The alteration of gray matter volume in children with mental retardation: the differences between the patients presented with operation deficit predominantly and those presented with language deficit mainly

Objective: To detect the differences of grey matter volume between the patients with mental retardation (MR) presented clinically as operation deficit (OD) or as language deficit (LD) and the children with typical normal development using optimal VBM. The developmental connections between brain gray matter and language or operation skills were examined. Methods: Magnetic resonance imaging was obtained from 9 children with mental retardation presented as OD predominantly and 11 children with mental retardation presented as LD mainly, as well as the age-matched control group (11 and 14 normal children,respectively) on a 1.5 T scanner. Voxel-based morphometry analysis with an optimization of spatial segmentation and normalization procedures was applied to compare the volume of grey matter between the two groups (OD VS.control; LD VS.control). Statistically, the total and local gray matter volumes were compared between the two groups with t test. Results: The total gray matter volume of OD group was [(1.030 ± 0.078) × 10⁶ mm³]. Compared to that of controls [(0.984 ± 0.058) × 10⁶ mm³], it was increased significantly (t=-2.6, P<0.05). And the gray matter volume in the posterior cingulated gyrus, left superior prefrontal gyrus, left cuneus, left middle prefrontal gyrus and the body of left caudate nucleus showed significantly increased. Meanwhile, the total gray matter volume of the MR children presented as LD [(1.002 ± 0.068) × 10⁶ mm³] showed significantly increased(t=-3.0, P<0.05) compared with that of control group [(0.957 ±0.057) × 10⁶ mm³]. The gray matter volume in bilateral thalami, the left inferior temporal gyrus,the left inferior frontal gyrus, and the left cerebellum of the LD group was more than that of normal children. Conclusion: As revealed by VBM, there are differences in alterations of gray matter volume between MR children presented with OD and with LD relative to control. (authors)