Contributions of Cerebellar White Matter Microstructure to Social Difficulty in Nonverbal Learning Disability

Abstract

Emerging evidence suggests that the cerebellum may contribute to variety of cognitive capacities, including social cognition. Nonverbal learning disability (NVLD) is characterized by visual-spatial and social impairment. Recent functional neuroimaging studies have shown that children with NVLD have altered cerebellar resting-state functional connectivity, which is associated with various symptom domains. However, little is known about cerebellar white matter microstructure in NVLD and whether it contributes to social deficits. Twenty-seven children (12 with NVLD, 15 typically developing (TD)) contributed useable diffusion tensor imaging data. Tract-based spatial statistics (TBSS) were used to quantify fractional anisotropy (FA) in the cerebellar peduncles. Parents completed the Child Behavior Checklist, providing a measure of social difficulty. Children with NVLD had greater fractional anisotropy in the left and right inferior cerebellar peduncle. Furthermore, right inferior cerebellar peduncle FA was associated with social impairment as measured by the Child Behavior Checklist Social Problems subscale. Finally, the association between NVLD diagnosis and greater social impairment was mediated by right inferior cerebellar peduncle FA. These findings provide additional evidence that the cerebellum contributes both to social cognition and to the pathophysiology of NVLD.

Keywords: Cerebellum; Diffusion tensor imaging; Neurodevelopment; Neuroimaging; Nonverbal learning disability.

Figure 1.

Relative to TD children, children with NVLD had higher FA in the A) left and B) right inferior cerebellar peduncles. Gray points depict group means. FA = fractional anisotropy. NVLD = Nonverbal Learning Disability. TD = typically developing.

Figure 2.

Right inferior cerebellar peduncle (RICP) fractional anisotropy (FA) A) was positively associated with CBCL Total Problems, residualized for age and diagnostic group (NVLD vs. typically developing) and B) mediated the association between NVLD diagnosis and CBCL Total Problems. The regression coefficient a relates NVLD diagnosis to RICP FA, and the regression coefficient b relates RICP FA to CBCL Social Problems, controlling for NVLD diagnosis. The total effect is defined as the regression coefficient relating NVLD diagnosis to CBCL Social Problems; the direct effect is defined as the regression coefficient relating NVLD diagnosis to CBCL Social Problems, controlling for the effects of RICP FA. *p<.05, **p<.01, ***p<.001. CBCL= Child Behavior Checklist. NVLD = nonverbal learning disability.