Brain gray and white matter differences in healthy normal weight and obese children

Purpose To compare brain gray and white matter development in healthy normal weight and obese children. Methods Twenty‐four healthy 8‐ to 10‐year‐old children whose body mass index was either <75 th percentile (normal weight) or >95 th percentile (obese) completed an MRI examination which included T1‐weighted three‐dimensional structural imaging and diffusion tensor imaging (DTI). Voxel‐based morphometry was used to compare the regional gray and white matter between the normal weight and obese children, and tract‐based spatial statistics was used to compare the water diffusion parameters in the white matter between groups. Results Compared with normal weight children, obese children had significant ( P  < 0.05, family wise error corrected) regional gray matter reduction in the right middle temporal gyrus, left and right thalami, left superior parietal gyrus, left pre/postcentral gyri, and left cerebellum. Obese children also had higher white matter ( P  < 0.05, corrected) in multiple regions in the brain and higher DTI measured fractional anisotropy (FA) values ( P  < 0.05, corrected) in part of the left brain association and projection fibers. There was no difference in mean diffusivity at P  < 0.05, corrected. DTI eigenvalues suggested that the FA differences were likely from decreased radial diffusivity ( P  < 0.1, corrected) and there was no change in axial diffusivity (corrected P  > 0.35 for all voxels). Conclusion Our results indicated that obese but otherwise healthy children have different regional gray and white matter development in the brain and differences in white matter microstructures compared with healthy normal weight children. J. Magn. Reson. Imaging 2015;42:1205–1213.