Aberrant white matter properties of the callosal tracts implicated in girls with attention-deficit/hyperactivity...

Aberrant microstructure of the callosal tracts has been found in boys with attention-deficit/hyperactivity disorder (ADHD). However, it is unclear whether the previously identified white matter (WM) alterations in boys with ADHD are also present in girls with ADHD. Thus, we applied diffusion tensor imaging (DTI) to investigate WM alterations in the callosal tracts in girls with ADHD. In this study, twenty-four adolescent girls (fourteen ADHD patients and ten typically developed girls) were recruited for high-resolution DTI. Automated fiber quantification of the callosum forceps major and the callosum forceps minor was then conducted. Diffusion parameters, including fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD), were calculated to investigate the microstructural integrity of the two callosal tracts. We also investigated correlations between diffusion properties and clinical measurements, including scores on Conners' Parent Rating Scale, the Stroop Color-Word Test, the Wisconsin Card Sorting Test and the Continuous Performance Test, in ADHD patients and typically developed girls. Compared to typically developed adolescent girls, girls with ADHD had reduced FA values at nodes 59-70 and increased RD values at nodes 60-68 along the callosum forceps major. Lower FA values correlated with higher Hyperactivity-Impulsivity scores and lower control quotients, while higher RD values correlated with lower control quotients. This study revealed the disruption of interhemispheric connectivity, particularly across the right side of the occipital CC tract, which might be involved in visual processes in girls with ADHD. These findings enhanced current knowledge about the neuropathological basis of female ADHD.