Microstructural white matter abnormalities of the corpus callosum, as measured by diffusion tensor imaging (DTI), may contribute to Parkinson disease (PD) cognitive impairment by disrupting information transfer across interhemispheric and callosal-cortical projections. This according to a recent study that sought to evaluate microstructural characteristics of the corpus callosum using DTI and their relationships to cognitive impairment in PD. 75 participants with PD and 24 healthy controls (HCs) underwent structural MRI brain scans including DTI sequences and clinical and neuropsychological evaluations. Using Movement Disorder Society criteria, PD participants were classified as having normal cognition (PD-NC, n=23), mild cognitive impairment (PD-MCI, n=35), or dementia (PDD, n=17). Researchers found:
- Participants with PD showed increased axial diffusivity (AD) values in the anterior 3 callosal segments compared to HCs.
- Participants with PDD had significantly increased AD, mean diffusivity (MD), and radial diffusivity (RD) in the anterior 2 segments compared to participants with PD-NC and most anterior segment compared to participants with PD-MCI.
- The strongest associations for the DTI metrics and cognitive performance occurred in the most anterior and most posterior callosal segments, and also reflected fronto-striatal and posterior cortical type cognitive deficits, respectively.
Bledsoe IO, Stebbins GT, Merkitch D, Goldman JG. White matter abnormalities in the corpus callosum with cognitive impairment in Parkinson disease. [Published online ahead of print December 11, 2019]. Neurology. doi:10.1212/WNL.0000000000006646.