Diffusion MRI (dMRI) could be used to understand cognitive impairment in Parkinson’s disease (PD). However, single-tensor (ST)-derived fractional anisotropy (FA) measures are biased due to the presence of crossing-fibers and contamination from cerebrospinal fluid (CSF). CSF contamination can be corrected by fitting a bi-tensor model to estimate free water (FW) contamination. Hence, in this study, we compared FW and FW-corrected ST dMRI-derived measures between PD patients (with and without cognitive impairment) and healthy controls (HC) estimated with multishell dMRI data. Our analysis suggests that FW-corrected dMRI analyses are more powerful in understanding WM disorganization in PD patients with cognitive impairment.