Preliminary evidence of cognitive and brain abnormalities in uncomplicated adolescent obesity

Abstract

Objective: To ascertain whether pediatric obesity without clinically significant insulin resistance (IR) impacts brain structure and function.

Methods: Thirty obese and 30 matched lean adolescents, all without clinically significant IR or a diagnosis of metabolic syndrome (MetS), received comprehensive endocrine, neuropsychological, and MRI evaluations.

Results: Relative to lean adolescents, obese non-IR adolescents had significantly lower academic achievement (i.e., arithmetic and spelling) and tended to score lower on working memory, attention, psychomotor efficiency, and mental flexibility. In line with our prior work on adolescent MetS, memory was unaffected in uncomplicated obesity. Reductions in the thickness of the orbitofrontal and anterior cingulate cortices as well as reductions of microstructural integrity in major white matter tracts without gross volume changes were also uncovered.

Conclusions: It was documented, for the first time, that adolescents with uncomplicated obesity already have subtle brain alterations and lower performance in selective cognitive domains. When interpreting these preliminary data in the context of our prior reports of similar, but more extensive brain findings in obese adolescents with MetS and T2DM, it was concluded that "uncomplicated" obesity may also result in subtle brain alterations, suggesting a possible dose effect with more severe metabolic dysregulation giving rise to greater abnormalities.

Figure 1

Six of the seven clusters demonstrating significant FA group differences are displayed in order of cluster size (VANCOVA analysis controlling for age; minimum cluster size of 100 voxels; P<0.005; clusters in blue represent FA reductions in obese adolescents whereas positive associations in yellow represent FA elevation). Each column shows three orthogonal orientations of the average normalized structural image illustrating a significant cluster with the axes passing through the centroid of the cluster. The largest cluster, found in the left temporal stem, was the only one that remained significant at a more conservative P-vlaue threshold of 0.001.