect effect, 0.014 [0.008]; 95% CI, 0.001-0.031) but not the matrix reasoning or card sorting task.

Conclusions and Relevance  These results suggest that BMI is associated with prefrontal cortex development and diminished executive functions, such as working memory.

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    2 Comments for this article
    Got it backwards
    Henry Skinner, MD | Family Psychiatry of Maine
    Lovely demonstration of association between adiposity and executive function. Application of Occam's razor might reveal that the directionality of the association makes much more sense and would yield much more clinical and population health utility if reversed. People with executive function challenges have more difficulty negotiating the toxic capitalist nutrition environment, resulting in increased adiposity and a host of downstream health challenges. Child and adolescent psychiatrists observe this in clinic frequently.
    CONFLICT OF INTEREST: None Reported
    Did study control for computer/ cell phone gaming and other online addictions?
    Jim Carmine, PhD | Carlow University
    It seems likely there are confounding variables that have been overlooked. Obese children tend to have gaming addictions, and so rarely exercise as they ought. Perhaps that is what we are seeing. Not obesity leading to cognitive impairment but computer addiction leading to cognitive impairment coupled with obesity.
    CONFLICT OF INTEREST: None Reported
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