Loss of sense of smell is a well-known non-motor symptom of Parkinson's disease (PD). Here, we present insight into the association between PD advancement and equivalents of smell loss in olfactory-eloquent brain areas, such as the posterior cortex and orbitofrontal cortex. Twelve PD patients in different Hoehn and Yahr stages and 12 healthy normosmic individuals were examined with diffusion tensor imaging. Tract-based spatial statistics were used to analyze microstructural changes in white matter adjacent to the bilateral posterior and orbitofrontal cortex. Axial diffusivity, mean diffusivity, and radial diffusivity were significantly higher in olfactory ROIs in advanced PD patients. The results of this preliminary study indicate that PD advancement is associated with progressive neurodegeneration in olfactory-related brain areas.
Keywords: Parkinson’s disease; diffusion tensor imaging; left posterior piriform cortex; orbitofrontal cortex.