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. 2024 Nov 13:18:1503841.
doi: 10.3389/fncir.2024.1503841. eCollection 2024.

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

Sarah Brosse  1 , Cécilia Tremblay  2 , Inés Mérida  3 , Johannes Frasnelli  1   4
Affiliations

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

Sarah Brosse et al. Front Neural Circuits. .

Abstract

Context: 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).

Objectives and hypothesis: This study aimed to compare the structural changes associated with PD-related OD (n = 15) with NPOD (n = 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.

Methods: 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.

Results: 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.

Conclusion: Structural imaging of the gray matter, particularly the insula, but not of white matter, differentiates PD-related OD from NPOD.

Keywords: Parkinson’s disease; gray matter; insula; olfactory dysfunction; trigeminal system; white matter.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Regions of interest in a representative subject, overlaid on the subject’s T1 image. (A) Olfactory regions; (B) trigeminal regions; (C) regions of interaction.
Figure 2
Figure 2
Regions of interest and final tracts in a representative subject, overlaid on the subject’s FA image. (A) Olfactory regions; (B) trigeminal regions; (C) regions of interaction. Blue streamlines in panels (A–C) represent the final tract for each seed-target pair.
See this image and copyright information in PMC

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