Publication date: Feb 27, 2019
Findings from a small study suggest that increased mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) in the corpus callosum may be associated with cognitive impairment in patients with Parkinson disease (PD). Findings from the study were published in Neurology.
Patients with PD (n=75) and healthy controls (n=24) who had both diffusion tensor imaging (DTI) and structural magnetic resonance imaging (MRI) brain scans in a prospective study of clinical and neuroimaging markers of PD cognitive impairment were included in the study. The researchers characterized patients as having normal cognition (n=23), mild cognitive impairment (n=35), or dementia (PDD) (n=17), according to the Movement Disorder Society criteria.
In addition, DTI scalar values such as fractional anisotropy (FA), MD, AD, and RD were established for the cortical projections of -5 callosal segments on a midsagittal plane, single slice using a topographically derived parcellation method.” The 5 segments included segment 1 (most anterior), prefrontal cortex; segment 2, premotor and supplementary motor cortex; segment 3, motor cortex; segment 4, sensory cortex; and segment 5 (most posterior), parietal, temporal, and occipital cortex. To examine the associations between cognitive domain z-scores and callosal segment DTI values, the researchers performed linear regression analyses.
Compared with healthy controls, patients with PD had increased AD values in the anterior 3 callosal segments (segment 1: P =.033; segment 2: P =.006; segment 3: P =.002). In group pairwise comparison analyses, patients with PDD had increased MD, AD, and RD values vs patients with PD and normal cognition in segment 1 (all P
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