Investigation of thealteration of gray matter volume in children with mental retardation with the optimalvoxel-based morphometry

Abstract

：Objective To detectbrain structural difference between children with unexplained mental retardation andchildren with typically normal development. Methods The high-resolution magnetic MRimaging were obtained from 21 children with unexplained mental retardation and 30age-matched control children without intellectual disabilities. Voxel-based morphometryanalysis with an optimization of spatial segmentation and normalization procedures wereapplied to compare differences of gray matter volume between the two groups. The total andregional gray matter volume were compared between the two groups with independent t test.Meanwhile, correlation was conducted to analyze the relationship between the total graymatter volume and intelligence quotient (IQ) with partial correlation test. Results Thetotal gray matter volume was significantly increased in the mental retardation children[(1. 012 ±0. 079) × 106 mm3]in relative to the controls [(0. 956 ± 0. 059) × 106 mm3,t = - 2. 80, P ＜ 0. 05]. Compared tocontrols,children with unexplained mental retardation showed significantly increased graymatter volume in different regions, including the bilateral thalami, the bilateralsuperior frontal gyri, the bilateral gyri rectus, the bilateral temporal poles, the rightinferior frontal gyrus, right parahippocampal gyrus and the right cerebellum. Nocorrelation was detected between the total gray matter volume and IQ in children withmental retardation (r = 0. 078 ,P ＞ 0. 05). Conclusions VBM would detect the gray matterabnormalities that were not founded in routine MR scanning. The increase of gray mattervolume in the frontal-thalamus network might indicate the delayed maturation of the braindevelopment. This might be one of the causations of mental retardation in children. Key words: Mental retardation; Magnetic resonance imaging; Brain; Child