Cognitive functions correlate with white matter architecture in a normal pediatric population: a diffusion tensor MRI study

Abstract

A possible relationship between cognitive abilities and white matter structure as assessed by magnetic resonance diffusion tensor imaging (DTI) was investigated in the pediatric population. DTI was performed on 47 normal children ages 5-18. Using a voxelwise analysis technique, the fractional anisotropy (FA) and mean diffusivity (MD) were tested for significant correlations with Wechsler full-scale IQ scores, with subject age and gender used as covariates. Regions displaying significant positive correlations of IQ scores with FA were found bilaterally in white matter association areas, including frontal and occipito-parietal areas. No regions were found exhibiting correlations of IQ with MD except for one frontal area significantly overlapping a region containing a significant correlation with FA. The positive direction of the correlation with FA is the same as that found previously with age, and indicates a positive relationship between fiber organization and/or density with cognitive function. The results are consistent with the hypothesis that regionally specific increased fiber organization is a mechanism responsible for the normal development of white matter tracts.

Figure 1

Regions of statistically significant positive correlations of FA with Full‐Scale IQ, controlling for age and gender, overlaid on the averaged whole‐brain anatomical dataset (slice range Z = +5 mm to +45 mm). Colored voxels have double‐tailed P < 0.05 (corrected). All images in radiological orientation.

Figure 2

Sagittal view containing regions of statistically significant positive correlations of FA with Full‐Scale IQ, controlling for age and gender, overlaid on the averaged whole‐brain anatomical dataset (slice position, x = −32 mm (left); +32 mm (right)), displaying positive correlations of FA with IQ in the arcuate fasciculus bilaterally. Colored voxels have double‐tailed P < 0.05 (corrected).

Figure 3

Regions of statistically significant negative correlations of MD with Full‐Scale IQ, controlling for age and gender, overlaid on the averaged whole‐brain anatomical dataset (slice range Z = +5 mm to +45 mm). Colored voxels have double‐tailed P < 0.05 (corrected). All images in radiological orientation.

Figure 4

Mean FA (y‐axis) as a function of Full‐Scale IQ (x axis) for all regions shown in Table II.