AUTHOR=Brosse Sarah , Tremblay Cécilia , Mérida Inés , Frasnelli Johannes 

TITLE=Specific structural changes in Parkinson’s disease-related olfactory dysfunction compared to others forms of olfactory dysfunction

JOURNAL=Frontiers in Neural Circuits

VOLUME=18

YEAR=2024

URL=https://www.frontiersin.org/journals/neural-circuits/articles/10.3389/fncir.2024.1503841

DOI=10.3389/fncir.2024.1503841

ISSN=1662-5110

ABSTRACT=<sec id="sec1"><title>Context</title><p>Olfactory dysfunction (OD) is a common early symptom of Parkinson’s disease (PD). However, OD is not specific to PD, as approximatively 20% of the general population exhibit different forms of OD. To use olfactory measures for early Parkinson screening, it is crucial to distinguish PD-related OD from Non-Parkinsonian OD (NPOD).</p></sec><sec id="sec2"><title>Objectives and hypothesis</title><p>This study aimed to compare the structural changes associated with PD-related OD (<italic>n</italic> = 15) with NPOD (<italic>n</italic> = 15), focusing on gray matter volumes and white matter fiber integrity in chemosensory regions. We hypothesized that PD-related OD presents specific structural alterations in these regions.</p></sec><sec id="sec3"><title>Methods</title><p>Participants underwent a 3 T MRI scan, which included anatomical T1 and diffusion-weighted imaging. Gray and white matter integrity were assessed using both whole-brain analyses (voxel-based morphometry—VBM and tract-based spatial statistics—TBSS, respectively) and localized approaches, including regions of interest and tractography.</p></sec><sec id="sec4"><title>Results</title><p>PD patients exhibited significantly higher gray matter volume in the left insula using restricted regions-of-interest analyses, while no other significant gray or white matter differences were found between groups.</p></sec><sec id="sec5"><title>Conclusion</title><p>Structural imaging of the gray matter, particularly the insula, but not of white matter, differentiates PD-related OD from NPOD.</p></sec>